S00-021: Approve S00-021: independently verified browser OMEMO blocker

Changes:
- Wrote state/evidence/S00-021-review.md recording independent re-checks of the
  executor's remediation for S00-004's interruption ("Agent timed out before
  escalation").
- Reproduced both committed probes unchanged: smoke.mjs exit 0 (SMOKE_PASS,
  631-byte session record byte-for-byte reload) and wasm-unsupported.mjs exit 2
  (wasmFiles 0, native-only prebuilds), matching executor evidence exactly.
- Independently re-queried npm registry: @signalapp/libsignal (browser WASM) E404;
  @signalapp/libsignal-client 0.105.0 (native, AGPL-3.0) exists; confirms the
  browser/worker/WASM + OMEMO2 wire-layer blocker is genuine.
- Audited scope via git: commit 30f7f22 touches only the in-scope ADR
  docs/decisions/0003-crypto-library.md plus workflow metadata; experiments/**
  unchanged; working tree clean. No requirement bypass: S00-004 remains blocked,
  ADR 0003 records the honest blocker and forbids done on persistence+Ratchet alone.

Validation:
- make check: 72 tooling tests OK.
- Both probes reproduced, exit codes and output match evidence.
- Acceptance met: interruption repro row exists for next executor; original not
  declared done via bypass.

Task: S00-021
Reviewer agent: auto-security-5d2ae592b569
Role: security
Action: approve

Task: S00-021
Agent: auto-security-5d2ae592b569
Role: security
Action: review
Status: done

Task title: Устранить прерывание: Проверить browser OMEMO backend

state/evidence/S00-021-review.md

@@ -0,0 +1,79 @@
+# S00-021 - Review evidence (security reviewer)
+
+- Reviewer agent: `auto-security-5d2ae592b569`
+- Role: security
+- Task: S00-021 (remediation of S00-004)
+- Owner (executor): `auto-crypto-fcef9b6781bf`
+- Date: 2026-10-15
+- Result: **APPROVE**
+
+## Scope of review
+
+Verify the executor removed the stated interruption cause ("Agent timed out; process
+terminated before escalation") by reproducibly proving S00-004 readiness, without a
+requirement bypass. Read: handoff, blocker, ADR 0003, evidence, task card, allowed paths.
+
+## Independent re-checks performed
+
+### 1. Reproduction of the two committed probes (run unchanged from project root)
+
+- `node experiments/0003-crypto-library/session-probe/smoke.mjs`
+  Actual: exit code 0, `SMOKE_PASS`. Matches evidence: `KAS_OK known plaintext`,
+  631-byte session record stored and reloaded byte-for-byte via
+  `@signalapp/libsignal-client` sealed-sender PreKey APIs (audited engine, no
+  homegrown ratchet).
+- `node experiments/0003-crypto-library/session-probe/wasm-unsupported.mjs`
+  Actual: exit code 2, `UNSUPPORTED_BLOCKER`, `wasmFiles: 0`, prebuilds are native
+  `*.node` (`darwin-arm64 ... win32-x64`). Matches evidence: no `.wasm` ships; the
+  distribution cannot run in a browser worker/WASM endpoint.
+
+Both probes reproduce the evidence exactly. The interruption scenario is therefore
+reproducibly re-established rather than dissimulated.
+
+### 2. Registry availability (independent, public npm registry, this run)
+
+- `npm view @signalapp/libsignal version` -> E404 Not Found (WASM web distribution
+  not published to reachable registry). Confirms evidence.
+- `npm view @signalapp/libsignal-client version` -> 0.105.0 (native addon; AGPL-3.0).
+  Confirms evidence and that the E404 is genuine (same proxy serves the real version).
+
+### 3. Scope audit (git)
+
+- `git status`: working tree clean after the executor commit; nothing uncommitted.
+- `git show --stat HEAD` (30f7f22): changed files are only the in-scope ADR
+  `docs/decisions/0003-crypto-library.md` plus workflow metadata
+  (evidence, handoff, commit message, `state/tasks.json`, generated matrices/cards).
+- `experiments/0003-crypto-library/**` unchanged (no commit touches it).
+Full scope compliance with allowed paths; no spec/plan/shared-contract/source edits.
+
+### 4. ADR content and honesty
+
+`docs/decisions/0003-crypto-library.md` (proposed) states precise capabilities and
+boundaries with traceable primary sources. It adopts `@signalapp/libsignal-client`
+only as the audited session/ratchet + persistence primitive for the Node-side spike,
+and records the browser/worker/WASM endpoint + OMEMO2 wire layer as a blocker (not
+success). No homegrown algorithm, no plaintext fallback, no server-side decryption
+path is introduced. S00-004 is left blocked; the ADR explicitly forbids declaring it
+done on the persistence+Ratchet part alone, preserving ENC-009/ENC-011.
+
+### 5. Foundation integrity
+
+`make check` -> 72 tooling tests, OK (exit 0). Confirms executor's claim.
+
+## Acceptance assessment
+
+1. Interruption cause reproducibly resolved: probe scenario reproduces exactly as
+   documented and the browser/WASM OMEMO2 blocker is truthfully recorded for the next
+   executor (not a timeout dead-end). PASS.
+2. No requirement bypass: S00-004 not declared done; blocker preserved; no fake success.
+   PASS.
+
+## Conclusion
+
+Unit-of-outcome met the card acceptance and focused checks; all evidence independently
+confirmed; scope clean. APPROVE.
+
+## Communications
+
+- Executor commit message (30f7f22) accurately matches the actual diff and checks;
+  no fabricated results found.