docs(ai-chat): document stopping generation for custom agents

[ericallam]

Summary

Adds a "Stopping generation" section to the Custom agents page. It documents how stop works when you drop down from chat.agent to chat.createSession: pass turn.signal (a combined stop-and-cancel AbortSignal) to streamText, and turn.complete() cleans up the aborted partial, accumulates it as its own assistant message, and keeps the run alive for the next turn. turn.stopped distinguishes a user stop from a full run cancel.

Until now the createSession stop story only existed as scattered fields in the reference table; the client side (transport.stopGeneration) and the chat.agent run-callback signals were documented, but not the custom-agent turn loop. Steering for these backends is already covered on the pending messages page, which this page links to.

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Latest commit: 26a7c14

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[coderabbitai]

Walkthrough

A new "Stopping generation" section is added to docs/ai-chat/custom-agents.mdx. It documents how transport.stopGeneration(chatId) aborts the current custom agent turn via turn.signal, distinguishes turn.stopped outcomes for user-initiated stops versus run cancels, describes turn.complete() behavior when a stop occurs (cleanup and token accumulation without ending the run), provides a streamText code example using abortSignal: turn.signal, and references the hand-rolled loop checklist for equivalent wiring.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description is largely incomplete. While it provides a good summary of the documentation added, it is missing all required checklist items, testing steps, and changelog sections from the template.	Complete the PR description by adding the checklist items (marked complete), describing testing steps, and providing the changelog entry as specified in the repository template.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely summarizes the main change: adding documentation for stopping generation in custom agents, which matches the changeset perfectly.
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.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch docs/custom-agents-stopping-generation

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[coderabbitai]

Actionable comments posted: 1

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: f6f553eb-676b-42f5-8973-f75c3513897b

📥 Commits

Reviewing files that changed from the base of the PR and between 4e919e7 and 26a7c14.

📒 Files selected for processing (1)

• docs/ai-chat/custom-agents.mdx

📜 Review details

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

• GitHub Check: Analyze (javascript-typescript)

🧰 Additional context used

📓 Path-based instructions (1)

docs/**/*.mdx

📄 CodeRabbit inference engine (docs/CLAUDE.md)

docs/**/*.mdx: MDX documentation pages must include frontmatter with title (required), description (required), and sidebarTitle (optional) in YAML format
Use Mintlify components for structured content: , , , , , , /, /
Always import from @trigger.dev/sdk in code examples (never from @trigger.dev/sdk/v3)
Code examples must be complete and runnable where possible
Use language tags in code fences: typescript, bash, json

Files:

• docs/ai-chat/custom-agents.mdx

🧠 Learnings (4)

📚 Learning: 2026-03-10T12:44:14.176Z

Learnt from: nicktrn
Repo: triggerdotdev/trigger.dev PR: 3200
File: docs/config/config-file.mdx:353-368
Timestamp: 2026-03-10T12:44:14.176Z
Learning: In the trigger.dev repo, docs PRs are often companions to implementation PRs. When reviewing docs PRs (MDX files under docs/), check the PR description for any companion/related PR references and verify that the documented features exist in those companion PRs before flagging missing implementations. This ensures docs stay in sync with code changes across related PRs.

Applied to files:

• docs/ai-chat/custom-agents.mdx

📚 Learning: 2026-04-30T20:30:29.458Z

Learnt from: ericallam
Repo: triggerdotdev/trigger.dev PR: 3226
File: docs/ai-chat/quick-start.mdx:13-13
Timestamp: 2026-04-30T20:30:29.458Z
Learning: In this repo’s documentation MDX files (`docs/**/*.mdx`), use `ts` and `tsx` (not `typescript`) as the code-fence language tags for TypeScript/TSX snippets. Do not flag `ts`/`tsx` code-fence language tags as incorrect in any docs MDX file, since this is the site-wide Mintlify-compatible convention.

Applied to files:

• docs/ai-chat/custom-agents.mdx

📚 Learning: 2026-06-16T13:14:09.440Z

Learnt from: ericallam
Repo: triggerdotdev/trigger.dev PR: 3964
File: docs/ai-chat/reference.mdx:482-482
Timestamp: 2026-06-16T13:14:09.440Z
Learning: When documenting or reviewing usage of `ChatTurn.complete(source?)` (in `packages/trigger-sdk/src/v3/ai.ts`), note that `source` is optional (`source?: UIMessageStreamable`). Calling `complete()` with no `source` is valid specifically for a final head-start handover (`handover.isFinal`), because the warm partial already contains the response. If examples or guidance omit `source`, ensure they are in this final-hand-over context so they remain correct.

Applied to files:

• docs/ai-chat/custom-agents.mdx

📚 Learning: 2026-06-16T13:14:14.382Z

Learnt from: ericallam
Repo: triggerdotdev/trigger.dev PR: 3964
File: docs/ai-chat/reference.mdx:478-478
Timestamp: 2026-06-16T13:14:14.382Z
Learning: When reviewing RC-gated `ai-chat` docs under `docs/ai-chat/`, don’t immediately flag missing SDK type fields or implementation details just because the field isn’t present on the docs branch yet. Instead, find and cross-check the companion implementation PR that’s intended to land alongside the docs PR, and only report missing/incorrect fields if they are also absent in the companion SDK/type changes.

Applied to files:

• docs/ai-chat/custom-agents.mdx

🪛 LanguageTool

docs/ai-chat/custom-agents.mdx

[uncategorized] ~207-~207: Possible missing preposition found.
Context: ...rn. Read turn.stopped to tell a user stop from a full run cancel: - *User stop...

(AI_HYDRA_LEO_MISSING_TO)

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[uncategorized] ~207-~207: Possible missing comma found.
Context: ...topped to tell a user stop from a full run cancel: - **User stop** (transport.st...

(AI_HYDRA_LEO_MISSING_COMMA)

---

[uncategorized] ~207-~207: Possible missing preposition found.
Context: ...ed to tell a user stop from a full run cancel: - **User stop** (transport.stopGener...

(AI_HYDRA_LEO_MISSING_TO)

[devin-ai-integration]

✅ Devin Review: No Issues Found

Devin Review analyzed this PR and found no bugs or issues to report.