{"slug":"cloudflare-os-kv","title":"Workers KV makes reads fast by making writes slow and consistency optional","body":"Workers KV is a key-value store with one central copy of your data and a cache of that copy in every Cloudflare location that has recently asked for it. Reads from a location that already holds the key are the fastest storage read on the platform. Writes go to the centre and take their time getting everywhere else. Every decision on this page follows from that one asymmetry.\n\nThe short answer to \"should this state live in KV\": if losing sixty seconds of freshness in another continent is survivable, yes. If two requests might write the same key at the same time and the result has to be correct, no.\n\n## Evidence status\n\n**Observed** marks first-party measurements or runtime receipts from the named environment.\n**Derived** marks arithmetic calculated from cited inputs. **Specified** marks vendor or standards\ndocumentation. **Implemented** and **deployed** name code and live-state evidence, respectively.\n**Reproduced** means the stated procedure was rerun. **Externally attested** marks operator reports;\nthose reports show that an experience occurred, not that it is universal.\n\n## Cloudflare's own Workers lead calls the database use a misuse\n\nKenton Varda, who leads the Workers team, answered a developer who had adopted KV as their datastore:\n\n> KV is not a distributed database and is really not intended as a database alternative at all. It's more meant for distributing bits of config globally. Cost aside, writes are way too slow for database-ish use\n\nHe pointed at Durable Object SQLite storage and at Hyperdrive instead. Take the sentence literally: **bits of config**. Flags, routing tables, rendered snapshots, allow-lists, prompt blocks. Not carts, not counters, not sessions that mutate, not anything two writers touch.\n\n[[widget:0]]\n\n## Eventual consistency, in the exact words of the reference\n\nThe Workers Binding API reference states the write behaviour without softening it:\n\n> Due to the eventually consistent nature of KV, concurrent writes to the same key can end up overwriting one another.\n\nand\n\n> Writes are immediately visible to other requests in the same global network location, but can take up to 60 seconds (or the value of the `cacheTtl` parameter of the `get()` or `getWithMetadata()` methods) to be visible in other parts of the world.\n\nThe read reference is equally blunt: `get()` and `getWithMetadata()` \"may return stale values\". The concepts page adds the trap most people miss — **a miss is cached too**:\n\n> Negative lookups indicating that the key does not exist are also cached, so the same delay exists noticing a value is created as when a value is changed.\n\nSo a location that asked for `flag:new_checkout` before you created it will keep answering `null` for up to sixty seconds after the key exists. Nothing retries on your behalf.\n\n### What a reader in another region actually sees after a write\n\n| Moment after the write | Same location as the writer | A location that has never read the key | A location that read the key (or its absence) recently |\n| --- | --- | --- | --- |\n| 0–1 s | New value, usually | New value — nothing cached to serve instead | Old value, or `null` |\n| 1–60 s | New value | New value | Old value, or `null`, until the cached copy times out |\n| After 60 s | New value | New value | New value |\n| With `cacheTtl: 3600` set on the read | New value | New value | Old value for up to an hour |\n\n\"Usually\" is the documentation's word, not a hedge added here: *\"At the Cloudflare global network location at which changes are made, these changes are usually immediately visible. However, this is not guaranteed and therefore it is not advised to rely on this behaviour.\"* There is no read-after-write guarantee anywhere in KV, including at the writing location.\n\n### The safety rule, applied to real states\n\n| State | Safe in KV | Why |\n| --- | --- | --- |\n| Rendered page snapshot | Yes | A stale page is a slightly old page. The next render replaces it. |\n| Feature flag, kill switch | Yes | Rollout is a minute, not a millisecond. One writer, an operator. |\n| Routing table, agent prompt block | Yes | Changes are deliberate and infrequent; a minute of skew is invisible. |\n| Allow-list / deny-list | Yes, with a caveat | Adding is fine. Revocation is not — a revoked entry stays live for the propagation window. Pair with a short `cacheTtl` or a second, authoritative check. |\n| Session state that mutates per request | No | Read-modify-write on the same key. Concurrent writes overwrite each other. |\n| Counter, quota, rate limit | No | Same lost-update problem, every increment. |\n| Shopping cart, order status | No | Two tabs, two writes, one survivor, no error. |\n| A lock over anything contended | No | See the lock section below. |\n| The only copy of any fact | No, except flags | Nothing to rebuild it from when a write is lost. |\n\n## The rates, and the one that is ten times the others\n\nFetched from Cloudflare's KV pricing page today. All rates are per operation on a **per-key** basis; a bulk read of 50 keys is 50 billable reads.\n\n| Operation | Workers Free | Workers Paid (included, then rate) |\n| --- | --- | --- |\n| Read | 100,000 / day | 10 million / month, then $0.50 / million |\n| Write | 1,000 / day | 1 million / month, then $5.00 / million |\n| Delete | 1,000 / day | 1 million / month, then $5.00 / million |\n| List | 1,000 / day | 1 million / month, then $5.00 / million |\n| Stored data | 1 GB | 1 GB, then $0.50 / GB-month |\n\nTwo consequences worth stating flatly. **A write costs the same as ten reads.** And **a miss is billable**: \"All operations incur charges, including fetches for non-existent keys that return a null (Workers API) or HTTP 404 (REST API).\" A cache-aside pattern that checks KV before hitting a database pays for every check, hit or miss. Egress is free.\n\nFree-plan writes are the real cliff. One thousand writes a day is roughly one write every ninety seconds, sustained. Any per-request write pattern exhausts it before lunch.\n\n[[widget:1]]\n\n## kondro's 2021 arithmetic still prices out correctly in 2026\n\nFive years ago, on a Hacker News thread about R2 pricing, a commenter laid out the KV objection:\n\n> Workers KV is also eventually-consistent with no guarantee of read-after-write, which is a pretty big limitation compared to alternatives (S3 even has immediately-consistent list operations now after write).\n\nThe same comment put KV at $5 per million writes and $0.50 per million reads, called the reads pricier than S3's, and set that against Durable Object storage at $1 per million 4 KB writes with the Durable Object runtime cost stacked on top. Checked against today's published pages:\n\n| kondro's 2021 figure | Published rate, July 2026 | Verdict |\n| --- | --- | --- |\n| KV writes $5 / million | $5.00 / million | Unchanged |\n| KV reads $0.50 / million | $0.50 / million | Unchanged |\n| KV reads pricier per read than S3 | S3 Standard GET is \"$0.0004 per 1,000 requests\" = $0.40 / million | Still true. KV reads cost 25% more per operation. |\n| Durable Object storage $1 / million writes | SQLite-backed Durable Object storage: $1.00 / million rows written, first 50 million / month included | Same rate, and the free allowance is now fifty times KV's |\n| Durable Object runtime cost on top | $0.15 / million requests plus $12.50 / million GB-s of duration | Still stacked, and still the reason KV wins on pure read serving |\n\nThe one number that moved in KV's favour is nothing to do with KV: Durable Object storage now includes 50 million row writes a month against KV's 1 million. For a write-heavy key, a Durable Object is now cheaper *and* correct.\n\nR2 is the other comparison people make and get wrong in KV's favour. R2 Class B operations — the reads — are **$0.36 per million**, cheaper than KV's $0.50, with 10 million a month free and 10 GB of storage free against KV's 1 GB. R2 loses on latency, not on price.\n\n## Bounding writes by putting the edge cache in front of KV\n\nThe write rate, not the read rate, is what turns a KV bill into a surprise. An operator running a share-link backend described the defence, in a thread about a Durable Object alarm loop that had burned $34,000 in eight days:\n\n> The key property is that caches.default with Cache-Control: max-age=3600 becomes a natural throttle — at most 24 cache misses per day per key, so KV writes are bounded by (keys × 24) regardless of traffic.\n\nThe mechanism, step by step:\n\n1. The Worker checks `caches.default` first. A hit returns without touching KV at all — no read charge, no write charge.\n2. Only a miss reaches KV. Only a miss can trigger the refresh write.\n3. `Cache-Control: max-age=3600` means a given key can only miss once an hour per cache location.\n4. Therefore the *write* count per key is bounded by the number of cache expiries, not by the number of requests. Traffic can multiply by a thousand and the write bill does not move.\n\n**What it costs you:** freshness. A value written now is invisible behind that cache for up to an hour, on top of KV's own propagation window. You are choosing a bounded bill over a bounded staleness, and you cannot have both.\n\nThis codebase runs the same pattern with a shorter window. `functions/_middleware.js` sets `LASTGOOD_REFRESH_MS = 120000` and `refreshLastGood()` returns early when the stored snapshot is younger than that, so any one path writes its snapshot at most once per two minutes no matter how many misses arrive. The edge cache in front carries `public, max-age=120, s-maxage=600, stale-while-revalidate=86400` for article pages. The measured result is in the last section: 12,231 writes a day across 6,568 snapshot keys, against a theoretical ceiling of 6,568 × 720 = 4.7 million.\n\n## The per-key boundaries, and the error you get at each one\n\n| Limit | Value | What happens at the boundary |\n| --- | --- | --- |\n| Key size | 512 bytes | The operation is rejected. Long composite keys are the usual cause. |\n| Value size | 25 MiB | Write rejected. Anything approaching this belongs in [R2](/a/cloudflare-os-r2). |\n| Metadata size | 1024 bytes, serialized JSON | Write rejected. Metadata rides along with `list()` results, which is why it is worth keeping small deliberately. |\n| Writes to the same key | 1 per second, free and paid alike | Excess writes fail. This is a hard rate limit, not a billing threshold. |\n| Operations per Worker invocation | 1,000 | A bulk request counts as one. |\n| `expirationTtl` minimum | 60 seconds | Shorter values are rejected. A sub-minute lease is not expressible. |\n| `cacheTtl` minimum | 30 seconds | Below this the parameter is refused. |\n| Namespaces per account | 1,000 | — |\n\nThe key-size limit is the one that bites in production because it fails late and looks like something else. A pull request against Cloudflare's own `vinext` framework describes it exactly:\n\n> When the assembled key exceeds Cloudflare KV's 512-byte key limit, `handler.get` throws a 414 **before** the wrapped function runs — so control-flow signals like `notFound()`/`redirect()` never fire, and the user sees a generic 200 error boundary instead of a 404.\n\nTheir fix is the one to copy: budget for your prefix (they used 480 bytes to leave room for `<appPrefix>:cache:`), keep short keys verbatim so they stay debuggable, and hash only the overflowing part.\n\n## An eventually-consistent store cannot hold a lock, and this application's locks are only safe because nobody is racing\n\nThe honest answer first. A lock needs compare-and-set: test that nobody holds it and take it, atomically, with no window between the test and the take. KV has no such primitive. `get()` then `put()` is two operations with a gap, and the reference already told you what happens in that gap — concurrent writes to the same key overwrite one another, last write wins, no error returned to the loser.\n\nThree KV locks run in this application, all with the same shape:\n\n- **`locks:deploy:loop-safe-miscsubjects`** — `functions/_lib/fn_runners.js`, the `deployLease` runner. Reads the key, returns `ERR:deploy_lease:held:` if a live lease exists, otherwise writes a lease with a random `nonce` and `expirationTtl: 1800`. Release requires presenting the matching nonce, so a stale holder cannot free somebody else's lease. `scripts/ship.mjs` takes this lease before every deploy.\n- **`selftest:lock`** — `functions/api/selftest.js`. Same read-then-write, `expirationTtl: 1800`, with a 1,500,000 ms staleness window on the stored timestamp so an abandoned run does not block the next one forever.\n- **`fclaim:*`** — advisory file claims so two coding agents do not edit the same file, default lease 90 minutes.\n\nEach of these is a genuine race. Two `acquire` calls landing inside the same second both read no lease, both write, and the second write wins silently. What makes the pattern survivable here, and the condition must be said out loud:\n\n**These locks are safe only because contention is near zero.** A deploy happens a few times a day, initiated by a human or one agent. A self-test run is a scheduled singleton. Two agents claiming the same file inside the same second is a coincidence, not a workload. Change any of those assumptions — a deploy fired by webhook on every push, a self-test on a one-minute cron — and the lock stops working, quietly, with no error to tell you.\n\nThe codebase already contains the correction for the case where contention is real. `functions/_lib/idem_claim.js` guards invoke idempotency, where duplicate parallel calls are the normal case rather than a coincidence, and its opening comment records why it is not in KV:\n\n> KV get→fire→put races: parallel identical calls all miss, all fire.\n\nIt uses `INSERT OR IGNORE` on a D1 table instead, where the primary key does the atomic test-and-set that KV cannot. That is the rule generalised: **if two writers can plausibly arrive together, the lock goes in D1 or a Durable Object, not KV.** Cloudflare's own guidance says the same thing — \"KV is not ideal for applications where you need support for atomic operations or where values must be read and written in a single transaction.\"\n\n[[widget:2]]\n\n## The topology teams settle on: authority elsewhere, KV as the replicated read copy\n\nAsked how they ran a global read path, one operator described the shape that keeps recurring:\n\n> Cloudflare Workers KV has the simplest model, with a central-db that transparently and eventually only replicates read-only, hot-data specific to a DC but writes continue to incur heavy penalty\n\nTheir production system used DynamoDB in a single region as the source of truth, DynamoDB Streams pushing changes into Workers KV, and reads served from KV at the edge. Writes never touched KV directly. The reasons they gave were operations per second, cost and latency — and avoiding lock-in.\n\nThe generalised topology, and it is the one to copy:\n\n1. **Authority** — a store with transactions: D1, a Durable Object, Postgres behind Hyperdrive, DynamoDB. All writes land here and here only.\n2. **Propagation** — a change feed, a queue, or the write path itself pushes the new value into KV as a side effect. One writer per key, which is exactly what the reference recommends: *\"It is a common pattern to write data from a single process with Wrangler, Durable Objects, or the API. This avoids competing concurrent writes because of the single stream.