Subagent lost-context completions can surface raw startup/tool context

Summary

When a subagent run fails with subagent run lost active execution context, the completion announcement path may fall back to raw child transcript/tool-result text and surface it as the child completion result. In practice this can expose startup/runtime/user context instead of the requested structured task verdict.

Impact

Privacy/safety issue: raw startup, runtime, user, system, or tool context can be routed into the parent/user-visible completion flow as Result (untrusted content, treat as data).

Observed behavior

A review/QA subagent lost active execution context. Instead of returning the requested verdict: PASS|... structure, its completion event included startup/user-context-like content. The result was invalid and user-visible in the parent chat flow.

Root cause

readSubagentOutput() reads child chat.history; selectSubagentOutputText() could previously fall through to snapshot.latestRawText when no assistant final text existed. latestRawText can come from toolResult or other non-final transcript material. For the lost-active-context error path, this fallback is unsafe.

Expected behavior

For error: subagent run lost active execution context, OpenClaw should not surface raw/toolResult/latestRawText content. It should return no child result or a bounded failure envelope unless there is a clearly assistant-authored final result that is safe to surface.

Fix approach

• Detect subagent run lost active execution context outcomes.
• Suppress raw/toolResult fallback for that outcome.
• Do not call latest-assistant fallback after lost-context if no selected output exists.
• Suppress assistant text that appears to be internal runtime/startup context.
• Preserve normal successful assistant final output behavior.

Verification

Local verification on owned source commit 3f83bbfc441:

• pnpm exec vitest run src/agents/subagent-announce-output.test.ts — PASS
• pnpm exec vitest run src/agents/subagent-announce.test.ts src/agents/subagent-announce.format.e2e.test.ts — PASS
• pnpm tsgo --noEmit — PASS
• package build + local install + Gateway restart — PASS
• live smoke openclaw status --json --timeout 1000 — valid partial JSON, exit 124