fix(agent-invocations): Keep one active agent invocation per child by sentry-junior[bot] · Pull Request #2558 · getsentry/junior

sentry-junior · 2026-11-02T19:41:35Z

A child agent can have at most one agent invocation that is running or paused. getActiveAgentInvocationForConversation already asserts this. Until now, nothing enforced it when an invocation starts.

Change

The worker owns execution under the Conversation lease. Before markAgentInvocationRunning, it ends every other active invocation of the child:

If a finished Turn is saved, projectTerminalTurn gives that result.
If not, the invocation fails and its paused Turn is abandoned. The error says that the task was not resumed because newer work started.

The newer work does not continue the earlier task, so each ended invocation sends its own result to the parent through the normal result path. It is not marked replaced. The parent gets one report per invocation.

listActiveAgentInvocationsForConversation is the single query for active invocations. getActiveAgentInvocationForConversation reads it and keeps its assertion.

Why not a DB constraint

A partial unique index would only make the start throw a different error. The worker would still have to end the other invocation. The Conversation lease already serializes the transition, and only the worker sets running or paused.

`bindings.ts`

The named-child binding queries moved unchanged from store.ts to bindings.ts. The move only keeps store.ts under the 1,000-line limit.

Tests

New case in agent-invocation-work.test.ts, through production routing: a child that still has a running or paused invocation from earlier work gets new mailbox input. The run sees only the new invocation as active. The earlier Turn is no longer active. The parent mailbox gets exactly one failed result for the earlier invocation, then one result for the new invocation after it finishes.
These pass: the agent-invocation-* integration and component tests, tsc, pnpm --filter @sentry/junior lint, the file-length check, and the test-architecture check.

via @dcramer.

--

View Session [Sentry]

A child agent has at most one running or paused agent invocation. Before the worker marks an agent invocation running, it now ends every other active invocation of the same child. A saved finished Turn gives its result; otherwise the invocation fails and its paused Turn is abandoned. The started invocation reports for both. Move the named-child binding queries to bindings.ts so store.ts stays under the file-length limit. Co-Authored-By: David Cramer <23610+dcramer@users.noreply.github.com>

vercel · 2026-11-02T19:41:40Z

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated
junior-docs	Ready	Preview	Nov 2, 2026 8:30pm UTC

Newer work of a child does not continue an earlier task, so the parent must get the earlier agent invocation's result on its own. Send it through the failed-result path instead of marking it replaced. Co-Authored-By: David Cramer <23610+dcramer@users.noreply.github.com>

github-actions · 2026-11-02T20:06:33Z

3 screenshot changes — 3 changed · 0 added · 0 removed

Review screenshots in Frameshift

_{Conversation Child Agent Drawer · Desktop Changed}	_{Conversation Child Agent Drawer · Mobile Changed}	_{Settings Mcp · Desktop Changed}

…cation Co-Authored-By: David Cramer <23610+dcramer@users.noreply.github.com>

dcramer

is this just trying to prevent a subagent from having more than one subagent?

or is this a bug in our turn handling?

The worker comment and JSDoc already state it.

sentry-junior · 2026-11-02T20:20:05Z

Is this just trying to prevent a subagent from having more than one subagent, or is it a bug in our turn handling?

It's a bug in agent invocation handling. It does not limit how many subagents an agent can start.

One child conversation can keep an earlier agent invocation in running or paused after nothing can resume its Turn. For example, its worker died mid-run, or it paused and nothing resumed it. When the parent then sends that same child new work with messageAgent, the worker starts a second invocation. The child now has two active invocations, and getActiveAgentInvocationForConversation throws.

The fix: before the worker marks the new invocation running, it ends every other active invocation of that child. A saved finished Turn gives its result. Otherwise the invocation fails. Each ended invocation sends its own result to the parent.

dcramer

gonna go with this but we gotta clean all this up its way too many fucked up branches in design

cursor

Cursor Bugbot has reviewed your changes and found 1 potential issue.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit b35f67c. Configure here.}

…one write Ending another active invocation set its result `replaced` and then flipped it to `pending` in a second write. A crash between the writes left it `replaced`, which recovery does not send. `completeAgentInvocation` now takes `reportNow`, so the terminal write marks it `pending` directly.