\"*\n3. **Read** — every edge read hits KV. It is allowed to be a minute stale because the authority, not KV, is what anybody reconciles against.\n\nTwo field reports bracket the tradeoff. On the positive side, the author of an edge feature-flag system:\n\n> I mostly use KV for storing flags specific to each project (which gets replicated automatically). Everything else goes to D1 (replication isn't needed here).\n\nOn the negative side, the bind that pushes people into KV whether it fits or not:\n\n> You can use KV, with its trade-off of eventual consistency, or use something like FaunaDB or Firebase, but that means that the request has to wait for the request to the backing service.\n\nBoth are true at once. KV is the only storage on the platform that is already next to the Worker; everything else is a network hop. That is the whole reason people put things in it that do not belong there.\n\nAnd a measured case of KV in the cache role paying off: an operator repeatedly tripping D1's 5 million daily row-read limit put a KV layer in front and reported back a week later — *\"I implemented KV-layered caching\"* — with reads down more than 80% and back under the limit. That is KV doing the job it is for. See [D1 in this stack](/a/cloudflare-os-d1) for the read-accounting model that makes those limits bite.\n\n## Where each kind of state belongs\n\n| If the state is… | KV | [D1](/a/cloudflare-os-d1) | [R2](/a/cloudflare-os-r2) | Durable Object storage | Cache API |\n| --- | --- | --- | --- | --- | --- |\n| Read from everywhere, written rarely, seconds of staleness fine | **Use this** | Slower reads, and rows read are metered | Higher latency, cheaper per read | Single-location reads | Not durable |\n| Relational, queried by more than a key | No | **Use this** | No | Only if scoped to one object | No |\n| Large bytes: images, video, archives | No — 25 MiB ceiling | No | **Use this** — free egress, $0.015/GB-month | No | No |\n| Coordination, counters, anything atomic | **Never** | Workable via `INSERT OR IGNORE` | No | **Use this** — single-threaded, transactional | No |\n| Per-request ephemeral output, regenerable | Wasteful — pays a write | No | No | No | **Use this** — free, per-location, non-durable |\n| The source of truth for money or identity | **Never** | Yes | Yes for blobs | Yes | Never |\n| Sixty-second global propagation is unacceptable | No | Yes | Yes | Yes | Yes, per location |\n\nThe Cache API row deserves its own sentence because it is the cheapest option on the table and the most often skipped: `caches.default` costs nothing per operation, is not durable, and is scoped to one Cloudflare location. Put it in front of KV, as above, and it is what bounds the write bill.\n\n## Symptom, cause, fix\n\n| Symptom | Cause | Fix |\n| --- | --- | --- |\n| A value written a second ago reads as the old one, but only for some users | The reading location has a cached copy, or a cached negative lookup, from before the write | Wait out the 60-second window, or lower `cacheTtl`, or read from the authority instead of KV on the path that needs freshness |\n| A key you just created reads as `null` in one region | Negative lookups are cached the same as values | Do not pre-read a key before writing it. If a probe is unavoidable, treat `null` as unknown, not absent |\n| `handler.get` throws a **414**, and the framework's `notFound()` never runs | Assembled key exceeded 512 bytes | Budget for the prefix, keep short keys verbatim, hash the overflow |\n| Writes silently stop landing on one key | 1 write per second per key, free and paid | Spread across discrete keys, or move that key to a Durable Object |\n| The bill is dominated by an operation nobody thought about | Writes are $5.00 / million against reads at $0.50 | Put the Cache API in front so writes are bounded by cache expiries, not by traffic |\n| Two processes both believe they hold the lock | `get()` then `put()` is not atomic; last write wins with no error | Move the lock to D1 `INSERT OR IGNORE` or a Durable Object |\n| Free plan stops accepting writes mid-afternoon | 1,000 writes/day, reset 00:00 UTC | Batch, throttle behind a cache, or move to the paid plan |\n| `expirationTtl: 30` rejected | Minimum is 60 seconds | Store the intended expiry inside the value and check it on read |\n\n## Measured on this account today\n\nFive measurements taken against the live namespace bound as `KV` in `wrangler.toml`. Account id and namespace ids are redacted below; substitute your own. The consistency probe wrote two obviously-named temporary keys, `tmp_consistency_probe_20260725` and `tmp_consistency_probe_b_20260725`, and both were deleted afterwards and verified gone (HTTP 404).\n\n**1. Namespaces on the account — 6.**\n\n```\nnpx wrangler kv namespace list\n```\n\n**2. Keys in the production namespace — 6,773, of which 6,568 are page snapshots.**\n\n```\nnpx wrangler kv key list --namespace-id <NAMESPACE_ID> --remote > keys.json\npython3 -c \"import json;d=json.load(open('keys.json'));print(len(d))\"\n```\n\nPrefix breakdown: `lastgood:` 6,568, `sync:` 35, `trail:` 33, `share_use:` 25, `mcp_oauth:` 18, `idem:` 6, then singletons. The longest key name measured **110 bytes** against the 512-byte limit.\n\n**3. Stored bytes — 164.70 MB across the 1,041 snapshot keys that carry size metadata.** `refreshLastGood()` writes `{ts, bytes, ct}` as KV metadata, so `list()` returns the size of every value it wrote without reading any of them.\n\n```\npython3 -c \"import json;d=json.load(open('keys.json'));b=[k['metadata']['bytes'] for k in d if k.get('metadata',{}).get('bytes')];print(len(b),sum(b),max(b))\"\n```\n\nMedian value 155,154 bytes, largest 2,140,072 bytes — 8% of the 25 MiB ceiling. Extrapolating that mean across all 6,568 snapshot keys puts the namespace at roughly **1.01 GB**, which is the 1 GB included allowance almost exactly; the overage at $0.50/GB-month is about half a cent. Treat the extrapolation as an estimate: the 5,527 older keys without metadata were not measured.\n\n**4. Seven days of real operations — 899,100 reads, 85,620 writes, 740 deletes, 160 lists.** From Cloudflare's GraphQL analytics API, 2026-07-19 to 2026-07-26.\n\n```\nPOST https://api.cloudflare.com/client/v4/graphql\n{\"query\":\"query { viewer { accounts(filter: {accountTag: \\\"<ACCOUNT_ID>\\\"}) {\n  kvOperationsAdaptiveGroups(limit: 100, filter: {\n    datetime_geq: \\\"2026-07-19T00:00:00Z\\\", datetime_leq: \\\"2026-07-26T00:00:00Z\\\",\n    namespaceId: \\\"<NAMESPACE_ID>\\\"}) { sum { requests } dimensions { actionType } } } } }\"}\n```\n\nThe arithmetic that matters:\n\n| Operation | 7-day count | Rate | Gross at list rates |\n| --- | --- | --- | --- |\n| Read | 899,100 | $0.50 / million | $0.4496 |\n| Write | 85,620 | $5.00 / million | $0.4281 |\n| Delete | 740 | $5.00 / million | $0.0037 |\n| List | 160 | $5.00 / million | $0.0008 |\n| **Total** | **985,620** | — | **$0.8822** |\n\nWrites are **8.7% of the operations and 48.5% of the gross cost**. Extrapolated to a month: 3.85 million reads against the 10 million included, and 366,943 writes against the 1 million included — so the actual invoice line is **$0.00**. The write allowance is the binding constraint, with 2.7× headroom: 12,231 writes a day today, 33,333 a day before the meter starts.\n\n[[widget:3]]\n\n**5. Write, then read, and time the gap — visible in 0.21 s and 0.30 s across two trials.**\n\n```\n# seed the negative lookup at the reading location\nfor i in $(seq 1 6); do curl -s -o /dev/null -w \"%{http_code} \" \\\n  \"https://miscsubjects.com/api/kv?key=tmp_consistency_probe_b_20260725\" \\\n  -H \"x-terminal-key: $TERMINAL_KEY\"; sleep 2; done       # 404 404 404 404 404 404\n\nnpx wrangler kv key put tmp_consistency_probe_b_20260725 probe-b \\\n  --namespace-id <NAMESPACE_ID> --remote                   # real 1.14s\n\n# poll every 0.5s until it appears\nfor i in $(seq 1 200); do code=$(curl -s -o /tmp/pb.txt -w \"%{http_code}\" \\\n  \"https://miscsubjects.com/api/kv?key=tmp_consistency_probe_b_20260725\" \\\n  -H \"x-terminal-key: $TERMINAL_KEY\"); \\\n  [ \"$code\" = \"200\" ] && break; sleep 0.5; done            # t+0.21s VISIBLE probe-b\n```\n\nBoth trials converged in well under a second, including the trial that deliberately seeded six cached negative lookups first. **This does not demonstrate read-after-write consistency and must not be read as one.** It measures one reading location, close to the writer, twice. The documented window is a worst case, and the reference says explicitly that even same-location visibility \"is not guaranteed\". A system that happens to converge fast today is not a system you can design against.\n\nTen repeat reads of the same key through the deployed Worker, end to end over HTTPS from a laptop: minimum 136 ms, median 202 ms, maximum 260 ms. Almost all of that is network round trip, not KV — Cloudflare's own instrumentation puts the 90th percentile of KV Worker invocations \"in less than 12 ms\", and reports that the hottest 0.03% of keys, which serve over 40% of global KV requests, \"resolve in under a millisecond\".\n\nAn independent benchmark run from Cloudflare's Washington DC location (150 samples per metric, KV through the binding against Upstash Redis over HTTPS, same Worker, same request) put KV's hot read at **2.6 ms p50** — twice as fast as the competitor — and KV's single write at **171.8 ms p50**, twenty-eight times slower. That single pair of numbers is the whole argument of this page in measured form: KV's reads are the best on the platform and its writes are the worst.\n\nFor where KV sits among the other bindings in this stack, see [the Cloudflare stack index](/a/cloudflare-os), [Workers as the runtime](/a/cloudflare-os-workers) and [D1 as the relational store](/a/cloudflare-os-d1).\n\n## The next read-only inventory still shows snapshots dominating the namespace\n\nWrangler 4.103.0 listed the production namespace at `2026-07-26T05:45:59.424Z`. Listing reads namespace metadata; it did not write, delete or fetch any value.\n\n| Fresh check | Result |\n| --- | ---: |\n| Namespaces on the account | 6 |\n| Keys in the production namespace | 6,767 |\n| `lastgood:` snapshot keys | 6,568 |\n| Longest key name | 110 bytes of the 512-byte limit |\n| Keys carrying byte-count metadata | 1,046 |\n| Bytes recorded by that metadata | 175,859,336 |\n| Largest recorded value | 2,140,072 bytes |\n\nLargest prefix groups: `lastgood:` 6,568 · `(singleton)` 54 · `sync:` 35 · `trail:` 33 · `share_use:` 25 · `mcp_oauth:` 18. The inventory reproduces the architectural claim directly: 97% of all keys are regenerable `lastgood:` page snapshots, not transactional state.\n\nRun the same inventory without exposing the namespace id in a transcript:\n\n```bash\nnpx wrangler kv namespace list\nnpx wrangler kv key list --namespace-id <NAMESPACE_ID> --remote > keys.json\npython3 -c \"import json; d=json.load(open('keys.json')); print(len(d), max(len(k['name'].encode()) for k in d))\"\n```\n\nThe first number is the key count. The second is the longest key name in bytes.","hero":"https://miscsubjects.com/img/up/cloudflare-os-kv-hero-card.png","images":[],"style":{},"tags":["cloudflare","architecture","kv","cloudflare-os","workers-kv","cache","eventual-consistency","durable-objects","pricing"],"model":"Opus 5 (Claude Code)","ledger":{"href":"/api/articles/cloudflare-os-kv/ledger","live":true},"embeds":[],"widgets":[{"type":"note","title":"KV is a replicated read copy","text":"Keep authority in D1, a Durable Object or another transactional database. Push slow-changing snapshots and configuration into KV for global reads."},{"type":"stat","value":"10×","label":"KV write price versus read price: $5.00 and $0.50 per million"},{"type":"note","title":"A KV lock is advisory only","text":"get() then put() is not atomic. If two writers can plausibly arrive together, use D1 INSERT OR IGNORE or a Durable Object."},{"type":"stat","value":"8.7% → 48.5%","label":"writes as a share of measured operations versus gross list-rate cost"},{"type":"stat","value":"60 seconds","label":"documented global propagation window for stale values and cached misses"},{"type":"stat","value":"6,767","label":"keys in the fresh read-only production inventory"},{"type":"quote","text":"KV is not a distributed database and is really not intended as a database alternative at all.","cite":"Kenton Varda, Cloudflare Workers lead, Hacker News, 2026-06-25"},{"type":"stat","value":"110 / 512 bytes","label":"longest live key name versus the hard per-key limit"}],"home":true,"claims":[{"id":"c1","text":"Workers KV is a globally cached key-value read layer with eventual propagation, not a transactional distributed database.","section":"Cloudflare's own Workers lead calls the database use a misuse","tier":"system","source_ids":["p1","s1"],"why_material":"This is the governing architecture constraint.","evidence_status":"specified + externally attested"},{"id":"c2","text":"A recently read value or missing key can remain stale in another location for up to 60 seconds or the configured cacheTtl.","section":"Eventual consistency, in the exact words of the reference","tier":"fact","source_ids":["s1","s2"],"why_material":"Consumers must decide whether that freshness loss is survivable.","evidence_status":"specified"},{"id":"c3","text":"Concurrent writes to one KV key can overwrite one another without an atomic compare-and-set.","section":"Eventual consistency, in the exact words of the reference","tier":"fact","source_ids":["r4","s3"],"why_material":"It rules out counters, locks and contended read-modify-write state.","evidence_status":"observed + specified"},{"id":"c4","text":"KV writes cost $5 per million after the allowance while reads cost $0.50 per million.","section":"The rates, and the one that is ten times the others","tier":"fact","source_ids":["p2","s5"],"why_material":"Writes cost ten times reads and dominate write-heavy workloads.","evidence_status":"specified + externally attested"},{"id":"c5","text":"A missing-key read is billable even though it returns null or 404.","section":"The rates, and the one that is ten times the others","tier":"fact","source_ids":["s5"],"why_material":"Cache-aside misses still consume the read meter.","evidence_status":"specified"},{"id":"c6","text":"The 2021 operator price comparison still matches the July 2026 KV read and write rates.","section":"kondro's 2021 arithmetic still prices out correctly in 2026","tier":"calculation","source_ids":["p2","s5"],"why_material":"The historical warning remains economically current.","evidence_status":"specified + externally attested"},{"id":"c7","text":"Putting caches.default before KV bounds refresh writes by cache expiry rather than request traffic.","section":"Bounding writes by putting the edge cache in front of KV","tier":"system","source_ids":["p5","s6"],"why_material":"It converts an unbounded traffic-driven bill into a deliberate freshness tradeoff.","evidence_status":"specified + externally attested"},{"id":"c8","text":"KV limits keys to 512 bytes, values to 25 MiB, metadata to 1024 bytes and same-key writes to one per second.","section":"The per-key boundaries, and the error you get at each one","tier":"fact","source_ids":["s4"],"why_material":"These are schema and traffic boundaries, not tuning suggestions.","evidence_status":"specified"},{"id":"c9","text":"A merged vinext repair preserves short cache keys and hashes the overflow after reserving prefix space to avoid KV 414 failures.","section":"The per-key boundaries, and the error you get at each one","tier":"repository","source_ids":["s9"],"why_material":"It is a concrete repair for a production key-shape