Safe outputs MCP server returns success but outputs.jsonl is empty (v0.65.5)

[yaananth]

Bug Report

Summary

The safe outputs MCP server accepts tools/call requests and returns {"result":"success"} to the agent, but never persists items to outputs.jsonl. This causes agent_output.json to be {"items":[]}, which means downstream jobs (safe_outputs, custom safe-output jobs like slack_handoff_notify) have nothing to process.

Reproduction

• Failing run: https://github.com/github/copilot-sre/actions/runs/23902903652
• Workflow: oncall-handoff-notes (schedule trigger, claude-opus-4.6)
• gh-aw version: v0.65.5 (github/gh-aw-actions/setup@15b2fa31e9a1b771c9773c162273924d8f5ea516)
• Date: 2026-04-02

Evidence

1. Agent called both safe output tools successfully:

   • create_discussion at 13:43:37Z → response: {"result":"success"}
   • slack_handoff_notify at 13:43:47Z → response: {"result":"success"}

2. MCP Gateway confirmed healthy:

   • safeoutputs server: 2 requests, 2 tool calls, 0 errors, 0% error rate

3. But outputs were never persisted:

   • safe-output-items.jsonl = 0 bytes (empty)
   • agent_output.json = {"items":[]}
   • safe_outputs job had nothing to process
   • slack_handoff_notify job was skipped (contains(needs.agent.outputs.output_types, 'slack_handoff_notify') = false)

4. RPC messages confirm full payloads were sent:

   • create_discussion payload included title + full markdown body (~76KB)
   • slack_handoff_notify payload included channel, handles, discussion_title, target_repo, week_of
   • Both received proper {"result":"success"} responses from the HTTP MCP backend

5. All 8 prior weekly runs (Feb 5 - Mar 26) worked correctly — they all had 1-2 items in agent_output.json

Impact

• Discussion was never created in the target repo
• Slack notification was never sent
• Workflow reported conclusion: success despite producing no output
• Required manual mitigation (GraphQL discussion creation + direct Slack API call)

Expected Behavior

Items passed to the safe outputs MCP server via tools/call should be persisted to outputs.jsonl so that downstream jobs can process them.

Workaround

Pinned back to v0.65.4 via gh aw compile oncall-handoff-notes --action-tag v0.65.4 as a mitigation.

[yaananth]

Closing — this was a user-side bug, not a gh-aw framework issue.

Root cause: Our workflow had GH_AW_SAFE_OUTPUTS: "/tmp/gh-aw/safeoutputs/outputs.jsonl" in the workflow-level env: section. This hardcoded /tmp/... path shadowed the framework's ${{ runner.temp }}/gh-aw/safeoutputs/outputs.jsonl path that the ingestion step (collect_ndjson_output.cjs) reads from.

The safe outputs MCP HTTP server inherited the workflow-level env and wrote to /tmp/..., while the collection step read from $RUNNER_TEMP/... — two different paths on GitHub-hosted runners. Hence outputs.jsonl appeared empty at the collection path.

This was latent for a while and only surfaced with AWF 0.25.10 (shipped in v0.65.5) which changed how the sandbox container handles environment propagation / /tmp mounts.

Fix: Removed the GH_AW_SAFE_OUTPUTS override from the workflow env: — the framework manages this path and workflows should not set it.

Suggestion for gh-aw team: Consider emitting a compile-time warning when a workflow sets GH_AW_SAFE_OUTPUTS in its env: section, since this is a framework-managed variable that should never be user-overridden.