feat(cloud-task): Durable run streaming through agent-proxy by charlesvien · Pull Request #2519 · PostHog/code

charlesvien · 2026-06-08T05:51:10Z

Problem

Moves event streaming to agent-proxy

Changes

Route the event-ingest POST to the standalone agent-proxy via new POSTHOG_TASK_RUN_EVENT_INGEST_URL
Resolve the read leg once via stream_token, then read from the proxy with a run-scoped Bearer token (falls back to Django)
Add a stream-end sentinel as the authoritative end-of-stream signal
Make the reconnect loop status-unaware: stop only on stream-end or budget exhaustion, never on polled status
Speed up reconnect backoff (flat 500ms for 3 attempts, then exponential to 30s; ~1.5s recovery vs ~16s)
Cover ingest routing, read-leg routing and stream-end in tests

How did you test this?

Manually

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charlesvien · 2026-06-08T05:51:23Z

feat(cloud-task): Durable run streaming through agent-proxy #2519 👈 (View in Graphite)
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greptile-apps · 2026-06-08T05:59:29Z

T-Rex Logs

What T-Rex did

Ran the existing cloud task service test file and all 24 tests passed.
Added a focused proxy stream edge-case test file with three tests for proxy URL encoding, stream_token fallback, and stream-end during bootstrap.
Verified that a proxy stream URL with URL-special characters in runId is parsed into the wrong path and query shape when the runId is not encoded.
Observed that the proxy stream URL test timed out due to the malformed URL not matching the mock URL pattern, confirming the URL handling issue.
Verified that stream-end during bootstrap deletes the watcher before historical logs finish loading, so the snapshot is not emitted.
Verified that transient stream_token resolution failures retry resolution on reconnect.
Verified that event-stream-sender.ts encodes runId with encodeURIComponent, preventing read-leg omissions.

Artifacts

Focused proxy stream edge-case test output

Shows the edge-case test results for proxy stream behavior to inspect test outcomes.

URL parsing proof for unencoded proxy run IDs

Demonstrates how unencoded run IDs affect URL path and query shaping.

Generated focused proxy stream edge-case tests

Contains the TypeScript source for the focused proxy stream edge-case tests.

Vitest output: 1 failed (URL encoding bug), 2 passed, 1 unhandled rejection (bootstrap race)

Summarizes the test run results for the proxy edge-case tests, including a failure and a bootstrap race.

Node.js proof: proxy stream URL is malformed when runId contains special chars; ingest URL is correct

Demonstrates how a runId with special characters breaks the constructed URL while the ingestion URL remains correct.

Generated proxy-stream-edge-cases TypeScript tests

Contains the TypeScript tests used for the proxy-stream-edge-cases run.

_{Ran code and verified through T-Rex}

Prompt To Fix All With AI

Fix the following 2 code review issues. Work through them one at a time, proposing concise fixes.

---

### Issue 1 of 2
apps/code/src/main/services/cloud-task/service.ts:654-658
**Encode proxy run IDs**

The proxy stream path inserts `watcher.runId` directly into the URL. If a run ID contains URL-special characters such as `/`, `?`, or `&`, `new URL()` treats those characters as path or query delimiters and the request goes to the wrong proxy route. The ingest side already encodes `runId`, so the read side should do the same.

```suggestion
    const url = new URL(
      usingProxy
        ? `${base}/v1/runs/${encodeURIComponent(watcher.runId)}/stream`
        : `${base}/api/projects/${watcher.teamId}/tasks/${watcher.taskId}/runs/${watcher.runId}/stream/`,
    );
```

### Issue 2 of 2
apps/code/src/main/services/cloud-task/service.ts:1188-1191
**Preserve bootstrap snapshot**

When `stream-end` arrives while bootstrap is still fetching historical logs, this branch stops and deletes the watcher before the bootstrap path can emit its snapshot. The pending `bootstrapWatcher()` then sees that the watcher is gone and returns, so subscribers never receive the existing run history. The `streamEnded && isBootstrapping` case needs to defer stopping until after bootstrap finishes.