failure.","evidence_status":"implemented"},{"id":"c10","text":"KV get then put cannot implement a correct contended lock; D1 INSERT OR IGNORE or a Durable Object can.","section":"An eventually-consistent store cannot hold a lock, and this application's locks are only safe because nobody is racing","tier":"system","source_ids":["r4","s3"],"why_material":"Silent double ownership is worse than an explicit lock failure.","evidence_status":"observed + specified"},{"id":"c11","text":"The durable topology is transactional authority first, one propagation stream second and KV as the replicated read copy.","section":"The topology teams settle on: authority elsewhere, KV as the replicated read copy","tier":"system","source_ids":["p3","p6","s7"],"why_material":"It gives KV one writer per key and keeps reconciliation against an authoritative store.","evidence_status":"specified + externally attested"},{"id":"c12","text":"An operator uses KV for replicated project flags while keeping everything else in D1.","section":"The topology teams settle on: authority elsewhere, KV as the replicated read copy","tier":"anecdotal","source_ids":["p6"],"why_material":"It is a positive report aligned with KV's consistency model.","evidence_status":"externally attested"},{"id":"c13","text":"Another operator describes the latency tradeoff between eventual KV reads and waiting for an external authoritative database.","section":"The topology teams settle on: authority elsewhere, KV as the replicated read copy","tier":"anecdotal","source_ids":["p4"],"why_material":"It explains why teams misuse KV despite understanding the consistency cost.","evidence_status":"externally attested"},{"id":"c14","text":"A cache-fronted share-link design bounds each key to at most 24 cache misses per day with a one-hour max-age.","section":"Bounding writes by putting the edge cache in front of KV","tier":"anecdotal","source_ids":["p5"],"why_material":"It is a positive operator pattern with explicit economics and staleness.","evidence_status":"externally attested"},{"id":"c15","text":"The seven-day account measurement recorded 899,100 reads, 85,620 writes, 740 deletes and 160 lists.","section":"Measured on this account today","tier":"measurement","source_ids":["r2"],"why_material":"It supplies the actual operation mix behind the cost calculation.","evidence_status":"observed"},{"id":"c16","text":"In the measured week, writes were 8.7% of operations but 48.5% of gross list-rate cost.","section":"Measured on this account today","tier":"calculation","source_ids":["r2","s5"],"why_material":"It shows why write control matters before total traffic looks large.","evidence_status":"observed + specified"},{"id":"c17","text":"Two same-area visibility trials converged in 0.21 and 0.30 seconds, but neither establishes read-after-write consistency.","section":"Measured on this account today","tier":"measurement","source_ids":["r3","s1"],"why_material":"Observed speed is separated from the documented guarantee.","evidence_status":"observed + specified"},{"id":"c18","text":"The independent IAD benchmark used 150 samples per metric and measured KV hot reads at 2.6 ms p50 and writes at 171.8 ms p50.","section":"Measured on this account today","tier":"independent","source_ids":["s11"],"why_material":"A disclosed competitor harness still captures the read-fast/write-slow asymmetry.","evidence_status":"observed"},{"id":"c19","text":"Cloudflare reports that its hottest 0.03% of keys serve over 40% of global KV requests and resolve in under one millisecond.","section":"Measured on this account today","tier":"publisher_claim","source_ids":["s8"],"why_material":"It explains why hot edge reads can be exceptionally fast.","evidence_status":"specified"},{"id":"c20","text":"The fresh namespace list found 6,767 keys, including 6,568 regenerable lastgood snapshots.","section":"The next read-only inventory still shows snapshots dominating the namespace","tier":"measurement","source_ids":["r1"],"why_material":"The live key mix matches the recommended read-copy role.","evidence_status":"observed"},{"id":"c21","text":"The longest live key name is 110 bytes, below the 512-byte hard limit.","section":"The next read-only inventory still shows snapshots dominating the namespace","tier":"measurement","source_ids":["r1","s4"],"why_material":"It verifies current headroom against a known failure boundary.","evidence_status":"observed + specified"},{"id":"c22","text":"Fresh list metadata covers 1,046 values totaling 175,859,336 recorded bytes; the largest is 2,140,072 bytes.","section":"The next read-only inventory still shows snapshots dominating the namespace","tier":"measurement","source_ids":["r5"],"why_material":"It measures snapshot storage without fetching bodies.","evidence_status":"observed"},{"id":"c23","text":"Cloudflare's own documentation repository records explicit clarifications to the KV consistency contract.","section":"Eventual consistency, in the exact words of the reference","tier":"repository","source_ids":["s10"],"why_material":"The public source history makes the contract auditable.","evidence_status":"implemented"}],"sources":[{"id":"s1","type":"specification","url":"https://developers.cloudflare.com/kv/concepts/how-kv-works/","title":"How Workers KV works","quote":"Negative lookups indicating that the key does not exist are also cached, so the same delay exists noticing a value is created as when a value is changed.","summary":"Normative consistency model: central storage, regional caches, stale values and cached misses.","publisher":"Cloudflare","claim_ids":["c1","c17","c2"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"genesis","hash":"25a663bdc376c779923fc6158fd7c65c5a0330f9dfe455a4f62dd4295c4cc55f"},{"id":"s2","type":"specification","url":"https://developers.cloudflare.com/kv/api/read-key-value-pairs/","title":"Read key-value pairs","quote":"get() and getWithMetadata() methods may return stale values.","summary":"Workers Binding API for reads, metadata and cacheTtl, including the stale-read warning.","publisher":"Cloudflare","claim_ids":["c2"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"25a663bdc376c779923fc6158fd7c65c5a0330f9dfe455a4f62dd4295c4cc55f","hash":"bb2f0147961457bb720e1909a6859cfa58ca16927ceb54b0cc15b3e49382388a"},{"id":"s3","type":"specification","url":"https://developers.cloudflare.com/kv/api/write-key-value-pairs/","title":"Write key-value pairs","quote":"Due to the eventually consistent nature of KV, concurrent writes to the same key can end up overwriting one another.","summary":"Workers Binding API for put, metadata and expiry, including the concurrent-write warning.","publisher":"Cloudflare","claim_ids":["c10","c3"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"bb2f0147961457bb720e1909a6859cfa58ca16927ceb54b0cc15b3e49382388a","hash":"c43a365f1fdff1dc9df212c2d6be72787619ff5aa5787a0f8be900f384ea5a17"},{"id":"s4","type":"publisher_documentation","url":"https://developers.cloudflare.com/kv/platform/limits/","title":"Workers KV limits","quote":"Writes to same key","summary":"Hard per-key, per-value, metadata, namespace and invocation limits.","publisher":"Cloudflare","claim_ids":["c21","c8"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"c43a365f1fdff1dc9df212c2d6be72787619ff5aa5787a0f8be900f384ea5a17","hash":"124486035d659fc7ad02c66f3a714dc20efe2c93f19c512758c79b36b42589b8"},{"id":"s5","type":"publisher_documentation","url":"https://developers.cloudflare.com/kv/platform/pricing/","title":"Workers KV pricing","quote":"All operations incur charges, including fetches for non-existent keys that return a null (Workers API) or HTTP 404 (REST 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KV.","publisher":"Cloudflare","claim_ids":["c7"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"cf304f6de8d11281754680e5926e7c0f099a6bc15e038afb207260c65092c523","hash":"d28a8dcfd8fa323d1b306709e38970dcbbc775d051e97c1ca78874dade47c655"},{"id":"s7","type":"publisher_documentation","url":"https://developers.cloudflare.com/workers/platform/storage-options/","title":"Workers storage options","quote":"This guide describes the storage & database products available as part of Cloudflare Workers, including recommended use-cases and best practices.","summary":"Official comparison surface for KV, D1, Durable Objects, R2 and external databases.","publisher":"Cloudflare","claim_ids":["c11"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"d28a8dcfd8fa323d1b306709e38970dcbbc775d051e97c1ca78874dade47c655","hash":"747ec212aaf55769a366b77bd1d2bae1e4cd56bb81389a7c1343072e88133b44"},{"id":"s8","type":"publisher_documentation","url":"https://blog.cloudflare.com/faster-workers-kv/","title":"Cloudflare's Workers KV latency measurements","quote":"KV reads for these keys, which represent over 40% of Workers KV requests globally, resolve in under a millisecond.","summary":"Vendor measurement of the tiered cache architecture and hot-key latency distribution.","publisher":"Cloudflare","date":"2024-09-26","claim_ids":["c19"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"747ec212aaf55769a366b77bd1d2bae1e4cd56bb81389a7c1343072e88133b44","hash":"e2619fd67cada3f4e1be8bbe3a79151e07934b584ac919808c1d63a18f95f30b"},{"id":"s9","type":"repository","url":"https://github.com/cloudflare/vinext/pull/2606","title":"vinext fix for KV's 512-byte cache-key limit","quote":"When the assembled key exceeds Cloudflare KV's 512-byte key limit, `handler.get` throws a 414 **before** the wrapped function runs","summary":"Merged code repair: retain short keys and hash only overflow after reserving prefix space.","author":"blitss","publisher":"GitHub","date":"2026-07-13","claim_ids":["c9"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"e2619fd67cada3f4e1be8bbe3a79151e07934b584ac919808c1d63a18f95f30b","hash":"56f18f5cf6a2ed0ccab15b64cee7150cbbd8edbcda19de4bab11e372d20bb4d5"},{"id":"s10","type":"repository","url":"https://github.com/cloudflare/cloudflare-docs/pull/2678","title":"Cloudflare documentation clarification for KV consistency","quote":"Add KV clarifications","summary":"Public documentation change where stale reads, concurrent overwrites and cache behavior are visible in the source history.","publisher":"GitHub","date":"2021-11-11","claim_ids":["c23"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"56f18f5cf6a2ed0ccab15b64cee7150cbbd8edbcda19de4bab11e372d20bb4d5","hash":"b41d1481d70c92ba75a71d83dcd1ab40fcf19e66c6cdd388d438972d05a35eb0"},{"id":"s11","type":"independent_measurement","url":"https://upstash.com/blog/upstash-redis-vs-cloudflare-kv","title":"Upstash Redis versus Cloudflare KV benchmark","quote":"I deployed a Cloudflare Worker that calls KV through the binding and Upstash through the official @upstash/redis/cloudflare client (HTTPS REST), then ran four scenarios: 5 runs × 30 samples = 150 samples per metric, all served from Cloudflare's Washington DC data center (IAD).","summary":"Competitor-authored but reproducible harness: 150 samples per metric from one Worker and one location, with KV binding and Upstash HTTPS held side by side.","author":"Josh","publisher":"Upstash","date":"2026-05-27","claim_ids":["c18"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"b41d1481d70c92ba75a71d83dcd1ab40fcf19e66c6cdd388d438972d05a35eb0","hash":"450ab2c6b14a727ea1637c26dd3b64ef51b25a4fbd8d80f0b94e3434b9707ae6"},{"id":"p1","type":"hn","url":"https://news.ycombinator.com/item?id=48672342","title":"OAuth for all","quote":"KV is not a distributed database and is really not intended as a database alternative at all. It's more meant for distributing bits of config globally. Cost aside, writes are way too slow for database-ish use","summary":"The Workers tech lead telling a user who had adopted KV as a datastore that this is a misuse: writes are too slow and eventual consistency is wrong for frequently-changing state, and to use Durable Objects SQLite or Hyperdrive instead. Negative on the common KV-as-database pattern.","author":"kentonv","publisher":"Hacker News","date":"2026-06-25","claim_ids":["c1"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"450ab2c6b14a727ea1637c26dd3b64ef51b25a4fbd8d80f0b94e3434b9707ae6","hash":"c4bf1f054fc164522d3a721b6cf6d6b6af2482b5c49b6d6858fa3040495c48ec"},{"id":"p2","type":"hn","url":"https://news.ycombinator.com/item?id=28703233","title":"A bit of math around Cloudflare's R2 pricing model","quote":"Workers KV is also eventually-consistent with no guarantee of read-after-write, which is a pretty big limitation compared to alternatives (S3 even has immediately-consistent list operations now after write).","summary":"Cost and consistency breakdown: KV at $5/million writes and $0.50/million reads (pricier per read than S3), plus no read-after-write guarantee. Contrasts with Durable Objects storage at $1/million 4KB writes but with the DO runtime cost stacked on top. Negative.","author":"kondro","publisher":"Hacker News","date":"2021-09-30","claim_ids":["c4","c6"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"c4bf1f054fc164522d3a721b6cf6d6b6af2482b5c49b6d6858fa3040495c48ec","hash":"b0ae1f09af39d9b55b1a6b47f028c4753de7f3b91b508e0e8861a72c773ed75f"},{"id":"p3","type":"hn","url":"https://news.ycombinator.com/item?id=22644115","title":"Launch HN: Fly.io (YC W20) – Deploy app servers close to your users","quote":"Cloudflare Workers KV has the simplest model, with a central-db that transparently and eventually only replicates read-only, hot-data specific to a DC but writes continue to incur heavy penalty","summary":"Describes their actual production topology: DynamoDB as single-region source of truth, DynamoDB Streams pushing into Workers KV, reads served from KV at the edge. They deliberately keep writes off KV because of ops-per-second, cost and latency penalties, and to avoid lock-in. Mixed, leaning negative on KV writes.","author":"ignoramous","publisher":"Hacker News","date":"2020-03-21","claim_ids":["c11"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"b0ae1f09af39d9b55b1a6b47f028c4753de7f3b91b508e0e8861a72c773ed75f","hash":"7f95c19d457b58f3149a9083cfe1f4856c471b0d710f424cbc573bec36a703fa"},{"id":"p4","type":"hn","url":"https://news.ycombinator.com/item?id=28581040","title":"Reality Check for Cloudflare Wasm Workers and Rust","quote":"You can use KV, with its trade-off of eventual consistency, or use something like FaunaDB or Firebase, but that means that the request has to wait for the request to the backing service.","summary":"Frames the practical bind: Workers have no durable disk and no region control, so you either accept KV's eventual consistency or pay a round trip to an external database. Also finds Workers Unbound pricing opaque. Negative.","author":"DenseComet","publisher":"Hacker News","date":"2021-09-19","claim_ids":["c13"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"7f95c19d457b58f3149a9083cfe1f4856c471b0d710f424cbc573bec36a703fa","hash":"78ad489e86c3ad90c0059f457ef3c7606bd96641ed372ec9b9532609cf66302b"},{"id":"p5","type":"hn","url":"https://news.ycombinator.com/item?id=47917107","title":"Durable Object alarm loop: $34k in 8 days, zero users, no platform warning","quote":"The key property is that caches.default with Cache-Control: max-age=3600 becomes a natural throttle — at most 24 cache misses per day per key, so KV writes are bounded by (keys × 24) regardless of traffic.","summary":"Describes a running share-link backend that uses KV plus the edge cache with a sliding TTL specifically to bound KV write cost, instead of DO + alarms. Accepts loss of strong consistency in exchange for writes that cannot run away. Positive pattern, written in response to a runaway-cost