PR #73637: fix(agents): preserve extraSystemPrompt under systemPromptOverride (#73624)

• Repository: openclaw/openclaw
• Author: hclsys
• State: closed | merged: False
• Link: https://github.com/openclaw/openclaw/pull/73637

Description (problem / solution / changelog)

What

Fixes #73624. Subagent spawns under agents configured with an agent-level systemPromptOverride silently drop the per-run extraSystemPrompt (the ## Your Role block built by buildSubagentSystemPrompt). The spawned child then gets the bootstrap user message ("Begin. Your assigned task is in the system prompt under Your Role; execute it to completion.") with no ## Your Role to read, and behaves confused — searching context/memory for a task that was never delivered.

Root cause

subagent-spawn.ts:1073 plumbs the subagent role/task block through the extraSystemPrompt parameter. Three call sites then assemble the final system prompt with the same shape:

const builtSystemPrompt =
  resolveSystemPromptOverride({ config, agentId }) ??
  buildEmbeddedSystemPrompt({ ..., extraSystemPrompt, ... });

When the override is non-null, buildEmbeddedSystemPrompt is short-circuited and extraSystemPrompt is discarded.

The reporter (@jarviskar) localized the regression to dist/selection-D9uTvvsw.js line 433 of buildLogger-era bundling, which corresponds to this ?? chain at three production call sites:

• src/agents/pi-embedded-runner/run/attempt.ts — embedded-runner per-attempt system prompt
• src/agents/pi-embedded-runner/compact.ts — compaction-driven retry system prompt
• src/agents/cli-runner/prepare.ts — CLI agent-harness system prompt

Fix

Add a small combineSystemPromptOverrideWithExtra({ override, extraSystemPrompt }) helper next to resolveSystemPromptOverride and use it at all three call sites:

combineSystemPromptOverrideWithExtra({
  override: resolveSystemPromptOverride({ config, agentId }),
  extraSystemPrompt: params.extraSystemPrompt,
}) ??
buildEmbeddedSystemPrompt({ ..., extraSystemPrompt, ... });

Behavior:

• No override → returns undefined, falls back to existing buildEmbeddedSystemPrompt / buildSystemPrompt (no behavior change for agents without an override).
• Override + no extra → returns the trimmed override unchanged (matches today's behavior for non-subagent runs).
• Override + extra → returns "<override>\n\n<extra>" so the spawned subagent's compiled system prompt contains both the agent persona and the ## Your Role block.

Pre-implement audit

1. Existing-helper check (vincentkoc #57341). grep finds resolveSystemPromptOverride co-located in system-prompt-override.ts. The new combineSystemPromptOverrideWithExtra ships next to it as the natural extension, not in a new helper module. ✅
2. Shared-helper caller check (steipete #60623). All three call sites already compose resolveSystemPromptOverride against buildEmbeddedSystemPrompt / buildSystemPrompt and already accept extraSystemPrompt in their builder params, so the contract change is consistent across them. The existing builders' extraSystemPrompt handling is unchanged — only the override branch now folds it in. ✅
3. Broader-fix rival scan (steipete #68270). Zero rival PRs reference #73624. ✅

Test changes

Three new cases in src/agents/system-prompt-override.test.ts:

• returns undefined when no override is present so callers fall back — pins the no-override path so the existing fallback to buildEmbeddedSystemPrompt keeps working.
• returns the override alone when extraSystemPrompt is missing or blank — covers non-subagent runs (no behavior change).
• appends the trimmed extraSystemPrompt with a blank line separator — pins the regression case from #73624 so ## Your Role is preserved when the override is set.

Verified locally

npx oxlint src/agents/system-prompt-override.ts src/agents/system-prompt-override.test.ts \
  src/agents/pi-embedded-runner/run/attempt.ts src/agents/pi-embedded-runner/compact.ts \
  src/agents/cli-runner/prepare.ts
# Found 0 warnings and 0 errors.

npx vitest run src/agents/system-prompt-override.test.ts \
  src/agents/cli-runner/prepare.test.ts \
  src/agents/pi-embedded-runner/run/attempt.prompt-helpers.test.ts
# Tests  34 passed (34)

lobster-biscuit: 73624-subagent-extra-system-prompt-fold

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Changed files

• CHANGELOG.md (modified, +1/-0)
• src/agents/cli-runner/prepare.ts (modified, +13/-4)
• src/agents/pi-embedded-runner/compact.ts (modified, +13/-4)
• src/agents/pi-embedded-runner/run/attempt.ts (modified, +15/-4)
• src/agents/system-prompt-override.test.ts (modified, +67/-1)
• src/agents/system-prompt-override.ts (modified, +55/-0)