_{Reviews (1): Last reviewed commit: "Implement agent proxy" | Re-trigger Greptile}

greptile-apps · 2026-06-08T05:59:33Z

    const url = new URL(
-      `${watcher.apiHost}/api/projects/${watcher.teamId}/tasks/${watcher.taskId}/runs/${watcher.runId}/stream/`,
+      usingProxy
+        ? `${base}/v1/runs/${watcher.runId}/stream`
+        : `${base}/api/projects/${watcher.teamId}/tasks/${watcher.taskId}/runs/${watcher.runId}/stream/`,
    );


Encode proxy run IDs

The proxy stream path inserts watcher.runId directly into the URL. If a run ID contains URL-special characters such as /, ?, or &, new URL() treats those characters as path or query delimiters and the request goes to the wrong proxy route. The ingest side already encodes runId, so the read side should do the same.

Suggested change

const url = new URL(

`${watcher.apiHost}/api/projects/${watcher.teamId}/tasks/${watcher.taskId}/runs/${watcher.runId}/stream/`,

usingProxy

? `${base}/v1/runs/${watcher.runId}/stream`

: `${base}/api/projects/${watcher.teamId}/tasks/${watcher.taskId}/runs/${watcher.runId}/stream/`,

);

const url = new URL(

usingProxy

? `${base}/v1/runs/${encodeURIComponent(watcher.runId)}/stream`

: `${base}/api/projects/${watcher.teamId}/tasks/${watcher.taskId}/runs/${watcher.runId}/stream/`,

);

Artifacts

Malformed proxy stream URL proof

Keeps the command output available without making the summary code-heavy.

Focused proxy stream edge-case test output

Keeps the command output available without making the summary code-heavy.

_{Ran code and verified through T-Rex}

Prompt To Fix With AI

This is a comment left during a code review. Path: apps/code/src/main/services/cloud-task/service.ts Line: 654-658 Comment: **Encode proxy run IDs** The proxy stream path inserts `watcher.runId` directly into the URL. If a run ID contains URL-special characters such as `/`, `?`, or `&`, `new URL()` treats those characters as path or query delimiters and the request goes to the wrong proxy route. The ingest side already encodes `runId`, so the read side should do the same. ```suggestion const url = new URL( usingProxy ? `${base}/v1/runs/${encodeURIComponent(watcher.runId)}/stream` : `${base}/api/projects/${watcher.teamId}/tasks/${watcher.taskId}/runs/${watcher.runId}/stream/`, ); ``` <details><summary>Artifacts</summary> **[Malformed proxy stream URL proof](https://app.greptile.com/trex/artifacts/ddb62d93-805a-4883-af2f-93bfa316a395)** - Keeps the command output available without making the summary code-heavy. **[Focused proxy stream edge-case test output](https://app.greptile.com/trex/artifacts/195501f6-4213-4d1e-9e91-701e80403f1a)** - Keeps the command output available without making the summary code-heavy. </details> <a href="https://www.greptile.com/trex"><img alt="T-Rex" src="https://greptile-static-assets.s3.amazonaws.com/trex/trex_green.svg" height="14" align="absmiddle"></a> Ran code and verified through T-Rex How can I resolve this? If you propose a fix, please make it concise.

greptile-apps · 2026-06-08T05:59:34Z

+    if (watcher.streamEnded) {
+      this.emitStatusUpdate(watcher);
+      this.stopWatcher(key);
+      return;


Preserve bootstrap snapshot

When stream-end arrives while bootstrap is still fetching historical logs, this branch stops and deletes the watcher before the bootstrap path can emit its snapshot. The pending bootstrapWatcher() then sees that the watcher is gone and returns, so subscribers never receive the existing run history. The streamEnded && isBootstrapping case needs to defer stopping until after bootstrap finishes.