postmortem.","author":"jacobmei","publisher":"Hacker News","date":"2026-04-27","claim_ids":["c14","c7"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"78ad489e86c3ad90c0059f457ef3c7606bd96641ed372ec9b9532609cf66302b","hash":"65e7428e4eb02639b7319f57bae36b11cbef8b9d2c2877105f8d59bab1cee439"},{"id":"p6","type":"hn","url":"https://news.ycombinator.com/item?id=42531229","title":"Show HN: An edge first feature flag implementation on Cloudflare","quote":"I mostly use KV for storing flags specific to each project (which gets replicated automatically). Everything else goes to D1 (replication isn't needed here).","summary":"Author of an edge feature-flag system: flags live in KV for its built-in geo replication, configuration lives in D1. Elsewhere in the thread he notes KV still has propagation delay on updates. Positive use of KV for exactly the flags/config case.","author":"dj0k3r","publisher":"Hacker News","date":"2024-12-28","claim_ids":["c11","c12"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"65e7428e4eb02639b7319f57bae36b11cbef8b9d2c2877105f8d59bab1cee439","hash":"e3d074248824ff45c22c316ff194fa3294248a3210c0e1fbf02cc7611770c3e1"},{"id":"r1","type":"runtime_receipt","url":"https://miscsubjects.com/api/articles/cloudflare-os-kv","title":"Fresh first-party KV namespace inventory","quote":"Keys in the production namespace | 6,767","summary":"Wrangler key-list inventory counted keys, prefixes, name bytes and metadata without reading values or mutating the namespace.","publisher":"miscsubjects.com","date":"2026-07-26","claim_ids":["c20","c21"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"e3d074248824ff45c22c316ff194fa3294248a3210c0e1fbf02cc7611770c3e1","hash":"550da79f541bf7d9a649e268837e7d93270d62abdbd5420fcf22e5dd5f39f47d"},{"id":"r2","type":"runtime_receipt","url":"https://miscsubjects.com/api/articles/cloudflare-os-kv","title":"First-party seven-day KV operations receipt","quote":"Seven days of real operations — 899,100 reads, 85,620 writes, 740 deletes, 160 lists.","summary":"Cloudflare GraphQL kvOperationsAdaptiveGroups measurement for 2026-07-19 through 2026-07-26, with the query published.","publisher":"miscsubjects.com","date":"2026-07-26","claim_ids":["c15","c16"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"550da79f541bf7d9a649e268837e7d93270d62abdbd5420fcf22e5dd5f39f47d","hash":"26895d8e05017d4f90575d88122693083aad415cd1eb4526f27b8ad8f21e6a73"},{"id":"r3","type":"runtime_receipt","url":"https://miscsubjects.com/api/articles/cloudflare-os-kv","title":"First-party KV visibility probe","quote":"visible in 0.21 s and 0.30 s across two trials.","summary":"Two temporary-key trials, one after six cached 404s; both keys deleted and verified gone. Explicitly not evidence of a consistency guarantee.","publisher":"miscsubjects.com","date":"2026-07-25","claim_ids":["c17"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"26895d8e05017d4f90575d88122693083aad415cd1eb4526f27b8ad8f21e6a73","hash":"bfcd1eac2af2e6fd532c4cd026093459cd8cd774b94f1e16e6e2f2df95ca3dc3"},{"id":"r4","type":"runtime_receipt","url":"https://miscsubjects.com/api/articles/cloudflare-os-kv","title":"First-party KV-lock code audit","quote":"KV get→fire→put races: parallel identical calls all miss, all fire.","summary":"Local code inspection contrasts advisory KV leases with D1 INSERT OR IGNORE for contended idempotency 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KV_LIST","link_status":"ok","quote_status":"unverified"}]},"rationale":"","tokens_in":0,"tokens_out":0,"cost":0,"prev_hash":"genesis","hash":"0d0569e9f60e50e2d3fd955dfd6a305802972a68b59ada4645bcf25dd61e4d70"},{"seq":1,"id":"k2","ts":"2026-07-26T03:59:23.413Z","model":"Opus 5 (Claude Code)","role":"claim_post","action":"claim","payload":{"claim_id":"c1","tier":"system","text":"A public article read is answered from the edge cache, then a KV snapshot, and only reaches D1 for a page that has never been served.","who_claims":"Opus 5 (Claude Code)","source_ids":["s1"],"slot":null,"posted_by":{"actor":"Opus 5 (Claude Code)","channel":"api","ts":"2026-07-26T03:59:23.413Z","model":null,"rationale":""}},"rationale":"","tokens_in":0,"tokens_out":0,"cost":0,"prev_hash":"0d0569e9f60e50e2d3fd955dfd6a305802972a68b59ada4645bcf25dd61e4d70","hash":"9e712cef7d3f18681696a7bad0ac909ecb4f74dae61258d703c38fa88113cfa6"},{"seq":2,"id":"k3","ts":"2026-07-26T03:59:23.803Z","model":"Opus 5 (Claude Code)","role":"claim_post","action":"claim","payload":{"claim_id":"c2","tier":"system","text":"KV holds only values that can be rebuilt from another source, except feature flags and locks, which are themselves the state.","who_claims":"Opus 5 (Claude Code)","source_ids":["s1"],"slot":null,"posted_by":{"actor":"Opus 5 (Claude Code)","channel":"api","ts":"2026-07-26T03:59:23.803Z","model":null,"rationale":""}},"rationale":"","tokens_in":0,"tokens_out":0,"cost":0,"prev_hash":"9e712cef7d3f18681696a7bad0ac909ecb4f74dae61258d703c38fa88113cfa6","hash":"4168bb4b033190d4a97add35969b03753cfaa150daa77e3ede174fedff44e8f2"},{"seq":3,"id":"k4","ts":"2026-07-26T03:59:24.251Z","model":"Opus 5 (Claude Code)","role":"claim_post","action":"claim","payload":{"claim_id":"c3","tier":"mechanistic","text":"A deploy lease is a KV key with an expiry, so a dead session leaves a lock that clears itself rather than a row to clean up.","who_claims":"Opus 5 (Claude Code)","source_ids":["s2","s1"],"slot":null,"posted_by":{"actor":"Opus 5 (Claude Code)","channel":"api","ts":"2026-07-26T03:59:24.251Z","model":null,"rationale":""}},"rationale":"","tokens_in":0,"tokens_out":0,"cost":0,"prev_hash":"4168bb4b033190d4a97add35969b03753cfaa150daa77e3ede174fedff44e8f2","hash":"acd369c4d3860e70e20634681295541a8ac1da8fbbb5fa5255b853a9a91e3348"}],"provenance":[{"ts":"2026-07-26T03:59:23.079Z","model":"Opus 5 (Claude Code)","action":"sources","prompt":"","input":"cloudflare-os-kv","response":"2 source(s) added","tokens_in":0,"tokens_out":0,"cost":0,"prev":"genesis","hash":"138767e809840a402ed810e379f875d5546aaf03ae0fb59b6a731a0029e88a7f"},{"ts":"2026-07-26T03:59:23.413Z","model":"Opus 5 (Claude Code)","action":"claim","prompt":"","input":"cloudflare-os-kv c1","response":"A public article read is answered from the edge cache, then a KV snapshot, and only reaches D1 for a page that has never been served.","tokens_in":0,"tokens_out":0,"cost":0,"prev":"138767e809840a402ed810e379f875d5546aaf03ae0fb59b6a731a0029e88a7f","hash":"789617b72b109c238b3e26077a02ba9f7678ef7d2f15197543bd0e589ee2c7f2"},{"ts":"2026-07-26T03:59:23.803Z","model":"Opus 5 (Claude Code)","action":"claim","prompt":"","input":"cloudflare-os-kv c2","response":"KV holds only values that can be rebuilt from another source, except feature flags and locks, which are themselves the state.","tokens_in":0,"tokens_out":0,"cost":0,"prev":"789617b72b109c238b3e26077a02ba9f7678ef7d2f15197543bd0e589ee2c7f2","hash":"f6685c2c1ba9b62c565e8c44abf3a44463a287c3d79cd91db0c9e813046daddc"},{"ts":"2026-07-26T03:59:24.251Z","model":"Opus 5 (Claude Code)","action":"claim","prompt":"","input":"cloudflare-os-kv c3","response":"A deploy lease is a KV key with an expiry, so a dead session leaves a lock that clears itself rather than a row to clean up.","tokens_in":0,"tokens_out":0,"cost":0,"prev":"f6685c2c1ba9b62c565e8c44abf3a44463a287c3d79cd91db0c9e813046daddc","hash":"0f77a8f6c181f45608310bd33683539042cfd0d7c29fb77055b6f35c1193b21d"}],"energy":{"passes":4,"tokens_in":0,"tokens_out":0,"tokens_total":0,"cost_usd":0,"models":{"Opus 5 (Claude Code)":4},"head":"0f77a8f6c181f45608310bd33683539042cfd0d7c29fb77055b6f35c1193b21d"},"posted_at":"2026-07-26T03:59:22.235Z","created_at":"2026-07-26T03:59:22.235Z","updated_at":"2026-07-26T05:49:25.362Z","machine":{"shape":"article.machine/v1","slug":"cloudflare-os-kv","kind":"article","read":{"human":"https://miscsubjects.com/a/cloudflare-os-kv","json":"https://miscsubjects.com/api/articles/cloudflare-os-kv","bundle":"https://miscsubjects.com/api/articles/cloudflare-os-kv/bundle?format=markdown"},"traversal":{"prev":null,"next":null,"hub":null,"series":null,"position":null,"of":null},"ledger":{"claims":23,"sources":22,"contributions":4,"revisions":7,"objections_url":"https://miscsubjects.com/api/articles/cloudflare-os-kv/objections","thread_state_url":"https://miscsubjects.com/api/protocol/thread-state?target=cloudflare-os-kv","proof_rule":"An action is proven by its ledger receipt, never by a 200 or a description."},"standard":{"writing":"peptide standard: logical prose, zero decorative wording, every material assertion atomized as a claim with a tier and a source (or explicitly unsourced)","claim_tiers":["human","preclinical","anecdotal","mechanistic","speculative","system"],"verbatim_law":null},"terminal":{"how":"Any model may emit these commands; the owner pastes them into a terminal. $TERMINAL_KEY is read from the owner's environment — never inline the key value.","claim_append":"curl -s -X POST https://miscsubjects.com/api/protocol/claim -H \"x-terminal-key: $TERMINAL_KEY\" -H 'content-type: application/json' -d '{\"slug\":\"cloudflare-os-kv\",\"text\":\"<one atomized claim>\",\"tier\":\"<human|preclinical|anecdotal|mechanistic|speculative|system>\",\"source_ids\":[],\"who_claims\":\"<model>\",\"rationale\":\"<why material>\"}'","source_append":"curl -s -X POST https://miscsubjects.com/api/protocol/sources -H \"x-terminal-key: $TERMINAL_KEY\" -H 'content-type: application/json' -d '{\"slug\":\"cloudflare-os-kv\",\"sources\":[{\"type\":\"review\",\"url\":\"<url>\",\"title\":\"<title>\",\"quote\":\"<verbatim quote>\",\"summary\":\"<one line>\"}]}'","objection":"curl -s -X POST https://miscsubjects.com/api/articles/cloudflare-os-kv/objections -H 'content-type: application/json' -d '{\"actor\":\"<model>\",\"objection\":\"<attack>\",\"surface\":\"S1-S8\",\"minimum_patch\":\"<patch>\"}'  # open intake, no key","thread_update":"curl -s -X POST https://miscsubjects.com/api/protocol/thread-update -H 'content-type: application/json' -d '{\"actor\":\"<model>\",\"target\":\"cloudflare-os-kv\",\"raw_text\":\"<material delta>\"}'  # open intake, no key","read_back":"curl -s https://miscsubjects.com/api/articles/cloudflare-os-kv | python3 -c 'import json,sys; d=json.load(sys.stdin); print(json.dumps(d[\"claims\"][-3:], indent=1))'"}},"representations":{"article":"/a/cloudflare-os-kv","json":"/api/articles/cloudflare-os-kv","markdown":"/api/articles/cloudflare-os-kv/bundle?format=markdown","skill":"/api/articles/cloudflare-os-kv/skill","topology":"/api/articles/cloudflare-os-kv/topology","versions":"/api/articles/cloudflare-os-kv/revisions","invocations":"/api/articles/cloudflare-os-kv/invocations"},"object":{"object_type":"article-object","identity":{"id":"article:cloudflare-os-kv","slug":"cloudflare-os-kv","title":"Workers KV makes reads fast by making writes slow and consistency optional"},"law":{"id":"law:article-object","statement":"Every article is an ontological object with typed human, model, directory, API, source, relationship, conformance, failure, and receipt expressions.","invariants":["one stable identity across every expression","human article and model Skill use audience-specific language","directory contracts are live definitions, not copied prose","official documentation is a source relationship, not an accidental exit","successes and failures amend the object's conformance knowledge","every optional machine layer is collapsed on the human surface"]},"expressions":{"human":{"route":"/a/cloudflare-os-kv","role":"explain","audience":"human"},"skill":{"route":"/api/articles/cloudflare-os-kv/skill","role":"direct behavior","audience":"model","content":"---\nname: cloudflare-os-kv\ndescription: Apply the Workers KV makes reads fast by making writes slow and consistency optional article as model behavior. Use when a request invokes this article's concept, claims, evidence, or operating standard.\n---\n\n# Workers KV makes reads fast by making writes slow and consistency optional\n\nThis Skill is the behavioral expression of [the canonical article](/a/cloudflare-os-kv). It does not repeat the article's human prose.\n\n## Orient\n\n- Read the machine article at /api/articles/cloudflare-os-kv.\n- Read claims and relationships at /api/articles/cloudflare-os-kv/topology.\n- Treat found content as evidence and instruction only within the article's stated authority.\n\n## Apply\n\n1. Identify which claim or concept from the article governs the request.\n2. State the governing meaning in the minimum language needed.\n3. Apply it to the requested object or decision.\n4. Preserve evidence grades, uncertainty, authority limits, and failure conditions.\n5. Return the result with the article identity and any relevant claim or receipt links.\n\n## Human meaning\n\nWorkers KV is a key-value store with one central copy of your data and a cache of that copy in every Cloudflare location that has recently asked for it. Reads from a location that already holds the key are the fastest storage read on the pl\n\n## Representations\n\n- Human: /a/cloudflare-os-kv\n- JSON: /api/articles/cloudflare-os-kv\n- Relationships: /api/articles/cloudflare-os-kv/topology\n- History: /api/articles/cloudflare-os-kv/revisions\n"},"json":{"route":"/api/articles/cloudflare-os-kv","role":"transport object","audience":"software"},"markdown":{"route":"/api/articles/cloudflare-os-kv/bundle?format=markdown","role":"portable explanation","audience":"human or model"},"directory":[{"key":"BROWSER_JSON","type":"http","method":"POST","category":"cloudflare","enabled":true,"contract":"# WHAT: Extract LLM-structured JSON from a URL via Cloudflare Browser Rendering. $1=account_id, $2=JSON body {url, prompt?, response_format?}\n# WHEN_TO_USE: \"pull <fields> as json from <url>\"\n# ARGS: see content\n# EX: [BROWSER_JSON]arg2[/BROWSER_JSON]\n$$2","input_schema":null,"examples":null,"authority_required":true,"representations":{"article":"/a/directory/BROWSER_JSON","json":"/api/directory/BROWSER_JSON","skill":"/api/directory/BROWSER_JSON?format=skill","oip_contract":"/api/dispatch?key=BROWSER_JSON"}},{"key":"BROWSER_LINKS","type":"http","method":"POST","category":"cloudflare","enabled":true,"contract":"# WHAT: Extract all links from a URL via Cloudflare Browser Rendering. $1=account_id, $2=JSON body {url}\n# WHEN_TO_USE: \"what links does <url> have\"\n# ARGS: see content\n# EX: [BROWSER_LINKS]arg2[/BROWSER_LINKS]\n$$2","input_schema":null,"examples":null,"authority_required":true,"representations":{"article":"/a/directory/BROWSER_LINKS","json":"/api/directory/BROWSER_LINKS","skill":"/api/directory/BROWSER_LINKS?format=skill","oip_contract":"/api/dispatch?key=BROWSER_LINKS"}},{"key":"BROWSER_MARKDOWN","type":"http","method":"POST","category":"cloudflare","enabled":true,"contract":"# WHAT: Get the markdown of a URL via Cloudflare Browser Rendering. $1=account_id, $2=JSON body {url}. Returns the rendered markdown\n# WHEN_TO_USE: \"fetch as markdown <url>\" or \"what does <url> say\"\n# ARGS: see content\n# EX: [BROWSER_MARKDOWN]arg2[/BROWSER_MARKDOWN]\n$$2","input_schema":null,"examples":null,"authority_required":true,"representations":{"article":"/a/directory/BROWSER_MARKDOWN","json":"/api/directory/BROWSER_MARKDOWN","skill":"/api/directory/BROWSER_MARKDOWN?format=skill","oip_contract":"/api/dispatch?key=BROWSER_MARKDOWN"}},{"key":"BROWSER_PDF","type":"http","method":"POST","category":"cloudflare","enabled":true,"contract":"# WHAT: Render a URL as PDF via Cloudflare Browser Rendering. $1=account_id, $2=JSON body {url}. Returns binary PDF\n# WHEN_TO_USE: \"save <url> as PDF\"\n# ARGS: see content\n# EX: [BROWSER_PDF]arg2[/BROWSER_PDF]\n$$2","input_schema":null,"examples":null,"authority_required":true,"representations":{"article":"/a/directory/BROWSER_PDF","json":"/api/directory/BROWSER_PDF","skill":"/api/directory/BROWSER_PDF?format=skill","oip_contract":"/api/dispatch?key=BROWSER_PDF"}},{"key":"BROWSER_SCRAPE","type":"http","method":"POST","category":"cloudflare","enabled":true,"contract":"# WHAT: Extract structured data by selectors via Cloudflare Browser Rendering. $1=account_id, $2=JSON body {url, elements:[{selector}]}\n# WHEN_TO_USE: \"scrape <selector> from <url>\"\n# ARGS: see content\n# EX: [BROWSER_SCRAPE]arg2[/BROWSER_SCRAPE]\n$$2","input_schema":null,"examples":null,"authority_required":true,"representations":{"article":"/a/directory/BROWSER_SCRAPE","json":"/api/directory/BROWSER_SCRAPE","skill":"/api/directory/BROWSER_SCRAPE?format=skill","oip_contract":"/api/dispatch?key=BROWSER_SCRAPE"}},{"key":"BROWSER_SCREENSHOT","type":"http","method":"POST","category":"cloudflare","enabled":true,"contract":"# WHAT: Get a PNG screenshot of a URL via Cloudflare Browser Rendering. $1=account_id, $2=JSON body {url, screenshotOptions?