fix(ai): ignore a repeat TOOL_CALL_START for an already-tracked toolCallId

[citizen204]

Summary

ToolCallManager.addToolCallStartEvent keyed its internal map by index (event.index ?? map.size), but AG-UI's TOOL_CALL_START carries no index. A non-first-party or malformed producer sending a second START for a toolCallId already being tracked could either wipe accumulated TOOL_CALL_ARGS (same index — overwrites the slot, resetting arguments to '') or insert a duplicate row (missing/different index — getToolCalls() then returns the id twice and the engine runs the tool twice). First-party adapters emit START only once per call and are unaffected.

Fixes #1187

Changes

• packages/ai/src/activities/chat/tools/tool-calls.ts: addToolCallStartEvent now skips the event if a tool call with the same toolCallId is already tracked.
• packages/ai/tests/tool-call-manager.test.ts: two regression tests — a repeat START with the same explicit index (accumulated arguments must survive) and a repeat START with no index (must not duplicate the row).
• .changeset/tool-call-manager-repeat-start.md: patch changeset.

Ran vitest run tests/tool-call-manager.test.ts in packages/ai — 31 passed (29 existing + 2 new).

Summary by CodeRabbit

• Bug Fixes

  • Prevented repeated tool-call start events from creating duplicate calls.
  • Preserved accumulated tool-call arguments when duplicate start events are received.

• Tests

  • Added coverage for repeated tool-call events with and without an explicit index.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

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Run ID: eecbdd50-15dd-492d-a233-4a919dec2f9e

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Reviewing files that changed from the base of the PR and between 2eecfc8 and cf97e4a.

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• packages/ai/tests/tool-call-manager.test.ts

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📝 Walkthrough

Walkthrough

ToolCallManager now ignores repeated TOOL_CALL_START events for tracked tool-call IDs. Regression tests verify argument preservation and prevention of duplicate calls. A patch changeset documents the fix.

Changes

Repeated tool-call start handling

Layer / File(s)	Summary
Guard repeated starts and validate behavior packages/ai/src/activities/chat/tools/tool-calls.ts, packages/ai/tests/tool-call-manager.test.ts, .changeset/tool-call-manager-repeat-start.md	addToolCallStartEvent ignores tracked tool-call IDs. Tests cover repeated starts with and without an index. The changeset documents the patch.

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

Merge Risk: ⚪ Minimal · up to cf97e

The change ignores duplicate tool-call start events while preserving accumulated arguments and preventing duplicate execution; no actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: alemtuzlak, kolaworld

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the fix for repeated TOOL_CALL_START events on an already-tracked toolCallId.
Description check	✅ Passed	The description explains the problem, implementation, tests, changeset, and issue link, but omits the template checklist and release impact sections.
Linked Issues check	✅ Passed	The implementation skips repeated TOOL_CALL_START events and adds regression tests for argument loss and duplicate entries, satisfying issue #1187.
Out of Scope Changes check	✅ Passed	The code, tests, and changeset are directly related to preventing repeated TOOL_CALL_START events from corrupting tool-call tracking.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 2 files.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[nx-cloud]

View your CI Pipeline Execution ↗ for commit 8f93f0b

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☁️ Nx Cloud last updated this comment at 2026-08-22 21:37:26 UTC