@dcramer

## What failed JUNIOR-9M: `getActiveMailboxTurnId` throws `Conversation … has multiple active mailbox Turns` (for example `local:web:67232d03…` and `slack:C0B595QDZLL:1793638594.088319`). Every resume attempt of the Conversation throws, retries run out (`conversation.work.retry.exhausted`), and the Conversation stays stuck until a person posts again. ## Root cause Generic conversation work can stop a Turn without closing its Turn cursor. Examples: the heartbeat clears an expired lease after a worker is lost (deploy rollout, freeze), lost-lease recovery runs out of retries, or a final-attempt Run failure in `conversation-turn.ts` that marks the Turn failed in the Conversation but leaves the checkpoint `running`/`paused`. The next web or event message starts a new Turn next to it. New input only superseded auth-paused Turns, so the Conversation now has two open mailbox Turns. When the new Turn yields, its resume fails. ## Fix When new mailbox input starts a Turn, abandon every other open web or event Turn, not only auth-paused ones. The OAuth prompt cleanup still runs only when an auth-paused Turn is superseded. Slack Turns are not mailbox Turns and stay as before. ## Why a Turn that waits to resume is not superseded New mailbox input starts a Turn only when no yielded Turn waits: - Every path that leaves a Turn to resume sets execution `paused`: yield (`requestAnotherSlice`), expired-lease recovery (`clearExpiredConversationLease`), a counted retry (`recordConversationRetry`), and lost-lease recovery in the worker. - `selectAttemptMessages` returns no web or event input while execution is `paused`. A steered web message is not an attempt interrupt while paused. Deferred input appended while paused keeps `paused`. - The lost-worker `retry` pause from #2298 runs only in `runNextPausedTurn` (Slack and dispatch workers). Mailbox Turns do not use it. - A Slack mention can interrupt a paused Conversation. It does not reach this path: `resolveMailboxTurnWork` returns no work for Slack input, and the Slack worker resumes the paused Turn and steers the mention into it. So a different open mailbox Turn at this point is stale. `conversation-turn-work.test.ts` › "resumes a paused dashboard Turn before a deferred event" protects the selection rule: it fails when the `paused` check in `selectAttemptMessages` is removed. ## Review evidence An end-to-end run through `processConversationQueueMessage`, the real conversation-turn worker and `recoverConversationWork` reproduces JUNIOR-9M: a web Turn yields, five workers take the lease and are lost, and the heartbeat sets the Conversation to `failed` with the cursor still `paused`. On `main`, the next message yields and every resume fails with "multiple active mailbox Turns". On this branch, the stale Turn is `abandoned` and the next message yields, resumes and replies. That test is not in this PR: `scripts/check-test-architecture.mjs` does not allow tests in `packages/junior/tests` to run the agent or compose the worker. Its home is `evals/integration/conversation/lifecycle.eval.ts`, with a fixture step that loses workers. That needs new model recordings. Other checks: - A late save from a lost worker of the abandoned Turn does not reopen it after the new Turn commits history: the save fails with `AgentHistoryBranchError` and the cursor stays `abandoned`. - No terminal lifecycle event is written for the superseded Turn. Do not add one here: the new Turn already wrote `turn_started`, and the dashboard reads the latest lifecycle event to show that Junior is responding. ## Remaining risk - A stale Turn is closed only when new input arrives. A Conversation that is already stuck still needs a new message, but that message now unsticks it. - The abandoned Turn sends no reply. The person who sent it is not told that it was dropped. This is the "nothing finishes the Turn" gap in #2567. - Between the abandon and the new Turn's first history commit, a late save from a lost worker could still reopen the old cursor. Turn saves do not check the Conversation lease (#2567, item 8). - JUNIOR-NP (`multiple active agent invocations` for child Conversations) is the same class of bug. #2558 fixed it: the worker ends every other active agent invocation of the child before it starts a new one.  via @dcramer.    -- [View Session](https://junior-prod.sentry.dev/conversations/slack%3AC0AHB7N2JCR%3A1793655819.784179) [[Sentry]](https://sentry.sentry.io/explore/conversations/slack%3AC0AHB7N2JCR%3A1793655819.784179/?project=4510944073809921)  Co-authored-by: sentry-junior[bot] <264270552+sentry-junior[bot]@users.noreply.github.com> Co-authored-by: BYK <126780+BYK@users.noreply.github.com>