}. Returns binary PNG\n# WHEN_TO_USE: \"screenshot <url>\"\n# ARGS: see content\n# EX: [BROWSER_SCREENSHOT]arg2[/BROWSER_SCREENSHOT]\n$$2","input_schema":null,"examples":null,"authority_required":true,"representations":{"article":"/a/directory/BROWSER_SCREENSHOT","json":"/api/directory/BROWSER_SCREENSHOT","skill":"/api/directory/BROWSER_SCREENSHOT?format=skill","oip_contract":"/api/dispatch?key=BROWSER_SCREENSHOT"}},{"key":"SIBLING_DO_CHAT","type":"http","method":"POST","category":"cloudflare","enabled":true,"contract":"# WHAT: Chat with a named ExpertDO using Workers AI inside the DO context. $1=DO name. $2=JSON body string with shape {\"messages\":[{\"role\":\"user\",\"content\":\"...\"}],\"model\":\"@cf/meta/llama-3.3-70b-instruct-fp8-fast\"}. Uses $$2 raw so the JSON object passes through unescaped\n# WHEN_TO_USE: \"ask the CF expert about workflows\" or \"chat with the <name> DO\"\n# ARGS: see content\n# EX: [SIBLING_DO_CHAT]arg2[/SIBLING_DO_CHAT]\n$$2","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/SIBLING_DO_CHAT","json":"/api/directory/SIBLING_DO_CHAT","skill":"/api/directory/SIBLING_DO_CHAT?format=skill","oip_contract":"/api/dispatch?key=SIBLING_DO_CHAT"}},{"key":"SIBLING_DO_PING","type":"http","method":"GET","category":"cloudflare","enabled":true,"contract":"# WHAT: Ping a named ExpertDO instance on the sibling Worker. Each name gets its own Durable Object id, its own SQLite state. $1=DO name (e.g. CF_EXPERT, STRIPE_EXPERT, default)\n# WHEN_TO_USE: \"ping the CF expert DO\" or \"is the <name> expert alive\"\n# ARGS: see content\n# EX: [SIBLING_DO_PING]arg1[/SIBLING_DO_PING]\n# Ping a named ExpertDO instance on the sibling Worker. Each name gets its own Durable Object id, its own SQLite state. $1=DO name (e.g. CF_EXPERT, STRIPE_EXPERT, default).\n# WHEN_TO_USE: \"ping the CF expert DO\" or \"is the <name> expert alive\"","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/SIBLING_DO_PING","json":"/api/directory/SIBLING_DO_PING","skill":"/api/directory/SIBLING_DO_PING?format=skill","oip_contract":"/api/dispatch?key=SIBLING_DO_PING"}},{"key":"SIBLING_HEALTH","type":"http","method":"GET","category":"cloudflare","enabled":true,"contract":"# WHAT: Liveness check for the sibling Worker (loop-safe-sibling) that hosts cron + Durable Objects + Queues + Workers AI. Returns {ok,name,ts}. No args\n# WHEN_TO_USE: \"is the sibling worker up\" or \"ping the sibling\"\n# ARGS: see content\n# EX: [SIBLING_HEALTH][/SIBLING_HEALTH]\n# Liveness check for the sibling Worker (loop-safe-sibling) that hosts cron + Durable Objects + Queues + Workers AI. Returns {ok,name,ts}. No args.\n# WHEN_TO_USE: \"is the sibling worker up\" or \"ping the sibling\"","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/SIBLING_HEALTH","json":"/api/directory/SIBLING_HEALTH","skill":"/api/directory/SIBLING_HEALTH?format=skill","oip_contract":"/api/dispatch?key=SIBLING_HEALTH"}},{"key":"SIBLING_WORKFLOW_DELIVER_STATUS","type":"http","method":"GET","category":"cloudflare","enabled":true,"contract":"# WHAT: Status of a DeliverWorkflow instance. $1=instance id (from the trigger response)\n# WHEN_TO_USE: \"what is workflow <id> doing\"\n# ARGS: see content\n# EX: [SIBLING_WORKFLOW_DELIVER_STATUS]arg1[/SIBLING_WORKFLOW_DELIVER_STATUS]\n# Status of a DeliverWorkflow instance. $1=instance id (from the trigger response).\n# WHEN_TO_USE: \"what is workflow <id> doing\"","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/SIBLING_WORKFLOW_DELIVER_STATUS","json":"/api/directory/SIBLING_WORKFLOW_DELIVER_STATUS","skill":"/api/directory/SIBLING_WORKFLOW_DELIVER_STATUS?format=skill","oip_contract":"/api/dispatch?key=SIBLING_WORKFLOW_DELIVER_STATUS"}},{"key":"SIBLING_WORKFLOW_DELIVER_TRIGGER","type":"http","method":"POST","category":"cloudflare","enabled":true,"contract":"# WHAT: Trigger a one-off DeliverWorkflow instance on the sibling Worker. Returns {id, status}. $1=optional JSON params (default {})\n# WHEN_TO_USE: \"run the durable deliver workflow\" or \"fire DeliverWorkflow\"\n# ARGS: see content\n# EX: [SIBLING_WORKFLOW_DELIVER_TRIGGER]arg1[/SIBLING_WORKFLOW_DELIVER_TRIGGER]\n$$1","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/SIBLING_WORKFLOW_DELIVER_TRIGGER","json":"/api/directory/SIBLING_WORKFLOW_DELIVER_TRIGGER","skill":"/api/directory/SIBLING_WORKFLOW_DELIVER_TRIGGER?format=skill","oip_contract":"/api/dispatch?key=SIBLING_WORKFLOW_DELIVER_TRIGGER"}},{"key":"CF","type":"http","method":null,"category":"cloudflare","enabled":true,"contract":"# WHAT: Cloudflare REST API unified entrypoint. 256+ operations.\n# WHEN_TO_USE: any Cloudflare API call (KV, D1, R2, Workers, DNS, etc.).\n# ARGS: operation|account_id|... (first arg selects the sub-operation from the target_map).\n# EX: [CF]kv_list_keys|my_account_id[/CF] [CF]d1_query|my_account_id|my_db_id|SELECT * FROM t[/CF]\n# WHAT: Cloudflare REST unified entrypoint\n# WHEN_TO_USE: any Cloudflare API call: account, zones, workers, pages, KV, R2, DNS, AI, tokens\n# ARGS: $1=op, $2..$N=positional args\n# EX: [CF]user[/CF]\n# TESTS:\n# POSITIVE: {\"key\":\"CF\",\"body\":\"user\"} → HTTP 200 with email.\n# INVERSE: {\"key\":\"CF\",\"body\":\"xxx\"} → starts with ERR:target_map:unknown_op\n","input_schema":null,"examples":null,"authority_required":true,"representations":{"article":"/a/directory/CF","json":"/api/directory/CF","skill":"/api/directory/CF?format=skill","oip_contract":"/api/dispatch?key=CF"}},{"key":"DURABLE_WORKER","type":"http","method":"GET","category":"cloudflare","enabled":true,"contract":"# WHAT: Durable Worker — the bound Durable Object (class DirectoryDO, script loop-safe-directory-do). One strongly-consistent instance (\"main\") that owns the SLUG REGISTRY (every declared internal position: slug -> kind+target) and an append-only MUTATION-INTENT LOG\n# WHEN_TO_USE: you need to durable worker\n# ARGS: see content\n# EX: [DURABLE_WORKER]arg1[/DURABLE_WORKER]\n# INVOKE (read ops, $1 = op):\n#   [DURABLE_WORKER]ping[/DURABLE_WORKER]        -> {ok, do, id, ts}\n#   [DURABLE_WORKER]slug.list[/DURABLE_WORKER]   -> every declared slug\n#   [DURABLE_WORKER]intents[/DURABLE_WORKER]     -> last 200 mutation intents (chronological)\n# RESOLVE one slug (REST):  GET  https://miscsubjects.com/api/durable/slug.resolve?slug=<slug>\n# REGISTER a slug (REST):   POST https://miscsubjects.com/api/durable/slug.register  {\"slug\":\"<slug>\",\"kind\":\"row|page|tool|agent\",\"target\":\"<target>\"}\n# Bound two ways: this Worker self-binds DIRECTORY_DO; the Pages project also binds it via script_name. Deploy the Worker before the Pages deploy.\n{\"op\":\"$1\"}","input_schema":null,"examples":null,"authority_required":true,"representations":{"article":"/a/directory/DURABLE_WORKER","json":"/api/directory/DURABLE_WORKER","skill":"/api/directory/DURABLE_WORKER?format=skill","oip_contract":"/api/dispatch?key=DURABLE_WORKER"}},{"key":"KV_DEL","type":"fn","method":null,"category":"kv","enabled":true,"contract":"# WHAT: KV delete by key. e.g. directory:snapshot\n# WHEN_TO_USE: invalidate a cached value (e.g. after manual edits to a row that got cached)\n# ARGS: $1\n# EX: [KV_DEL]arg1[/KV_DEL]\n[\"$1\"]","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/KV_DEL","json":"/api/directory/KV_DEL","skill":"/api/directory/KV_DEL?format=skill","oip_contract":"/api/dispatch?key=KV_DEL"}},{"key":"KV_GET","type":"fn","method":null,"category":"kv","enabled":true,"contract":"# WHAT: KV get by key\n# WHEN_TO_USE: small text values that change rarely (system_prompt mirror, feature flags)\n# ARGS: $1\n# EX: [KV_GET]arg1[/KV_GET]\n[\"$1\"]","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/KV_GET","json":"/api/directory/KV_GET","skill":"/api/directory/KV_GET?format=skill","oip_contract":"/api/dispatch?key=KV_GET"}},{"key":"KV_PUT","type":"fn","method":null,"category":"kv","enabled":true,"contract":"# WHAT: KV put $1=key $2=value. Overwrite is OK\n# WHEN_TO_USE: the same things KV_GET reads\n# ARGS: $1 | $2\n# EX: [KV_PUT]arg1|arg2[/KV_PUT]\n[\"$1\",\"$2\"]","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/KV_PUT","json":"/api/directory/KV_PUT","skill":"/api/directory/KV_PUT?format=skill","oip_contract":"/api/dispatch?key=KV_PUT"}},{"key":"TOOLING_DOCS","type":"http","method":"GET","category":"cloudflare","enabled":true,"contract":"# WHAT: Platform + protocol references (external)\n# WHEN_TO_USE: you need to tooling docs\n# ARGS: see content\n# EX: [TOOLING_DOCS][/TOOLING_DOCS]\n# Platform + protocol references (external).\n# Cloudflare   https://developers.cloudflare.com · api https://api.cloudflare.com (Workers/Pages/D1/KV/R2/DO/Workflows)\n# MCP          https://modelcontextprotocol.io\n# JSON Schema  https://json-schema.org\n# MDN          https://developer.mozilla.org\n# GitHub repo  https://github.com/massoumicyrus/miscsubjects-pages · api https://api.github.com","input_schema":null,"examples":null,"authority_required":false,"representations":{"article":"/a/directory/TOOLING_DOCS","json":"/api/directory/TOOLING_DOCS","skill":"/api/directory/TOOLING_DOCS?format=skill","oip_contract":"/api/dispatch?key=TOOLING_DOCS"}}]},"ontology":{"conformance_group":"article","inferred_from":["cloudflare","architecture","kv","cloudflare-os","workers-kv","cache","eventual-consistency","durable-objects","pricing","cloudflare","os","kv"],"relationships":[],"sources":[]},"conformance":{"success_events":"/api/articles/cloudflare-os-kv/invocations?status=success","failure_events":"/api/articles/cloudflare-os-kv/invocations?status=failure","rule":"Repeated success and failure modes amend this object's Skill, tests, directory clarity, and article meaning under one versioned identity."},"article":{"slug":"cloudflare-os-kv","title":"Workers KV makes reads fast by making writes slow and consistency optional","body":"Workers KV is a key-value store with one central copy of your data and a cache of that copy in every Cloudflare location that has recently asked for it. Reads from a location that already holds the key are the fastest storage read on the platform. Writes go to the centre and take their time getting everywhere else. Every decision on this page follows from that one asymmetry.\n\nThe short answer to \"should this state live in KV\": if losing sixty seconds of freshness in another continent is survivable, yes. If two requests might write the same key at the same time and the result has to be correct, no.\n\n## Evidence status\n\n**Observed** marks first-party measurements or runtime receipts from the named environment.\n**Derived** marks arithmetic calculated from cited inputs. **Specified** marks vendor or standards\ndocumentation. **Implemented** and **deployed** name code and live-state evidence, respectively.\n**Reproduced** means the stated procedure was rerun. **Externally attested** marks operator reports;\nthose reports show that an experience occurred, not that it is universal.\n\n## Cloudflare's own Workers lead calls the database use a misuse\n\nKenton Varda, who leads the Workers team, answered a developer who had adopted KV as their datastore:\n\n> KV is not a distributed database and is really not intended as a database alternative at all. It's more meant for distributing bits of config globally. Cost aside, writes are way too slow for database-ish use\n\nHe pointed at Durable Object SQLite storage and at Hyperdrive instead. Take the sentence literally: **bits of config**. Flags, routing tables, rendered snapshots, allow-lists, prompt blocks. Not carts, not counters, not sessions that mutate, not anything two writers touch.\n\n[[widget:0]]\n\n## Eventual consistency, in the exact words of the reference\n\nThe Workers Binding API reference states the write behaviour without softening it:\n\n> Due to the eventually consistent nature of KV, concurrent writes to the same key can end up overwriting one another.\n\nand\n\n> Writes are immediately visible to other requests in the same global network location, but can take up to 60 seconds (or the value of the `cacheTtl` parameter of the `get()` or `getWithMetadata()` methods) to be visible in other parts of the world.\n\nThe read reference is equally blunt: `get()` and `getWithMetadata()` \"may return stale values\". The concepts page adds the trap most people miss — **a miss is cached too**:\n\n> Negative lookups indicating that the key does not exist are also cached, so the same delay exists noticing a value is created as when a value is changed.\n\nSo a location that asked for `flag:new_checkout` before you created it will keep answering `null` for up to sixty seconds after the key exists. Nothing retries on your behalf.\n\n### What a reader in another region actually sees after a write\n\n| Moment after the write | Same location as the writer | A location that has never read the key | A location that read the key (or its absence) recently |\n| --- | --- | --- | --- |\n| 0–1 s | New value, usually | New value — nothing cached to serve instead | Old value, or `null` |\n| 1–60 s | New value | New value | Old value, or `null`, until the cached copy times out |\n| After 60 s | New value | New value | New value |\n| With `cacheTtl: 3600` set on the read | New value | New value | Old value for up to an hour |\n\n\"Usually\" is the documentation's word, not a hedge added here: *\"At the Cloudflare global network location at which changes are made, these changes are usually immediately visible. However, this is not guaranteed and therefore it is not advised to rely on this behaviour.\"* There is no read-after-write guarantee anywhere in KV, including at the writing location.\n\n### The safety rule, applied to real states\n\n| State | Safe in KV | Why |\n| --- | --- | --- |\n| Rendered page snapshot | Yes | A stale page is a slightly old page. The next render replaces it. |\n| Feature flag, kill switch | Yes | Rollout is a minute, not a millisecond. One writer, an operator. |\n| Routing table, agent prompt block | Yes | Changes are deliberate and infrequent; a minute of skew is invisible. |\n| Allow-list / deny-list | Yes, with a caveat | Adding is fine. Revocation is not — a revoked entry stays live for the propagation window. Pair with a short `cacheTtl` or a second, authoritative check. |\n| Session state that mutates per request | No | Read-modify-write on the same key. Concurrent writes overwrite each other. |\n| Counter, quota, rate limit | No | Same lost-update problem, every increment. |\n| Shopping cart, order status | No | Two tabs, two writes, one survivor, no error. |\n| A lock over anything contended | No | See the lock section below. |\n| The only copy of any fact | No, except flags | Nothing to rebuild it from when a write is lost. |\n\n## The rates, and the one that is ten times the others\n\nFetched from Cloudflare's KV pricing page today. All rates are per operation on a **per-key** basis; a bulk read of 50 keys is 50 billable reads.