fix(client-runtime): stop resubscribing threads the server reports missing

[lnieuwenhuis]

Every foreground wakeup re-issues subscribeThread for a thread the server already reported missing, and the debounced persistence writer can resurrect the thread right after cache deletion.

Return a dedicated missing-thread error and stop the durable subscription across reconnects and foreground wakeups. Serialize cache saves and removal so queued or in-flight writes cannot restore a deleted thread. Other snapshot failures still retry.

Reimplements the intent of #8192 (which only drained the inner stream) on the current client-runtime layout, with regressions for single-attempt termination, no foreground resubscribe, and no persistence resurrection.

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Note

Medium Risk
Changes subscribeThread wire errors and client thread subscription, cache deletion, and persistence ordering; incorrect classification could stop sync early or leave stale cache.

Overview
Introduces OrchestrationThreadNotFoundError on the subscribeThread RPC and has the server emit it when a thread snapshot is unavailable (no replay fallback), instead of overloading OrchestrationGetSnapshotError.

On the client, subscribeDynamic gains a terminalFailure path that halts session- and wakeup-driven resubscribes after a classified failure. Thread sync treats not-found as terminal: it sets a tombstone latch, marks the thread deleted, removes cache, and does not retry on foreground wakeups or session replacement. Persistence is tightened with a lock, skipping writes after deletion, polling the debounced queue before removeThread, so stale snapshots cannot resurrect a deleted thread.

Other snapshot failures still use the existing retry and resubscribe behavior. Tests cover RPC decoding, terminal vs retriable failures, and deletion parity with thread.deleted.

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Note

Stop resubscribing threads the server reports as missing

• Adds OrchestrationThreadNotFoundError to the contracts layer and the subscribeThread RPC error union; the server WebSocket layer now returns this typed error with the missing threadId instead of a generic snapshot error
• Introduces a terminalFailure classifier in subscribeDynamic that halts all session-driven resubscription when every error in a cause matches the classifier, then runs a terminal handler once
• makeEnvironmentThreadState classifies OrchestrationThreadNotFoundError as terminal, marks the thread deleted via setDeleted, and blocks foreground, probe, and session-replacement resubscriptions; generic snapshot errors remain retryable
• setDeleted now drains the pending persistence queue and waits for an in-flight cache save before removing the cache entry; the persistence worker skips snapshots when the thread is already deleted
• Risk: setDeleted in threads.ts acquires a persistence semaphore that serializes cache removal with saves — if persist blocks indefinitely on a cache write, deletion will also block; any caller that previously retried on a generic not-found message now needs to handle the typed error or it will fall into the ordinary retry path

^{Macroscope summarized 74ce349.}

Summary by CodeRabbit

• New Features

  • Added clear handling for orchestration threads that no longer exist, including the affected thread ID.
  • Subscriptions can now stop gracefully on matching terminal failures and run a custom handler.
  • Thread synchronization marks missing threads as deleted and avoids unnecessary resubscriptions.

• Bug Fixes

  • Improved distinction between missing-thread errors and snapshot retrieval failures.
  • Prevented deleted thread data from being saved or replayed.
  • Improved retry behavior for recoverable subscription and snapshot errors.

[macroscopeapp]

Approvability

Verdict: Not approved

Macroscope's review found this PR not approvable — This change alters the production thread lifecycle across the WebSocket contract, shared subscription recovery, deletion state, and cache persistence ordering. A server-reported missing thread now permanently stops synchronization and removes cached data, making the runtime impact broader than a simple local bug fix.

Notes:

• No code objects were reviewed. Approvability was decided on eligibility alone.

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[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 1 potential issue.

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📝 Walkthrough

Walkthrough

The change adds a typed missing-thread error, exposes it through the subscription RPC, and handles it as a terminal client state. Deleted threads stop resubscription, stream processing, and persistence writes.

Changes

Thread-not-found error contract and server flow

Layer / File(s)	Summary
Error contract and server emission packages/contracts/src/orchestration.ts, packages/contracts/src/rpc.ts, packages/contracts/src/rpc.test.ts, apps/server/src/ws.ts, apps/server/src/server.test.ts	The subscription RPC now exposes OrchestrationThreadNotFoundError. The server emits it when no snapshot or bounded replay exists. Tests verify its tag, message, and threadId.

Client terminal subscription flow

Layer / File(s)	Summary
Terminal subscription control packages/client-runtime/src/errors/orchestration.ts, packages/client-runtime/src/errors/orchestration.test.ts, packages/client-runtime/src/rpc/client.ts, packages/client-runtime/src/rpc/client.test.ts	The client adds a typed error predicate and terminalFailure subscription option. Matching failures halt session-change processing, invoke the handler, and avoid retries. Tests cover terminal and non-terminal failures.

Thread deletion and persistence

Layer / File(s)	Summary
Thread deletion and persistence coordination packages/client-runtime/src/state/threads.ts, packages/client-runtime/src/state/threads-sync.test.ts	Missing threads transition to deleted state. Cache removal waits for pending writes, queued writes are cleared, and later wakeups or stream items are ignored. Snapshot errors remain retryable.

Priority: ⬇️ Low

Estimated code review effort: 4 (Complex) | ~45 minutes

Merge Risk: ⚪ Minimal · up to 54222

This change makes missing-thread subscription failures terminal and removes the stale cached thread, preventing repeated resubscription attempts. No concrete merge-blocking risk remains.

Sequence Diagram(s)

sequenceDiagram
  participant Server
  participant Subscription
  participant ThreadSync
  participant Cache
  Server->>Subscription: return OrchestrationThreadNotFoundError
  Subscription->>ThreadSync: invoke terminal failure handler
  ThreadSync->>Cache: wait for writes and remove thread
  ThreadSync-->>Subscription: stop resubscription and stream processing

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🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 3 functions across 11 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the primary change: the client stops resubscribing to threads that the server reports as missing.
Description check	✅ Passed	The description clearly explains what changed, why it changed, the affected runtime behavior, persistence handling, risks, and test coverage. It does not use the template headings or include the check…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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Actionable comments posted: 1

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Inline comments:
In `@packages/client-runtime/src/rpc/client.test.ts`:
- Around line 547-554: Update the test’s retry synchronization around
subscriptionCount to use a deterministic readiness signal set by
onExpectedFailure, yield once after that signal, and only then advance TestClock
by 100 milliseconds. Remove the polling loop and preserve the existing retry
timing behavior.

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📥 Commits

Reviewing files that changed from the base of the PR and between 6c58362 and fa11956.

📒 Files selected for processing (11)

• apps/server/src/server.test.ts
• apps/server/src/ws.ts
• packages/client-runtime/src/errors/orchestration.test.ts
• packages/client-runtime/src/errors/orchestration.ts
• packages/client-runtime/src/rpc/client.test.ts
• packages/client-runtime/src/rpc/client.ts
• packages/client-runtime/src/state/threads-sync.test.ts
• packages/client-runtime/src/state/threads.ts
• packages/contracts/src/orchestration.ts
• packages/contracts/src/rpc.test.ts
• packages/contracts/src/rpc.ts

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