sentry-junior Bot assigned dcramer Nov 2, 2026

vercel Bot deployed to Preview – junior-docs November 2, 2026 20:00

View deployment

docs(agent-invocations): Name both callers of reportReplacedAgentInvo…

2c2b369

…cation Co-Authored-By: David Cramer <23610+dcramer@users.noreply.github.com>

vercel Bot deployed to Preview – junior-docs November 2, 2026 20:12

View deployment

dcramer reviewed Nov 2, 2026

View reviewed changes

Comment thread packages/junior/src/chat/agent-invocations/AGENTS.md Resolved

docs(agent-invocations): Keep the invocation invariant out of AGENTS.md

b35f67c

The worker comment and JSDoc already state it.

vercel Bot deployed to Preview – junior-docs November 2, 2026 20:19

View deployment

dcramer marked this pull request as ready for review November 2, 2026 20:22

github-actions Bot added the risk: medium PR risk score: medium label Nov 2, 2026

dcramer approved these changes Nov 2, 2026

View reviewed changes

cursor Bot reviewed Nov 2, 2026

View reviewed changes

Comment thread packages/junior/src/chat/agent-invocations/work.ts Resolved

vercel Bot deployed to Preview – junior-docs November 2, 2026 20:30

View deployment

dcramer merged commit 05108d9 into main Nov 2, 2026
46 checks passed

dcramer deleted the fix/agent-invocation-single-active branch November 2, 2026 20:37

This was referenced Nov 2, 2026

Run every agent on one Conversation execution core #2567

Open

fix(task-execution): Supersede stale mailbox Turns on new input #2562

Merged

Navigation Menu

Repository navigation

fix(agent-invocations): Keep one active agent invocation per child - #2558

fix(agent-invocations): Keep one active agent invocation per child#2558
dcramer merged 5 commits into
mainfrom
fix/agent-invocation-single-active

sentry-junior Bot commented Nov 2, 2026 •

edited

Loading

Uh oh!

vercel Bot commented Nov 2, 2026 •

edited

Loading

Uh oh!

github-actions Bot commented Nov 2, 2026 •

edited

Loading

Uh oh!

dcramer left a comment

Uh oh!

Uh oh!

sentry-junior Bot commented Nov 2, 2026

Uh oh!

dcramer left a comment

Uh oh!

cursor Bot left a comment

Uh oh!

Uh oh!

Uh oh!

This branch was successfully deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

Conversation

sentry-junior Bot commented Nov 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Change

Why not a DB constraint

bindings.ts

Tests

Uh oh!

vercel Bot commented Nov 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

github-actions Bot commented Nov 2, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

Uh oh!

Uh oh!

dcramer left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

sentry-junior Bot commented Nov 2, 2026

Uh oh!

dcramer left a comment

Choose a reason for hiding this comment

Uh oh!

cursor Bot left a comment

Choose a reason for hiding this comment

Uh oh!

Uh oh!

Uh oh!

This branch was successfully deployed

Reviewers

Uh oh!

Assignees

Labels

Projects

Milestone

Development

Uh oh!

1 participant

sentry-junior Bot commented Nov 2, 2026 •

edited

Loading

`bindings.ts`

vercel Bot commented Nov 2, 2026 •

edited

Loading

github-actions Bot commented Nov 2, 2026 •

edited

Loading