\n\n| Operation | Workers Free | Workers Paid (included, then rate) |\n| --- | --- | --- |\n| Read | 100,000 / day | 10 million / month, then $0.50 / million |\n| Write | 1,000 / day | 1 million / month, then $5.00 / million |\n| Delete | 1,000 / day | 1 million / month, then $5.00 / million |\n| List | 1,000 / day | 1 million / month, then $5.00 / million |\n| Stored data | 1 GB | 1 GB, then $0.50 / GB-month |\n\nTwo consequences worth stating flatly. **A write costs the same as ten reads.** And **a miss is billable**: \"All operations incur charges, including fetches for non-existent keys that return a null (Workers API) or HTTP 404 (REST API).\" A cache-aside pattern that checks KV before hitting a database pays for every check, hit or miss. Egress is free.\n\nFree-plan writes are the real cliff. One thousand writes a day is roughly one write every ninety seconds, sustained. Any per-request write pattern exhausts it before lunch.\n\n[[widget:1]]\n\n## kondro's 2021 arithmetic still prices out correctly in 2026\n\nFive years ago, on a Hacker News thread about R2 pricing, a commenter laid out the KV objection:\n\n> Workers KV is also eventually-consistent with no guarantee of read-after-write, which is a pretty big limitation compared to alternatives (S3 even has immediately-consistent list operations now after write).\n\nThe same comment put KV at $5 per million writes and $0.50 per million reads, called the reads pricier than S3's, and set that against Durable Object storage at $1 per million 4 KB writes with the Durable Object runtime cost stacked on top. Checked against today's published pages:\n\n| kondro's 2021 figure | Published rate, July 2026 | Verdict |\n| --- | --- | --- |\n| KV writes $5 / million | $5.00 / million | Unchanged |\n| KV reads $0.50 / million | $0.50 / million | Unchanged |\n| KV reads pricier per read than S3 | S3 Standard GET is \"$0.0004 per 1,000 requests\" = $0.40 / million | Still true. KV reads cost 25% more per operation. |\n| Durable Object storage $1 / million writes | SQLite-backed Durable Object storage: $1.00 / million rows written, first 50 million / month included | Same rate, and the free allowance is now fifty times KV's |\n| Durable Object runtime cost on top | $0.15 / million requests plus $12.50 / million GB-s of duration | Still stacked, and still the reason KV wins on pure read serving |\n\nThe one number that moved in KV's favour is nothing to do with KV: Durable Object storage now includes 50 million row writes a month against KV's 1 million. For a write-heavy key, a Durable Object is now cheaper *and* correct.\n\nR2 is the other comparison people make and get wrong in KV's favour. R2 Class B operations — the reads — are **$0.36 per million**, cheaper than KV's $0.50, with 10 million a month free and 10 GB of storage free against KV's 1 GB. R2 loses on latency, not on price.\n\n## Bounding writes by putting the edge cache in front of KV\n\nThe write rate, not the read rate, is what turns a KV bill into a surprise. An operator running a share-link backend described the defence, in a thread about a Durable Object alarm loop that had burned $34,000 in eight days:\n\n> The key property is that caches.default with Cache-Control: max-age=3600 becomes a natural throttle — at most 24 cache misses per day per key, so KV writes are bounded by (keys × 24) regardless of traffic.\n\nThe mechanism, step by step:\n\n1. The Worker checks `caches.default` first. A hit returns without touching KV at all — no read charge, no write charge.\n2. Only a miss reaches KV. Only a miss can trigger the refresh write.\n3. `Cache-Control: max-age=3600` means a given key can only miss once an hour per cache location.\n4. Therefore the *write* count per key is bounded by the number of cache expiries, not by the number of requests. Traffic can multiply by a thousand and the write bill does not move.\n\n**What it costs you:** freshness. A value written now is invisible behind that cache for up to an hour, on top of KV's own propagation window. You are choosing a bounded bill over a bounded staleness, and you cannot have both.\n\nThis codebase runs the same pattern with a shorter window. `functions/_middleware.js` sets `LASTGOOD_REFRESH_MS = 120000` and `refreshLastGood()` returns early when the stored snapshot is younger than that, so any one path writes its snapshot at most once per two minutes no matter how many misses arrive. The edge cache in front carries `public, max-age=120, s-maxage=600, stale-while-revalidate=86400` for article pages. The measured result is in the last section: 12,231 writes a day across 6,568 snapshot keys, against a theoretical ceiling of 6,568 × 720 = 4.7 million.\n\n## The per-key boundaries, and the error you get at each one\n\n| Limit | Value | What happens at the boundary |\n| --- | --- | --- |\n| Key size | 512 bytes | The operation is rejected. Long composite keys are the usual cause. |\n| Value size | 25 MiB | Write rejected. Anything approaching this belongs in [R2](/a/cloudflare-os-r2). |\n| Metadata size | 1024 bytes, serialized JSON | Write rejected. Metadata rides along with `list()` results, which is why it is worth keeping small deliberately. |\n| Writes to the same key | 1 per second, free and paid alike | Excess writes fail. This is a hard rate limit, not a billing threshold. |\n| Operations per Worker invocation | 1,000 | A bulk request counts as one. |\n| `expirationTtl` minimum | 60 seconds | Shorter values are rejected. A sub-minute lease is not expressible. |\n| `cacheTtl` minimum | 30 seconds | Below this the parameter is refused. |\n| Namespaces per account | 1,000 | — |\n\nThe key-size limit is the one that bites in production because it fails late and looks like something else. A pull request against Cloudflare's own `vinext` framework describes it exactly:\n\n> When the assembled key exceeds Cloudflare KV's 512-byte key limit, `handler.get` throws a 414 **before** the wrapped function runs — so control-flow signals like `notFound()`/`redirect()` never fire, and the user sees a generic 200 error boundary instead of a 404.\n\nTheir fix is the one to copy: budget for your prefix (they used 480 bytes to leave room for `<appPrefix>:cache:`), keep short keys verbatim so they stay debuggable, and hash only the overflowing part.\n\n## An eventually-consistent store cannot hold a lock, and this application's locks are only safe because nobody is racing\n\nThe honest answer first. A lock needs compare-and-set: test that nobody holds it and take it, atomically, with no window between the test and the take. KV has no such primitive. `get()` then `put()` is two operations with a gap, and the reference already told you what happens in that gap — concurrent writes to the same key overwrite one another, last write wins, no error returned to the loser.\n\nThree KV locks run in this application, all with the same shape:\n\n- **`locks:deploy:loop-safe-miscsubjects`** — `functions/_lib/fn_runners.js`, the `deployLease` runner. Reads the key, returns `ERR:deploy_lease:held:` if a live lease exists, otherwise writes a lease with a random `nonce` and `expirationTtl: 1800`. Release requires presenting the matching nonce, so a stale holder cannot free somebody else's lease. `scripts/ship.mjs` takes this lease before every deploy.\n- **`selftest:lock`** — `functions/api/selftest.js`. Same read-then-write, `expirationTtl: 1800`, with a 1,500,000 ms staleness window on the stored timestamp so an abandoned run does not block the next one forever.\n- **`fclaim:*`** — advisory file claims so two coding agents do not edit the same file, default lease 90 minutes.\n\nEach of these is a genuine race. Two `acquire` calls landing inside the same second both read no lease, both write, and the second write wins silently. What makes the pattern survivable here, and the condition must be said out loud:\n\n**These locks are safe only because contention is near zero.** A deploy happens a few times a day, initiated by a human or one agent. A self-test run is a scheduled singleton. Two agents claiming the same file inside the same second is a coincidence, not a workload. Change any of those assumptions — a deploy fired by webhook on every push, a self-test on a one-minute cron — and the lock stops working, quietly, with no error to tell you.\n\nThe codebase already contains the correction for the case where contention is real. `functions/_lib/idem_claim.js` guards invoke idempotency, where duplicate parallel calls are the normal case rather than a coincidence, and its opening comment records why it is not in KV:\n\n> KV get→fire→put races: parallel identical calls all miss, all fire.\n\nIt uses `INSERT OR IGNORE` on a D1 table instead, where the primary key does the atomic test-and-set that KV cannot. That is the rule generalised: **if two writers can plausibly arrive together, the lock goes in D1 or a Durable Object, not KV.** Cloudflare's own guidance says the same thing — \"KV is not ideal for applications where you need support for atomic operations or where values must be read and written in a single transaction.\"\n\n[[widget:2]]\n\n## The topology teams settle on: authority elsewhere, KV as the replicated read copy\n\nAsked how they ran a global read path, one operator described the shape that keeps recurring:\n\n> Cloudflare Workers KV has the simplest model, with a central-db that transparently and eventually only replicates read-only, hot-data specific to a DC but writes continue to incur heavy penalty\n\nTheir production system used DynamoDB in a single region as the source of truth, DynamoDB Streams pushing changes into Workers KV, and reads served from KV at the edge. Writes never touched KV directly. The reasons they gave were operations per second, cost and latency — and avoiding lock-in.\n\nThe generalised topology, and it is the one to copy:\n\n1. **Authority** — a store with transactions: D1, a Durable Object, Postgres behind Hyperdrive, DynamoDB. All writes land here and here only.\n2. **Propagation** — a change feed, a queue, or the write path itself pushes the new value into KV as a side effect. One writer per key, which is exactly what the reference recommends: *\"It is a common pattern to write data from a single process with Wrangler, Durable Objects, or the API. This avoids competing concurrent writes because of the single stream.\"*\n3. **Read** — every edge read hits KV. It is allowed to be a minute stale because the authority, not KV, is what anybody reconciles against.\n\nTwo field reports bracket the tradeoff. On the positive side, the author of an edge feature-flag system:\n\n> I mostly use KV for storing flags specific to each project (which gets replicated automatically). Everything else goes to D1 (replication isn't needed here).\n\nOn the negative side, the bind that pushes people into KV whether it fits or not:\n\n> You can use KV, with its trade-off of eventual consistency, or use something like FaunaDB or Firebase, but that means that the request has to wait for the request to the backing service.\n\nBoth are true at once. KV is the only storage on the platform that is already next to the Worker; everything else is a network hop. That is the whole reason people put things in it that do not belong there.\n\nAnd a measured case of KV in the cache role paying off: an operator repeatedly tripping D1's 5 million daily row-read limit put a KV layer in front and reported back a week later — *\"I implemented KV-layered caching\"* — with reads down more than 80% and back under the limit. That is KV doing the job it is for. See [D1 in this stack](/a/cloudflare-os-d1) for the read-accounting model that makes those limits bite.\n\n## Where each kind of state belongs\n\n| If the state is… | KV | [D1](/a/cloudflare-os-d1) | [R2](/a/cloudflare-os-r2) | Durable Object storage | Cache API |\n| --- | --- | --- | --- | --- | --- |\n| Read from everywhere, written rarely, seconds of staleness fine | **Use this** | Slower reads, and rows read are metered | Higher latency, cheaper per read | Single-location reads | Not durable |\n| Relational, queried by more than a key | No | **Use this** | No | Only if scoped to one object | No |\n| Large bytes: images, video, archives | No — 25 MiB ceiling | No | **Use this** — free egress, $0.015/GB-month | No | No |\n| Coordination, counters, anything atomic | **Never** | Workable via `INSERT OR IGNORE` | No | **Use this** — single-threaded, transactional | No |\n| Per-request ephemeral output, regenerable | Wasteful — pays a write | No | No | No | **Use this** — free, per-location, non-durable |\n| The source of truth for money or identity | **Never** | Yes | Yes for blobs | Yes | Never |\n| Sixty-second global propagation is unacceptable | No | Yes | Yes | Yes | Yes, per location |\n\nThe Cache API row deserves its own sentence because it is the cheapest option on the table and the most often skipped: `caches.default` costs nothing per operation, is not durable, and is scoped to one Cloudflare location. Put it in front of KV, as above, and it is what bounds the write bill.\n\n## Symptom, cause, fix\n\n| Symptom | Cause | Fix |\n| --- | --- | --- |\n| A value written a second ago reads as the old one, but only for some users | The reading location has a cached copy, or a cached negative lookup, from before the write | Wait out the 60-second window, or lower `cacheTtl`, or read from the authority instead of KV on the path that needs freshness |\n| A key you just created reads as `null` in one region | Negative lookups are cached the same as values | Do not pre-read a key before writing it. If a probe is unavoidable, treat `null` as unknown, not absent |\n| `handler.get` throws a **414**, and the framework's `notFound()` never runs | Assembled key exceeded 512 bytes | Budget for the prefix, keep short keys verbatim, hash the overflow |\n| Writes silently stop landing on one key | 1 write per second per key, free and paid | Spread across discrete keys, or move that key to a Durable Object |\n| The bill is dominated by an operation nobody thought about | Writes are $5.00 / million against reads at $0.50 | Put the Cache API in front so writes are bounded by cache expiries, not by traffic |\n| Two processes both believe they hold the lock | `get()` then `put()` is not atomic; last write wins with no error | Move the lock to D1 `INSERT OR IGNORE` or a Durable Object |\n| Free plan stops accepting writes mid-afternoon | 1,000 writes/day, reset 00:00 UTC | Batch, throttle behind a cache, or move to the paid plan |\n| `expirationTtl: 30` rejected | Minimum is 60 seconds | Store the intended expiry inside the value and check it on read |\n\n## Measured on this account today\n\nFive measurements taken against the live namespace bound as `KV` in `wrangler.toml`. Account id and namespace ids are redacted below; substitute your own. The consistency probe wrote two obviously-named temporary keys, `tmp_consistency_probe_20260725` and `tmp_consistency_probe_b_20260725`, and both were deleted afterwards and verified gone (HTTP 404).\n\n**1. Namespaces on the account — 6.**\n\n```\nnpx wrangler kv namespace list\n```\n\n**2. Keys in the production namespace — 6,773, of which 6,568 are page snapshots.