[WRONG BRANCH] fix(cursor): catch EOF terminal budget overflow

[luvs01]

Motivation

• A synthesized terminal on clean Cursor EOF could call push() outside the existing guarded frame-processing path, and push() can synchronously throw TranslatorBudgetExceededError, which previously produced an unhandled rejection and left the turn unsettled.

Description

• Change the EOF drain promise chain to route any exception raised while synthesizing terminal events into the existing failure path by replacing the .then(..., onRejected) tail with a .then(...).catch(...) that calls failAndClear in src/adapters/cursor/live-transport.ts.
• Add a focused regression test in tests/cursor-hardening.test.ts that constrains the translator budget, simulates many small assistant text frames followed by a clean EOF, and asserts a typed TranslatorBudgetExceededError is observed and that budget ownership is released.
• Keep the behavior of synthesizing typed truncation finalizeTurnEvents() unchanged while ensuring any transport-budget overflows during synthesis settle the turn consistently.

Testing

• Ran focused typecheck with bun run typecheck which succeeded.
• Ran the Cursor hardening tests with bun test tests/cursor-hardening.test.ts (Bun 1.3.14) and observed the new and existing Cursor tests pass (34 passed, 0 failed).
• Ran bun run privacy:scan which completed successfully, and attempted a full bun run test but the repository-wide suite hit unrelated integration timeouts/failures outside the changed area.

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Codex Task

Summary by CodeRabbit

• Bug Fixes

  • Improved handling of asynchronous errors when a live connection ends.
  • Ensured repeated text frames correctly report translator budget exhaustion instead of ending silently.
  • Confirmed translator resources are fully released after the error.

• Tests

  • Added coverage for clean connection termination and translator budget limits.

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between e97fb26 and 6752130.

📒 Files selected for processing (2)

• src/adapters/cursor/live-transport.ts
• tests/cursor-hardening.test.ts

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📝 Walkthrough

Walkthrough

The live transport now catches asynchronous frame-drain failures through .catch(). A hardening test covers repeated text frames, clean Connect EOF, translator budget exhaustion, and complete buffer release.

Changes

Live transport hardening

Layer / File(s)	Summary
Transport failure cleanup and regression coverage src/adapters/cursor/live-transport.ts, tests/cursor-hardening.test.ts	At line 1078, asynchronous frame-drain failures now invoke failAndClear through .catch(). Lines 447–500 add coverage for repeated assistant text frames that exceed the 1,000-byte translator budget, assert TranslatorBudgetExceededError with translation_buffer_limit, and verify that zero buffered bytes remain.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to 67521

This localized change routes EOF terminal-synthesis budget errors into the existing failure path and adds focused regression coverage; no actionable merge-blocking risk remains at the current head.

Suggested reviewers: lidge-jun, wibias, yansigit

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the Cursor EOF error-handling fix for terminal translator budget overflow.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage 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.

✨ Finishing Touches

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• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/fix-cursor-eof-synthesis-vulnerability

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[github-actions]

⏳ DRAFT

• wrong target branch (main); retarget to dev.

What to do

• Retarget this PR to dev — all contributions go to dev.

Its title has been prefixed with [WRONG BRANCH].
This pull request was already a draft. Its draft status will be preserved after every issue above is resolved.