@@ -73,6 +73,7 @@ Change them in the plan that decides them, not downstream.
   --use-env-proxy --disable-warning=MODULE_TYPELESS_PACKAGE_JSON`.
 - Environment contract (PR 33/34): `QUARTO_NODE`, `QUARTO_NODE_OPTIONS`, `QUARTO_NODE_VERSION`; `NODE_OPTIONS`/`NODE_PATH` are saved into `QUARTO_SAVED_*` for Quarto's own process and restored for children; `QUARTO_DENO*` are ignored or translated with a one-time warning and `QUARTO_DENO` is never aliased to the Node binary; `QUARTO_RUN_RUNTIME=deno` or the project key `script-runtime` selects the Deno tool for `.ts` scripts (PR 35); `QUARTO_RUN_DENO_NOTICE=0` silences the notice (PR 00c, 35).
 - Store names: project cache `index`, Sass cache `sass-index`; the backend picks the file (`<name>.kv` for PR 18's `Deno.openKv` backend, which Quarto 1.11 ships; `<name>.json` for PR 30's JSON backend, the only one on both runtimes from PR 30 on) so Quarto versions on different backends never share a file (PRs 18, 30).
+  Until PR 30, Deno KV stores also stay per V8 release branch, in a `v8-<v8Branch>` directory (`src/deno_ral/platform.ts`, #15180), because a Deno with a newer V8 writes values an older one cannot read.
 - `src/deno_ral/` keeps its name.
   `src/core/puppeteer.ts` keeps its name.
 - Ratchet exclusions for the `src` scope (`kSrcExclusions`, PR 02): `src/deno_ral/`, `src/vendor/`, `src/resources/extension-subtrees/`, `src/resources/scripts/`, `src/resources/create/`, `src/webui/quarto-preview/build.ts` (allow-listed until PR 33).
@@ -128,6 +129,10 @@ The rows below are the ones that still need a named person or an external answer
 | PRs 06 and 07 Decision 1 | the optional renames (`@cliffy/command` import style, `src/core/puppeteer.ts`) | coordinator | after PR 26 and after Phase 1 respectively; dropped if nobody asks |
 | PR 33 and PR 35 size | whether PR 33 lands as one PR or as 33a (Tasks 1, 11, 12, 16) + 33b (the flip), and PR 35 as one PR or 35a (Task 1 builder) + 35b (scripts) | maintainer | before Phase 3 starts |
 | User breakage after the flip | issue label, weekly triage owner during the soak, criterion to extend the dual-runtime window or the shim | release manager | before the first 1.12 prerelease |
+| PR 18, all tasks (from #15180) | the Deno backend keeps the `v8-<v8Branch>` store directory; reconcile it with the store names `index`/`sass-index` and the `<identifierHash>-<inputHash>.css` naming. Task 2 Step 2 shrinks to the API change: `this.index.list({ prefix: [] })` becomes `this.index.list([])`, and the `clear()` body #15180 shipped stays as is (`storeDir` paths, `safeRemoveSync`, immediate entries skipped; test `projectCache - clear() removes disk and immediate entries of a populated cache`). Drop the Context sentence saying `join` throws in `clear()`, and the Risks lines about that throwing path; one `cache.ts` `Deno.removeSync` is now `safeRemoveSync`. Refresh every Verified usage line number | coordinator | PR 18 step 0 |
+| PR 18 Tasks 1–3 (from the #15119 fix, once `src/deno_ral/kv.ts` is on `main`) | `kv.ts` already exists (`openKv`, `getKv`, `kvOp`, `KvDamagedError`) and both caches go through it, so Task 1 extends the file instead of creating it and its "Module not found" RED step no longer holds. `openKeyValueStore` keeps the damage mapping: a damaged value reads as a miss with one warning, a damaged file fails with `KvDamagedError` naming the folder to delete, any other error is wrapped with the path. The `src` baseline drops by 5, not 7 (the two `Deno.openKv` calls are already in the layer). The `Deno.openKv` grep acceptance check covers `src` and `package` only, since three cache tests build damaged fixtures with `Deno.openKv` on purpose. The `kv.ts` row in `.claude/rules/typescript/deno-ral.md` exists: update it | coordinator | PR 18 step 0 |
+| PR 19 Task 1, PR 27b | both replace the whole body of `platform.ts`: keep the `v8Branch` export (`_TEMPLATE.md`, "`platform.ts`"); PR 27b computes it from `process.versions.v8` | coordinator | step 0 of each |
+| PR 30 | tagged `v8-<branch>/` directories are left behind like the untagged `.kv` files; remove `v8Branch` and its contract-test line together with its last consumer. What "damaged" means for the JSON index (unparsable or truncated file): keep the miss-with-warning versus fail-naming-the-folder split or not. The Deno KV damage tests (`tests/unit/kv-damage.test.ts` and the damaged-store cases in `sass-cache.test.ts` and `project-cache.test.ts`, from the #15119 fix) build real SQLite damage: they are replaced or deleted here, because PR 32 runs the full unit suite on Node, where neither `Deno.openKv` nor its damage exists, and "`sass-cache.test.ts` stays green" is restated accordingly | maintainer (damage semantics), coordinator (the rest) | PR 30 step 0 |
 