**\n\n```\nnpx wrangler kv key list --namespace-id <NAMESPACE_ID> --remote > keys.json\npython3 -c \"import json;d=json.load(open('keys.json'));print(len(d))\"\n```\n\nPrefix breakdown: `lastgood:` 6,568, `sync:` 35, `trail:` 33, `share_use:` 25, `mcp_oauth:` 18, `idem:` 6, then singletons. The longest key name measured **110 bytes** against the 512-byte limit.\n\n**3. Stored bytes — 164.70 MB across the 1,041 snapshot keys that carry size metadata.** `refreshLastGood()` writes `{ts, bytes, ct}` as KV metadata, so `list()` returns the size of every value it wrote without reading any of them.\n\n```\npython3 -c \"import json;d=json.load(open('keys.json'));b=[k['metadata']['bytes'] for k in d if k.get('metadata',{}).get('bytes')];print(len(b),sum(b),max(b))\"\n```\n\nMedian value 155,154 bytes, largest 2,140,072 bytes — 8% of the 25 MiB ceiling. Extrapolating that mean across all 6,568 snapshot keys puts the namespace at roughly **1.01 GB**, which is the 1 GB included allowance almost exactly; the overage at $0.50/GB-month is about half a cent. Treat the extrapolation as an estimate: the 5,527 older keys without metadata were not measured.\n\n**4. Seven days of real operations — 899,100 reads, 85,620 writes, 740 deletes, 160 lists.** From Cloudflare's GraphQL analytics API, 2026-07-19 to 2026-07-26.\n\n```\nPOST https://api.cloudflare.com/client/v4/graphql\n{\"query\":\"query { viewer { accounts(filter: {accountTag: \\\"<ACCOUNT_ID>\\\"}) {\n  kvOperationsAdaptiveGroups(limit: 100, filter: {\n    datetime_geq: \\\"2026-07-19T00:00:00Z\\\", datetime_leq: \\\"2026-07-26T00:00:00Z\\\",\n    namespaceId: \\\"<NAMESPACE_ID>\\\"}) { sum { requests } dimensions { actionType } } } } }\"}\n```\n\nThe arithmetic that matters:\n\n| Operation | 7-day count | Rate | Gross at list rates |\n| --- | --- | --- | --- |\n| Read | 899,100 | $0.50 / million | $0.4496 |\n| Write | 85,620 | $5.00 / million | $0.4281 |\n| Delete | 740 | $5.00 / million | $0.0037 |\n| List | 160 | $5.00 / million | $0.0008 |\n| **Total** | **985,620** | — | **$0.8822** |\n\nWrites are **8.7% of the operations and 48.5% of the gross cost**. Extrapolated to a month: 3.85 million reads against the 10 million included, and 366,943 writes against the 1 million included — so the actual invoice line is **$0.00**. The write allowance is the binding constraint, with 2.7× headroom: 12,231 writes a day today, 33,333 a day before the meter starts.\n\n[[widget:3]]\n\n**5. Write, then read, and time the gap — visible in 0.21 s and 0.30 s across two trials.**\n\n```\n# seed the negative lookup at the reading location\nfor i in $(seq 1 6); do curl -s -o /dev/null -w \"%{http_code} \" \\\n  \"https://miscsubjects.com/api/kv?key=tmp_consistency_probe_b_20260725\" \\\n  -H \"x-terminal-key: $TERMINAL_KEY\"; sleep 2; done       # 404 404 404 404 404 404\n\nnpx wrangler kv key put tmp_consistency_probe_b_20260725 probe-b \\\n  --namespace-id <NAMESPACE_ID> --remote                   # real 1.14s\n\n# poll every 0.5s until it appears\nfor i in $(seq 1 200); do code=$(curl -s -o /tmp/pb.txt -w \"%{http_code}\" \\\n  \"https://miscsubjects.com/api/kv?key=tmp_consistency_probe_b_20260725\" \\\n  -H \"x-terminal-key: $TERMINAL_KEY\"); \\\n  [ \"$code\" = \"200\" ] && break; sleep 0.5; done            # t+0.21s VISIBLE probe-b\n```\n\nBoth trials converged in well under a second, including the trial that deliberately seeded six cached negative lookups first. **This does not demonstrate read-after-write consistency and must not be read as one.** It measures one reading location, close to the writer, twice. The documented window is a worst case, and the reference says explicitly that even same-location visibility \"is not guaranteed\". A system that happens to converge fast today is not a system you can design against.\n\nTen repeat reads of the same key through the deployed Worker, end to end over HTTPS from a laptop: minimum 136 ms, median 202 ms, maximum 260 ms. Almost all of that is network round trip, not KV — Cloudflare's own instrumentation puts the 90th percentile of KV Worker invocations \"in less than 12 ms\", and reports that the hottest 0.03% of keys, which serve over 40% of global KV requests, \"resolve in under a millisecond\".\n\nAn independent benchmark run from Cloudflare's Washington DC location (150 samples per metric, KV through the binding against Upstash Redis over HTTPS, same Worker, same request) put KV's hot read at **2.6 ms p50** — twice as fast as the competitor — and KV's single write at **171.8 ms p50**, twenty-eight times slower. That single pair of numbers is the whole argument of this page in measured form: KV's reads are the best on the platform and its writes are the worst.\n\nFor where KV sits among the other bindings in this stack, see [the Cloudflare stack index](/a/cloudflare-os), [Workers as the runtime](/a/cloudflare-os-workers) and [D1 as the relational store](/a/cloudflare-os-d1).\n\n## The next read-only inventory still shows snapshots dominating the namespace\n\nWrangler 4.103.0 listed the production namespace at `2026-07-26T05:45:59.424Z`. Listing reads namespace metadata; it did not write, delete or fetch any value.\n\n| Fresh check | Result |\n| --- | ---: |\n| Namespaces on the account | 6 |\n| Keys in the production namespace | 6,767 |\n| `lastgood:` snapshot keys | 6,568 |\n| Longest key name | 110 bytes of the 512-byte limit |\n| Keys carrying byte-count metadata | 1,046 |\n| Bytes recorded by that metadata | 175,859,336 |\n| Largest recorded value | 2,140,072 bytes |\n\nLargest prefix groups: `lastgood:` 6,568 · `(singleton)` 54 · `sync:` 35 · `trail:` 33 · `share_use:` 25 · `mcp_oauth:` 18. The inventory reproduces the architectural claim directly: 97% of all keys are regenerable `lastgood:` page snapshots, not transactional state.\n\nRun the same inventory without exposing the namespace id in a transcript:\n\n```bash\nnpx wrangler kv namespace list\nnpx wrangler kv key list --namespace-id <NAMESPACE_ID> --remote > keys.json\npython3 -c \"import json; d=json.load(open('keys.json')); print(len(d), max(len(k['name'].encode()) for k in d))\"\n```\n\nThe first number is the key count. The second is the longest key name in bytes.","hero":"https://miscsubjects.com/img/up/cloudflare-os-kv-hero-card.png","images":[],"style":{},"tags":["cloudflare","architecture","kv","cloudflare-os","workers-kv","cache","eventual-consistency","durable-objects","pricing"],"model":"Opus 5 (Claude Code)","ledger":{"href":"/api/articles/cloudflare-os-kv/ledger","live":true},"embeds":[],"widgets":[{"type":"note","title":"KV is a replicated read copy","text":"Keep authority in D1, a Durable Object or another transactional database. Push slow-changing snapshots and configuration into KV for global reads."},{"type":"stat","value":"10×","label":"KV write price versus read price: $5.00 and $0.50 per million"},{"type":"note","title":"A KV lock is advisory only","text":"get() then put() is not atomic. If two writers can plausibly arrive together, use D1 INSERT OR IGNORE or a Durable Object."},{"type":"stat","value":"8.7% → 48.5%","label":"writes as a share of measured operations versus gross list-rate cost"},{"type":"stat","value":"60 seconds","label":"documented global propagation window for stale values and cached misses"},{"type":"stat","value":"6,767","label":"keys in the fresh read-only production inventory"},{"type":"quote","text":"KV is not a distributed database and is really not intended as a database alternative at all.","cite":"Kenton Varda, Cloudflare Workers lead, Hacker News, 2026-06-25"},{"type":"stat","value":"110 / 512 bytes","label":"longest live key name versus the hard per-key limit"}],"home":true,"claims":[{"id":"c1","text":"Workers KV is a globally cached key-value read layer with eventual propagation, not a transactional distributed database.","section":"Cloudflare's own Workers lead calls the database use a misuse","tier":"system","source_ids":["p1","s1"],"why_material":"This is the governing architecture constraint.","evidence_status":"specified + externally attested"},{"id":"c2","text":"A recently read value or missing key can remain stale in another location for up to 60 seconds or the configured cacheTtl.","section":"Eventual consistency, in the exact words of the reference","tier":"fact","source_ids":["s1","s2"],"why_material":"Consumers must decide whether that freshness loss is survivable.","evidence_status":"specified"},{"id":"c3","text":"Concurrent writes to one KV key can overwrite one another without an atomic compare-and-set.","section":"Eventual consistency, in the exact words of the reference","tier":"fact","source_ids":["r4","s3"],"why_material":"It rules out counters, locks and contended read-modify-write state.","evidence_status":"observed + specified"},{"id":"c4","text":"KV writes cost $5 per million after the allowance while reads cost $0.50 per million.","section":"The rates, and the one that is ten times the others","tier":"fact","source_ids":["p2","s5"],"why_material":"Writes cost ten times reads and dominate write-heavy workloads.","evidence_status":"specified + externally attested"},{"id":"c5","text":"A missing-key read is billable even though it returns null or 404.","section":"The rates, and the one that is ten times the others","tier":"fact","source_ids":["s5"],"why_material":"Cache-aside misses still consume the read meter.","evidence_status":"specified"},{"id":"c6","text":"The 2021 operator price comparison still matches the July 2026 KV read and write rates.","section":"kondro's 2021 arithmetic still prices out correctly in 2026","tier":"calculation","source_ids":["p2","s5"],"why_material":"The historical warning remains economically current.","evidence_status":"specified + externally attested"},{"id":"c7","text":"Putting caches.default before KV bounds refresh writes by cache expiry rather than request traffic.","section":"Bounding writes by putting the edge cache in front of KV","tier":"system","source_ids":["p5","s6"],"why_material":"It converts an unbounded traffic-driven bill into a deliberate freshness tradeoff.","evidence_status":"specified + externally attested"},{"id":"c8","text":"KV limits keys to 512 bytes, values to 25 MiB, metadata to 1024 bytes and same-key writes to one per second.","section":"The per-key boundaries, and the error you get at each one","tier":"fact","source_ids":["s4"],"why_material":"These are schema and traffic boundaries, not tuning suggestions.","evidence_status":"specified"},{"id":"c9","text":"A merged vinext repair preserves short cache keys and hashes the overflow after reserving prefix space to avoid KV 414 failures.","section":"The per-key boundaries, and the error you get at each one","tier":"repository","source_ids":["s9"],"why_material":"It is a concrete repair for a production key-shape failure.","evidence_status":"implemented"},{"id":"c10","text":"KV get then put cannot implement a correct contended lock; D1 INSERT OR IGNORE or a Durable Object can.","section":"An eventually-consistent store cannot hold a lock, and this application's locks are only safe because nobody is racing","tier":"system","source_ids":["r4","s3"],"why_material":"Silent double ownership is worse than an explicit lock failure.","evidence_status":"observed + specified"},{"id":"c11","text":"The durable topology is transactional authority first, one propagation stream second and KV as the replicated read copy.","section":"The topology teams settle on: authority elsewhere, KV as the replicated read copy","tier":"system","source_ids":["p3","p6","s7"],"why_material":"It gives KV one writer per key and keeps reconciliation against an authoritative store.","evidence_status":"specified + externally attested"},{"id":"c12","text":"An operator uses KV for replicated project flags while keeping everything else in D1.","section":"The topology teams settle on: authority elsewhere, KV as the replicated read copy","tier":"anecdotal","source_ids":["p6"],"why_material":"It is a positive report aligned with KV's consistency model.","evidence_status":"externally attested"},{"id":"c13","text":"Another operator describes the latency tradeoff between eventual KV reads and waiting for an external authoritative database.","section":"The topology teams settle on: authority elsewhere, KV as the replicated read copy","tier":"anecdotal","source_ids":["p4"],"why_material":"It explains why teams misuse KV despite understanding the consistency cost.","evidence_status":"externally attested"},{"id":"c14","text":"A cache-fronted share-link design bounds each key to at most 24 cache misses per day with a one-hour max-age.","section":"Bounding writes by putting the edge cache in front of KV","tier":"anecdotal","source_ids":["p5"],"why_material":"It is a positive operator pattern with explicit economics and staleness.","evidence_status":"externally attested"},{"id":"c15","text":"The seven-day account measurement recorded 899,100 reads, 85,620 writes, 740 deletes and 160 lists.","section":"Measured on this account today","tier":"measurement","source_ids":["r2"],"why_material":"It supplies the actual operation mix behind the cost calculation.","evidence_status":"observed"},{"id":"c16","text":"In the measured week, writes were 8.7% of operations but 48.5% of gross list-rate cost.","section":"Measured on this account today","tier":"calculation","source_ids":["r2","s5"],"why_material":"It shows why write control matters before total traffic looks large.","evidence_status":"observed + specified"},{"id":"c17","text":"Two same-area visibility trials converged in 0.21 and 0.30 seconds, but neither establishes read-after-write consistency.","section":"Measured on this account today","tier":"measurement","source_ids":["r3","s1"],"why_material":"Observed speed is separated from the documented guarantee.","evidence_status":"observed + specified"},{"id":"c18","text":"The independent IAD benchmark used 150 samples per metric and measured KV hot reads at 2.6 ms p50 and writes at 171.8 ms p50.","section":"Measured on this account today","tier":"independent","source_ids":["s11"],"why_material":"A disclosed competitor harness still captures the read-fast/write-slow asymmetry.","evidence_status":"observed"},{"id":"c19","text":"Cloudflare reports that its hottest 0.03% of keys serve over 40% of global KV requests and resolve in under one millisecond.","section":"Measured on this account today","tier":"publisher_claim","source_ids":["s8"],"why_material":"It explains why hot edge reads can be exceptionally fast.","evidence_status":"specified"},{"id":"c20","text":"The fresh namespace list found 6,767 keys, including 6,568 regenerable lastgood snapshots.","section":"The next read-only inventory still shows snapshots dominating the namespace","tier":"measurement","source_ids":["r1"],"why_material":"The live key mix matches the recommended read-copy role.","evidence_status":"observed"},{"id":"c21","text":"The longest live key name is 110 bytes, below the 512-byte hard limit.","section":"The next read-only inventory still shows snapshots dominating the namespace","tier":"measurement","source_ids":["r1","s4"],"why_material":"It verifies current headroom against a known failure boundary.","evidence_status":"observed + specified"},{"id":"c22","text":"Fresh list metadata covers 1,046 values totaling 175,859,336 recorded bytes; the largest is 2,140,072 bytes.","section":"The next read-only inventory still shows snapshots dominating the namespace","tier":"measurement","source_ids":["r5"],"why_material":"It measures snapshot storage without fetching bodies.","evidence_status":"observed"},{"id":"c23","text":"Cloudflare's own documentation repository records explicit clarifications to the KV consistency contract.","section":"Eventual consistency, in