Summary

In reply-agent overflow recovery, two edge paths can finalize with no user-visible payload (effectively undefined/empty) instead of a deterministic fallback:

1. meta.error.kind == context_overflow with empty payloads when session reset is unavailable.
2. Overflow error payloads that normalize/filter to empty during reply payload construction.

Steps to reproduce

1. Run main at 98962ed81d26 (package version 2026.2.16).
2. Execute runReplyAgent with an embedded result containing:
   • meta.error.kind: context_overflow
   • either payloads: [] or payload text that normalizes to empty (e.g. whitespace-only error text).
3. Ensure reset is unavailable (no session store/sessionKey/storePath in this run context).
4. Observe finalization output.

Expected behavior

Overflow failure paths should always return a deterministic user-facing fallback payload.

Actual behavior

In the two edge paths above, finalization can return no renderable payload (undefined/empty outcome).

OpenClaw version

2026.2.16 (main @ 98962ed81d26)

Operating system

Ubuntu 25.10

Install method

Source checkout + pnpm

Logs, screenshots, and evidence

Overflow signatures involved include:

• Context overflow: prompt too large
• Context overflow: Summarization failed: 400 {"message":"prompt is too long"}

Code-path pointers:

• src/auto-reply/reply/agent-runner-execution.ts (embedded overflow meta-error handling)
• src/auto-reply/reply/agent-runner.ts (empty payload/finalization path)

Impact and severity

• Affected: any channel hitting overflow edge paths where recovery output is empty/non-renderable.
• Severity: High reliability impact (silent/empty outcomes are hard to triage).
• Frequency: Edge-case, deterministic with targeted conditions.
• Consequence: missing actionable error response to the user/operator.

Additional information

Related upstream work (adjacent but not complete coverage for this path):

• fix: return user-facing error when session reset after compaction failure #1187
• Context overflow after failed compaction should trigger fallback failover #18095
• fix: improve context overflow error messages and docs #18997
• fix: improve context overflow error with diagnostic details #15749
• feat: progressive compaction escalation and mechanical flush fallback #18663
• [Bug] Telegram receives 'Context overflow' errors while dashboard shows correct responses #18719

I have a narrowly scoped fix prepared in my fork that:

1. Forces deterministic overflow fallback when embedded overflow meta-error has zero payloads.
2. Ensures runner finalization uses overflow fallback when payload arrays normalize/filter to empty.
3. Adds two regression tests for those exact paths.