 ## Shared rules and tables
 
 
@@ -282,14 +282,15 @@ export interface KeyValueStore {
   list<T>(prefix: KvKey): AsyncIterable<KvEntry<T>>;
   close(): void;
 }
-export function openKeyValueStore(dir: string, name: string): Promise<KeyValueStore>; // the backend chooses the file: `<dir>/<name>.kv` for PR 18's Deno.openKv backend (Quarto <= 1.11), `<dir>/<name>.json` for PR 30's JSON backend, the only one on both runtimes from PR 30 on; Quarto versions on different backends never share a file. Writes take the owned lock directory `<name>.json.lock` (PR 30, Interfaces, "Lock ownership": owner marker, liveness probe, guarded release; PR 33's build lock copies the rule)
+export function openKeyValueStore(dir: string, name: string): Promise<KeyValueStore>; // the backend chooses the file: `<dir>/<name>.kv` for PR 18's Deno.openKv backend (Quarto <= 1.11), `<dir>/<name>.json` for PR 30's JSON backend, the only one on both runtimes from PR 30 on; Quarto versions on different backends never share a file. The Deno backend also keeps each store per V8 release branch (`v8-<v8Branch>` directory, `platform.ts`, #15180), since Deno KV files written by a newer V8 cannot be read by an older one; the JSON backend needs no tag. Writes take the owned lock directory `<name>.json.lock` (PR 30, Interfaces, "Lock ownership": owner marker, liveness probe, guarded release; PR 33's build lock copies the rule)
 // Contract (PR 18 tests): a second handle on the same store sees a committed `set`; two processes writing different keys both persist (Node: lock + read-modify-rename).
 ```
 
 ### `platform.ts` (extended in PR 19)
 
 ```ts
 export const isWindows: boolean; export const isMac: boolean; export const isLinux: boolean; export const os: string; export const arch: string; // existing
+export const v8Branch: string; // existing (#15180): V8 release branch "<major>.<minor>"; Deno KV stores live under `v8-<v8Branch>/` because the V8 serializer format changes between branches. Every plan that rewrites platform.ts keeps it (PR 27b: from `process.versions.v8`); PR 30 removes it with its last consumer
 export function runtime(): { name: "deno" | "node" | "bun"; version: string }; // real detection from PR 19: Deno when `typeof Deno !== "undefined" && "version" in Deno`, Bun when `process.versions.bun`, else Node
 export function consoleColumns(): number | undefined;
 export function inspect(value: unknown, options?: { depth?: number; colors?: boolean }): string;