the exact words of the reference","tier":"repository","source_ids":["s10"],"why_material":"The public source history makes the contract auditable.","evidence_status":"implemented"}],"sources":[{"id":"s1","type":"specification","url":"https://developers.cloudflare.com/kv/concepts/how-kv-works/","title":"How Workers KV works","quote":"Negative lookups indicating that the key does not exist are also cached, so the same delay exists noticing a value is created as when a value is changed.","summary":"Normative consistency model: central storage, regional caches, stale values and cached misses.","publisher":"Cloudflare","claim_ids":["c1","c17","c2"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"genesis","hash":"25a663bdc376c779923fc6158fd7c65c5a0330f9dfe455a4f62dd4295c4cc55f"},{"id":"s2","type":"specification","url":"https://developers.cloudflare.com/kv/api/read-key-value-pairs/","title":"Read key-value pairs","quote":"get() and getWithMetadata() methods may return stale values.","summary":"Workers Binding API for reads, metadata and cacheTtl, including the stale-read warning.","publisher":"Cloudflare","claim_ids":["c2"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"25a663bdc376c779923fc6158fd7c65c5a0330f9dfe455a4f62dd4295c4cc55f","hash":"bb2f0147961457bb720e1909a6859cfa58ca16927ceb54b0cc15b3e49382388a"},{"id":"s3","type":"specification","url":"https://developers.cloudflare.com/kv/api/write-key-value-pairs/","title":"Write key-value pairs","quote":"Due to the eventually consistent nature of KV, concurrent writes to the same key can end up overwriting one another.","summary":"Workers Binding API for put, metadata and expiry, including the concurrent-write warning.","publisher":"Cloudflare","claim_ids":["c10","c3"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"bb2f0147961457bb720e1909a6859cfa58ca16927ceb54b0cc15b3e49382388a","hash":"c43a365f1fdff1dc9df212c2d6be72787619ff5aa5787a0f8be900f384ea5a17"},{"id":"s4","type":"publisher_documentation","url":"https://developers.cloudflare.com/kv/platform/limits/","title":"Workers KV limits","quote":"Writes to same key","summary":"Hard per-key, per-value, metadata, namespace and invocation limits.","publisher":"Cloudflare","claim_ids":["c21","c8"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"c43a365f1fdff1dc9df212c2d6be72787619ff5aa5787a0f8be900f384ea5a17","hash":"124486035d659fc7ad02c66f3a714dc20efe2c93f19c512758c79b36b42589b8"},{"id":"s5","type":"publisher_documentation","url":"https://developers.cloudflare.com/kv/platform/pricing/","title":"Workers KV pricing","quote":"All operations incur charges, including fetches for non-existent keys that return a null (Workers API) or HTTP 404 (REST API).","summary":"Current read, write, delete, list and stored-data allowances and overage rates.","publisher":"Cloudflare","claim_ids":["c16","c4","c5","c6"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"124486035d659fc7ad02c66f3a714dc20efe2c93f19c512758c79b36b42589b8","hash":"cf304f6de8d11281754680e5926e7c0f099a6bc15e038afb207260c65092c523"},{"id":"s6","type":"publisher_documentation","url":"https://developers.cloudflare.com/workers/runtime-apis/cache/","title":"Workers Cache API","quote":"The Cache API is a programmatic interface for reading from and writing to Cloudflare's cache from inside a Worker.","summary":"Free per-location cache primitive used to absorb repeat reads before KV.","publisher":"Cloudflare","claim_ids":["c7"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"cf304f6de8d11281754680e5926e7c0f099a6bc15e038afb207260c65092c523","hash":"d28a8dcfd8fa323d1b306709e38970dcbbc775d051e97c1ca78874dade47c655"},{"id":"s7","type":"publisher_documentation","url":"https://developers.cloudflare.com/workers/platform/storage-options/","title":"Workers storage options","quote":"This guide describes the storage & database products available as part of Cloudflare Workers, including recommended use-cases and best practices.","summary":"Official comparison surface for KV, D1, Durable Objects, R2 and external databases.","publisher":"Cloudflare","claim_ids":["c11"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"d28a8dcfd8fa323d1b306709e38970dcbbc775d051e97c1ca78874dade47c655","hash":"747ec212aaf55769a366b77bd1d2bae1e4cd56bb81389a7c1343072e88133b44"},{"id":"s8","type":"publisher_documentation","url":"https://blog.cloudflare.com/faster-workers-kv/","title":"Cloudflare's Workers KV latency measurements","quote":"KV reads for these keys, which represent over 40% of Workers KV requests globally, resolve in under a millisecond.","summary":"Vendor measurement of the tiered cache architecture and hot-key latency distribution.","publisher":"Cloudflare","date":"2024-09-26","claim_ids":["c19"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"747ec212aaf55769a366b77bd1d2bae1e4cd56bb81389a7c1343072e88133b44","hash":"e2619fd67cada3f4e1be8bbe3a79151e07934b584ac919808c1d63a18f95f30b"},{"id":"s9","type":"repository","url":"https://github.com/cloudflare/vinext/pull/2606","title":"vinext fix for KV's 512-byte cache-key limit","quote":"When the assembled key exceeds Cloudflare KV's 512-byte key limit, `handler.get` throws a 414 **before** the wrapped function runs","summary":"Merged code repair: retain short keys and hash only overflow after reserving prefix space.","author":"blitss","publisher":"GitHub","date":"2026-07-13","claim_ids":["c9"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"e2619fd67cada3f4e1be8bbe3a79151e07934b584ac919808c1d63a18f95f30b","hash":"56f18f5cf6a2ed0ccab15b64cee7150cbbd8edbcda19de4bab11e372d20bb4d5"},{"id":"s10","type":"repository","url":"https://github.com/cloudflare/cloudflare-docs/pull/2678","title":"Cloudflare documentation clarification for KV consistency","quote":"Add KV clarifications","summary":"Public documentation change where stale reads, concurrent overwrites and cache behavior are visible in the source history.","publisher":"GitHub","date":"2021-11-11","claim_ids":["c23"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"56f18f5cf6a2ed0ccab15b64cee7150cbbd8edbcda19de4bab11e372d20bb4d5","hash":"b41d1481d70c92ba75a71d83dcd1ab40fcf19e66c6cdd388d438972d05a35eb0"},{"id":"s11","type":"independent_measurement","url":"https://upstash.com/blog/upstash-redis-vs-cloudflare-kv","title":"Upstash Redis versus Cloudflare KV benchmark","quote":"I deployed a Cloudflare Worker that calls KV through the binding and Upstash through the official @upstash/redis/cloudflare client (HTTPS REST), then ran four scenarios: 5 runs × 30 samples = 150 samples per metric, all served from Cloudflare's Washington DC data center (IAD).","summary":"Competitor-authored but reproducible harness: 150 samples per metric from one Worker and one location, with KV binding and Upstash HTTPS held side by side.","author":"Josh","publisher":"Upstash","date":"2026-05-27","claim_ids":["c18"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"b41d1481d70c92ba75a71d83dcd1ab40fcf19e66c6cdd388d438972d05a35eb0","hash":"450ab2c6b14a727ea1637c26dd3b64ef51b25a4fbd8d80f0b94e3434b9707ae6"},{"id":"p1","type":"hn","url":"https://news.ycombinator.com/item?id=48672342","title":"OAuth for all","quote":"KV is not a distributed database and is really not intended as a database alternative at all. It's more meant for distributing bits of config globally. Cost aside, writes are way too slow for database-ish use","summary":"The Workers tech lead telling a user who had adopted KV as a datastore that this is a misuse: writes are too slow and eventual consistency is wrong for frequently-changing state, and to use Durable Objects SQLite or Hyperdrive instead. Negative on the common KV-as-database pattern.","author":"kentonv","publisher":"Hacker News","date":"2026-06-25","claim_ids":["c1"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"450ab2c6b14a727ea1637c26dd3b64ef51b25a4fbd8d80f0b94e3434b9707ae6","hash":"c4bf1f054fc164522d3a721b6cf6d6b6af2482b5c49b6d6858fa3040495c48ec"},{"id":"p2","type":"hn","url":"https://news.ycombinator.com/item?id=28703233","title":"A bit of math around Cloudflare's R2 pricing model","quote":"Workers KV is also eventually-consistent with no guarantee of read-after-write, which is a pretty big limitation compared to alternatives (S3 even has immediately-consistent list operations now after write).","summary":"Cost and consistency breakdown: KV at $5/million writes and $0.50/million reads (pricier per read than S3), plus no read-after-write guarantee. Contrasts with Durable Objects storage at $1/million 4KB writes but with the DO runtime cost stacked on top. Negative.","author":"kondro","publisher":"Hacker News","date":"2021-09-30","claim_ids":["c4","c6"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"c4bf1f054fc164522d3a721b6cf6d6b6af2482b5c49b6d6858fa3040495c48ec","hash":"b0ae1f09af39d9b55b1a6b47f028c4753de7f3b91b508e0e8861a72c773ed75f"},{"id":"p3","type":"hn","url":"https://news.ycombinator.com/item?id=22644115","title":"Launch HN: Fly.io (YC W20) – Deploy app servers close to your users","quote":"Cloudflare Workers KV has the simplest model, with a central-db that transparently and eventually only replicates read-only, hot-data specific to a DC but writes continue to incur heavy penalty","summary":"Describes their actual production topology: DynamoDB as single-region source of truth, DynamoDB Streams pushing into Workers KV, reads served from KV at the edge. They deliberately keep writes off KV because of ops-per-second, cost and latency penalties, and to avoid lock-in. Mixed, leaning negative on KV writes.","author":"ignoramous","publisher":"Hacker News","date":"2020-03-21","claim_ids":["c11"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"b0ae1f09af39d9b55b1a6b47f028c4753de7f3b91b508e0e8861a72c773ed75f","hash":"7f95c19d457b58f3149a9083cfe1f4856c471b0d710f424cbc573bec36a703fa"},{"id":"p4","type":"hn","url":"https://news.ycombinator.com/item?id=28581040","title":"Reality Check for Cloudflare Wasm Workers and Rust","quote":"You can use KV, with its trade-off of eventual consistency, or use something like FaunaDB or Firebase, but that means that the request has to wait for the request to the backing service.","summary":"Frames the practical bind: Workers have no durable disk and no region control, so you either accept KV's eventual consistency or pay a round trip to an external database. Also finds Workers Unbound pricing opaque. Negative.","author":"DenseComet","publisher":"Hacker News","date":"2021-09-19","claim_ids":["c13"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"7f95c19d457b58f3149a9083cfe1f4856c471b0d710f424cbc573bec36a703fa","hash":"78ad489e86c3ad90c0059f457ef3c7606bd96641ed372ec9b9532609cf66302b"},{"id":"p5","type":"hn","url":"https://news.ycombinator.com/item?id=47917107","title":"Durable Object alarm loop: $34k in 8 days, zero users, no platform warning","quote":"The key property is that caches.default with Cache-Control: max-age=3600 becomes a natural throttle — at most 24 cache misses per day per key, so KV writes are bounded by (keys × 24) regardless of traffic.","summary":"Describes a running share-link backend that uses KV plus the edge cache with a sliding TTL specifically to bound KV write cost, instead of DO + alarms. Accepts loss of strong consistency in exchange for writes that cannot run away. Positive pattern, written in response to a runaway-cost postmortem.","author":"jacobmei","publisher":"Hacker News","date":"2026-04-27","claim_ids":["c14","c7"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"78ad489e86c3ad90c0059f457ef3c7606bd96641ed372ec9b9532609cf66302b","hash":"65e7428e4eb02639b7319f57bae36b11cbef8b9d2c2877105f8d59bab1cee439"},{"id":"p6","type":"hn","url":"https://news.ycombinator.com/item?id=42531229","title":"Show HN: An edge first feature flag implementation on Cloudflare","quote":"I mostly use KV for storing flags specific to each project (which gets replicated automatically). Everything else goes to D1 (replication isn't needed here).","summary":"Author of an edge feature-flag system: flags live in KV for its built-in geo replication, configuration lives in D1. Elsewhere in the thread he notes KV still has propagation delay on updates. Positive use of KV for exactly the flags/config case.","author":"dj0k3r","publisher":"Hacker News","date":"2024-12-28","claim_ids":["c11","c12"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"65e7428e4eb02639b7319f57bae36b11cbef8b9d2c2877105f8d59bab1cee439","hash":"e3d074248824ff45c22c316ff194fa3294248a3210c0e1fbf02cc7611770c3e1"},{"id":"r1","type":"runtime_receipt","url":"https://miscsubjects.com/api/articles/cloudflare-os-kv","title":"Fresh first-party KV namespace inventory","quote":"Keys in the production namespace | 6,767","summary":"Wrangler key-list inventory counted keys, prefixes, name bytes and metadata without reading values or mutating the namespace.","publisher":"miscsubjects.com","date":"2026-07-26","claim_ids":["c20","c21"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"e3d074248824ff45c22c316ff194fa3294248a3210c0e1fbf02cc7611770c3e1","hash":"550da79f541bf7d9a649e268837e7d93270d62abdbd5420fcf22e5dd5f39f47d"},{"id":"r2","type":"runtime_receipt","url":"https://miscsubjects.com/api/articles/cloudflare-os-kv","title":"First-party seven-day KV operations receipt","quote":"Seven days of real operations — 899,100 reads, 85,620 writes, 740 deletes, 160 lists.","summary":"Cloudflare GraphQL kvOperationsAdaptiveGroups measurement for 2026-07-19 through 2026-07-26, with the query published.","publisher":"miscsubjects.com","date":"2026-07-26","claim_ids":["c15","c16"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"550da79f541bf7d9a649e268837e7d93270d62abdbd5420fcf22e5dd5f39f47d","hash":"26895d8e05017d4f90575d88122693083aad415cd1eb4526f27b8ad8f21e6a73"},{"id":"r3","type":"runtime_receipt","url":"https://miscsubjects.com/api/articles/cloudflare-os-kv","title":"First-party KV visibility probe","quote":"visible in 0.21 s and 0.30 s across two trials.","summary":"Two temporary-key trials, one after six cached 404s; both keys deleted and verified gone. Explicitly not evidence of a consistency guarantee.","publisher":"miscsubjects.com","date":"2026-07-25","claim_ids":["c17"],"accessed_at":"2026-07-26T05:45:59.424Z","prev":"26895d8e05017d4f90575d88122693083aad415cd1eb4526f27b8ad8f21e6a73","hash":"bfcd1eac2af2e6fd532c4cd026093459cd8cd774b94f1e16e6e2f2df95ca3dc3"},{"id":"r4","type":"runtime_receipt","url":"https://miscsubjects.com/api/articles/cloudflare-os-kv","title":"First-party KV-lock code audit","quote":"KV get→fire→put races: parallel identical calls all miss, all fire.","summary":"Local code inspection contrasts advisory KV leases with D1 INSERT OR IGNORE for contended idempotency 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'{\"slug\":\"cloudflare-os-kv\",\"sources\":[{\"type\":\"review\",\"url\":\"<url>\",\"title\":\"<title>\",\"quote\":\"<verbatim quote>\",\"summary\":\"<one line>\"}]}'","objection":"curl -s -X POST https://miscsubjects.com/api/articles/cloudflare-os-kv/objections -H 'content-type: application/json' -d '{\"actor\":\"<model>\",\"objection\":\"<attack>\",\"surface\":\"S1-S8\",\"minimum_patch\":\"<patch>\"}'  # open intake, no key","thread_update":"curl -s -X POST https://miscsubjects.com/api/protocol/thread-update -H 'content-type: application/json' -d '{\"actor\":\"<model>\",\"target\":\"cloudflare-os-kv\",\"raw_text\":\"<material delta>\"}'  # open intake, no key","read_back":"curl -s https://miscsubjects.com/api/articles/cloudflare-os-kv | python3 -c 'import json,sys; d=json.load(sys.stdin); print(json.dumps(d[\"claims\"][-3:], 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