[WRONG BRANCH] fix(cursor): preserve malformed buffered tool args

[luvs01]

Motivation

• Cursor previously buffered incremental argsTextDelta and, when a completion arrived with no structured map, treated an incomplete JSON buffer as empty arguments, which the bridge serialized as {} and caused malformed/truncated arguments to be silently accepted downstream instead of failing-closed.

Description

• Change resolveCompletedArgs to preserve the buffered argsTextDelta when it is non-empty but not complete JSON, so malformed/truncated argument blobs are forwarded instead of being conflated with a genuinely no-arg call.
• Update the inline documentation to explain the new fail-closed intent for malformed buffered text.
• Add a focused regression test preserves incomplete streamed args when completion has no argument map in tests/cursor-protobuf-events.test.ts to verify the adapter emits the buffered truncated text at completion.
• Files modified: src/adapters/cursor/protobuf-events.ts, tests/cursor-protobuf-events.test.ts.

Testing

• Ran bun test tests/cursor-protobuf-events.test.ts, which passed (34 passed, 0 failed).
• Ran bun run typecheck (tsc --noEmit), which completed cleanly.
• Ran bun run privacy:scan, which passed.
• Ran git diff --check (no whitespace or diff issues found).

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Codex Task

Summary by CodeRabbit

• Bug Fixes

  • Preserved incomplete streamed tool-call arguments instead of replacing them with empty content.
  • Continued to normalize complete JSON arguments while keeping empty output only for calls without arguments.

• Tests

  • Added regression coverage for incomplete tool-call argument streams, including successful completion without errors.

[coderabbitai]

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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 1193075 and 0233e50.

📒 Files selected for processing (2)

• src/adapters/cursor/protobuf-events.ts
• tests/cursor-protobuf-events.test.ts

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📝 Walkthrough

Walkthrough

The change preserves incomplete streamed tool-call arguments when completion provides no structured argument map. A regression test verifies deferred start emission, the preserved argument delta, and the tool-call end event.

Changes

Cursor tool argument handling

Layer / File(s)	Summary
Preserve buffered arguments and cover incomplete streams src/adapters/cursor/protobuf-events.ts:338-346, tests/cursor-protobuf-events.test.ts:312-335	resolveCompletedArgs now retains malformed or incomplete buffered JSON instead of replacing it with an empty string. Complete JSON and structured argument maps keep their existing behavior. The regression test verifies the emitted start, partial argument text, and end events.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Mergeability Score: ⚪ Minimal · up to 0233e

This localized change preserves malformed buffered tool arguments instead of converting them to empty arguments, with focused tests and validation passing; no actionable merge-blocking risk remains.

Suggested reviewers: lidge-jun, wibias, ingwannu

🚥 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 and concisely describes the main change: preserving malformed buffered Cursor tool arguments.
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

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch codex/fix-empty-arguments-from-malformed-tool-calls

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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.

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Reject whitespace-only buffered arguments

When argsTextDelta contains only whitespace and completion has no argument map, returning the truthy buffer does not fail closed: toolCallArgumentsUsable trims it and accepts it as an empty no-arg call, while closeCurrentToolCall preserves the original whitespace instead of substituting {}. The response is therefore marked completed with arguments: " ", which is not valid JSON and can make the echoed call fail on the next turn. Reject whitespace-only non-empty buffers as malformed rather than forwarding them.

AGENTS.md reference: src/AGENTS.md:L19-L19

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