feat(sdk): chat sessions accept concurrencyKey and trigger-time named limits

[matt-aitken]

Summary

Stacked on #4853. Chat agents already accept the task-level concurrency option, but the session trigger path had no way to scope runs per chat or tenant. Session trigger config now carries concurrencyKey and up to two trigger-time named limits, so a chat agent declaring concurrency: { perKey: 1 } can actually get one run per tenant by passing a key when the session starts:

const start = chat.createStartSessionAction("support-chat", {
  triggerConfig: { concurrencyKey: user.id },
});

Design

The two fields ride the existing session trigger config, so every run the session schedules (initial, continuation, and upgrade re-triggers) carries them through one choke point on the server. All three session starters forward them: chat.createStartSessionAction, the browser AgentChat client, and handover. Named limits are validated client-side with the same rules and error messages as tasks.trigger.

The key is never defaulted from the chat ID: a session without an explicit concurrencyKey shares the task's keyless pool, so existing chat agents keep their current concurrency accounting.

[changeset-bot]

🦋 Changeset detected

Latest commit: d511299

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 27 packages

Name	Type
@trigger.dev/sdk	Patch
@trigger.dev/core	Patch
@trigger.dev/python	Patch
@internal/dashboard-agent	Patch
@trigger.dev/build	Patch
trigger.dev	Patch
@trigger.dev/redis-worker	Patch
@trigger.dev/schema-to-json	Patch
@internal/clickhouse	Patch
@internal/llm-model-catalog	Patch
@internal/metrics-pipeline	Patch
@trigger.dev/rbac	Patch
@internal/redis	Patch
@internal/replication	Patch
@internal/run-engine	Patch
@internal/run-store	Patch
@internal/schedule-engine	Patch
@internal/tracing	Patch
@internal/webhook-engine	Patch
@internal/webhook-sources	Patch
@internal/cache	Patch
@trigger.dev/react-hooks	Patch
@trigger.dev/rsc	Patch
@trigger.dev/database	Patch
@trigger.dev/otlp-importer	Patch
@trigger.dev/sso	Patch
@internal/testcontainers	Patch

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Walkthrough

The change adds shared validation for named concurrency limits and adds concurrency and concurrencyKey to SessionTriggerConfig. Chat session start actions and AgentChat forward these values, with per-call values taking precedence. Webhook delivery validates configuration only for new sessions. Triggered runs receive the configured values. Tests and documentation cover precedence, omission, clearing, and invalid names.

Priority: ⬇️ Low

Merge Risk: 🟡 Moderate · up to dfe4e

When two requests both start the same chat session at nearly the same time, whichever request's configuration loses the race can silently override the intended per-session concurrency limits or key, so the session may not get the concurrency scoping the caller expects. This should be fixed with a create-if-absent write before merging, though it is a narrow timing window rather than a broad outage risk.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the change and its design, but it omits the required issue reference, checklist, testing details, changelog section, and screenshots section.	Add the required template sections. Include a Closes # reference, complete the checklist, describe testing performed, add a short changelog entry, and address screenshots or mark them as not applicable.
Docstring Coverage	⚠️ Warning	Docstring coverage is 55.56% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 9 files. (2 skipped: 2…	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: support for concurrencyKey and trigger-time named limits in chat sessions.
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.

Full details: Docstring Coverage

Explanation

Docstring coverage is 55.56% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 9 functions across 9 files. (2 skipped: 2 unsupported.)

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commit: d511299

[matt-aitken]

Closing: this stack was flattened into a single change that has now been merged and will land in this repository via the automated sync. All review feedback from these PRs is incorporated, along with further review rounds on the flattened change.