Artifacts

Focused stream-end during bootstrap repro output

Keeps the command output available without making the summary code-heavy.

_{Ran code and verified through T-Rex}

Prompt To Fix With AI

This is a comment left during a code review. Path: apps/code/src/main/services/cloud-task/service.ts Line: 1188-1191 Comment: **Preserve bootstrap snapshot** When `stream-end` arrives while bootstrap is still fetching historical logs, this branch stops and deletes the watcher before the bootstrap path can emit its snapshot. The pending `bootstrapWatcher()` then sees that the watcher is gone and returns, so subscribers never receive the existing run history. The `streamEnded && isBootstrapping` case needs to defer stopping until after bootstrap finishes. <details><summary>Artifacts</summary> **[Focused stream-end during bootstrap repro output](https://app.greptile.com/trex/artifacts/195501f6-4213-4d1e-9e91-701e80403f1a)** - Keeps the command output available without making the summary code-heavy. </details> <a href="https://www.greptile.com/trex"><img alt="T-Rex" src="https://greptile-static-assets.s3.amazonaws.com/trex/trex_green.svg" height="14" align="absmiddle"></a> Ran code and verified through T-Rex How can I resolve this? If you propose a fix, please make it concise.

github-actions · 2026-06-09T22:36:09Z

React Doctor found no issues in the changed files. 🎉

_{Reviewed by React Doctor for commit 72c2661.}

greptile-apps · 2026-06-10T05:20:01Z

T-Rex Logs

What T-Rex did

Generated focused checks for the cloud-task stream read path and bootstrap completion flow.
Verified that proxy stream URLs are built with the raw run ID when the read leg uses agent-proxy.
Verified that a stream-end event during bootstrap can stop the watcher before the snapshot is emitted.
Wrote targeted repro test at apps/code/src/main/services/cloud-task/trex-bugs.test.ts using the same mock patterns as the existing test suite.
Ran the tests with npx vitest run from the apps/code workspace; both tests failed as expected.
Test 1 showed that stream-end during bootstrap timed out waiting for the snapshot emission, confirming the watcher was stopped before the snapshot could be emitted.
Test 2 demonstrated an encoding discrepancy in the proxy URL, where plus and slash characters were not encoded as encodeURIComponent would encode them.
Full verbose test output was saved to trex-artifacts/trex-test-output.log.

Artifacts

Verbose targeted test output

Contains the targeted test run output for the cloud-task stream read path repros, used to inspect test results.

Generated repro tests

Contains the TypeScript repro tests generated using the same mock patterns as the existing test suite.

Verbose vitest output showing both failing repro tests with stack traces

Contains verbose test output showing both failing repro tests, including stack traces.

trex-bugs.test.ts repro source

Contains the targeted repro test file trex-bugs.test.ts used for the cloud-task repros.

_{Ran code and verified through T-Rex}

_{Reviews (2): Last reviewed commit: "Implement agent proxy" | Re-trigger Greptile}

charlesvien changed the title ~~Implement agent proxy~~ feat(cloud-task): Durable run streaming through agent-proxy Jun 8, 2026

greptile-apps Bot reviewed Jun 8, 2026

View reviewed changes

charlesvien force-pushed the 06-06-durable_streaming branch from 3d4147e to 10228ed Compare June 9, 2026 22:35

charlesvien marked this pull request as ready for review June 10, 2026 05:13

charlesvien force-pushed the 06-06-durable_streaming branch from 10228ed to 18eff20 Compare June 11, 2026 06:16

charlesvien added 3 commits June 11, 2026 01:08

Implement agent proxy

47fa0d5

format cloud-task log call

83dd6d6

fix workspace-server vite externals for rolldown

72c2661

charlesvien force-pushed the 06-06-durable_streaming branch from 56e595e to 72c2661 Compare June 11, 2026 08:08

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feat(cloud-task): Durable run streaming through agent-proxy#2519

feat(cloud-task): Durable run streaming through agent-proxy#2519
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