fix(server): stop retaining queued Codex diff snapshots

[ScottN-PV]

What Changed

Codex turn-diff text is dropped before the runtime's raw-notification queue. Ingestion keeps only checkpoint identity and time, and repeated signals for one thread and turn merge in the existing keyed worker.

A key stays active until its own lifecycle work finishes, so duplicates cannot pile up in the next queue. The diff worker is serial. A diff for another turn waits for that one item, not for the whole lifecycle queue.

The keyed worker gains an all-key drain so the ingestion service keeps its deterministic drain. Native and canonical schemas are unchanged. The native diff field stays as an empty string. The diff also adds doc comments to functions in the touched files. They change no behavior.

Why

Fixes #12883.

Provider diff ingestion records a placeholder checkpoint and never reads the snapshot text. With Git detection blocked, repeated snapshots kept unused strings in memory and queued one detection job each. One blocked update followed by 200 more produced 201 detection calls on the baseline. It now produces at most two.

Validation

• 137 tests passed across CodexSessionRuntime.test.ts and ProviderRuntimeIngestion.test.ts, plus three KeyedCoalescingWorker tests.
• A generated four-million-character diff fails the retention test on the baseline and passes with the fix. Canonical diff inputs lose both raw and unified payloads before the ingestion queues.
• With Git blocked, turn completion still proceeds, late diffs do not overwrite settled state or rewind the latest turn, and the burst stays merged.
• After the acknowledgment change, all 89 ingestion tests passed. A two-thread test advances the second diff while a later lifecycle event is blocked. Restoring the whole-queue wait makes it time out.
• Targeted lint, formatting, the server typecheck, and git diff --check pass. The typecheck emitted Effect suggestions only.

Limits: these are deterministic payload and queue tests on Windows, not a heap benchmark. No live provider or UI session was tested. No test covers a lifecycle backlog queued ahead of the active diff. Input-frame parsing, other queues, and durable file-change payloads are outside this change.

Checklist

• This PR is small and focused
• I explained what changed and why
• Before/after screenshots (not applicable: server queue handling)
• Animation/interaction video (not applicable: deterministic backend regression)

Model: gpt-6-astra (reasoning medium, user-confirmed). Harness: OpenAI Codex in T3 Code. Integration and version were not exposed. Codex did the investigation, implementation, tests, automated checks, and doc comments. The session that made the acknowledgment change did not expose its model or effort.

Model: claude-fable-5-1 (effort high). Harness: Claude Code CLI 2.1.283 and 2.1.284, invoked by Codex through PowerShell. Reviewed the doc comments and drafted this description.

Human involvement: selected the issue, authorized the implementation, and requested and authorized the acknowledgment change and its push. Requested the doc comments and their review, and reviewed and approved the first doc-comment update. No manual testing or code review is claimed.

Summary by CodeRabbit

Summary

• Performance
  • Large code-change notifications now omit diff content while retaining thread and turn information, reducing the data they carry.
  • Rapid updates for the same turn are coalesced, preserving the latest update and limiting repeated repository checks.
• Reliability
  • Diff updates can progress while unrelated lifecycle work is blocked.
  • Queue draining now waits for active and queued updates to finish.

[macroscopeapp]

Approvability

Verdict: Would Approve

Macroscope's review found this PR approvable — This is a focused server-side memory and queueing fix that discards unused diff text and coalesces repeated signals, with targeted regression coverage and no schema or sensitive-path changes. An unresolved Medium-severity finding separately flags that global draining may delay unrelated diffs and lose placeholder checkpoints, so that risk remains an external blocker to resolve.

Not approved because:

• 1 blocking correctness issue found at or above your repo's Minimum Blocking Severity

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📒 Files selected for processing (3)

• apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.test.ts
• apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.ts
• apps/server/src/provider/Layers/CodexSessionRuntime.ts

🚧 Files skipped from review as they are similar to previous changes (3)

• apps/server/src/provider/Layers/CodexSessionRuntime.ts
• apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.test.ts
• apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.ts

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📝 Walkthrough

Walkthrough

Codex diff notifications and provider diff signals now retain less diff data. Provider ingestion coalesces diff work by thread and turn and waits for lifecycle processing. The keyed coalescing worker adds a drain operation.

Changes

Diff Queue Handling

Layer / File(s)	Summary
Codex notification projection apps/server/src/provider/Layers/CodexSessionRuntime.ts, apps/server/src/provider/Layers/CodexSessionRuntime.test.ts	turn/diff/updated notifications retain threadId and turnId and set diff to an empty string. The test checks serialized payload size and confirms that the input diff remains unchanged.
Keyed worker drain packages/shared/src/KeyedCoalescingWorker.ts, packages/shared/src/KeyedCoalescingWorker.test.ts	The keyed coalescing worker adds drain, which waits for active and queued work across keys. A test checks draining during a burst across two keys.
Provider diff processing apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.ts, apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.test.ts	Provider diff signals retain routing metadata, and ingestion coalesces work by thread and turn. Repository detection waits for the corresponding lifecycle work to finish through a per-input completion signal.

Priority: ➖ Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Bug fix · Severity of issue fixed: Medium

Sequence Diagram(s)

sequenceDiagram
  participant detectProviderDiffRepository
  participant processInput
  participant recordProviderDiff
  detectProviderDiffRepository->>processInput: enqueue diff input with completion Deferred
  processInput->>recordProviderDiff: process diff
  recordProviderDiff-->>processInput: finish lifecycle processing
  processInput-->>detectProviderDiffRepository: complete Deferred

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Merge Risk: ⚪ Minimal · up to 8287c

This change reduces memory retained by queued Codex diff snapshots and coalesces repeated diff signals. No merge-blocking risk is evident from the supplied context.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The PR meets the coding requirements in [#12883]. makeCodexServerNotification replaces turn/diff/updated diff text with an empty string before runtime queueing. providerDiffSignal retains checkp…
Out of Scope Changes check	✅ Passed	The changes stay within [#12883]. Payload reduction removes unused diff text from runtime queues. Signal projection and keyed-worker changes coalesce repeated snapshots and preserve required lifecycle…
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 6 files.
Title check	✅ Passed	The title clearly and concisely describes the primary change: preventing queued Codex diff snapshots from being retained.
Description check	✅ Passed	The description includes the required What Changed and Why sections, explains the implementation and motivation, documents validation results and limitations, and addresses non-applicable UI checklist…

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Inline comments:
In `@apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.ts`:
- Line 2700: Replace the global `worker.drain` wait in the diff-processing flow
with an acknowledgement tied to the specific enqueued diff, and await that
acknowledgement before advancing. Ensure unrelated lifecycle events cannot delay
the diff’s processing or cause its checkpoint to be rejected after the turn
completes.

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• apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.test.ts
• apps/server/src/orchestration/Layers/ProviderRuntimeIngestion.ts
• apps/server/src/provider/Layers/CodexSessionRuntime.test.ts
• apps/server/src/provider/Layers/CodexSessionRuntime.ts
• packages/shared/src/KeyedCoalescingWorker.test.ts
• packages/shared/src/KeyedCoalescingWorker.ts

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