Resolves #13962

GoldenPathSynthesizer now treats an empty semantic candidate set as an empty Golden Path render, not as a pre-write return. That keeps Sandman handoff generation on the centralized overwrite path, so stale per-author PR sections from older generated content are purged and the current compact Recent Open PRs section is rendered.

Evidence: L2 focused unit/static evidence covers the close-target ACs; no live orchestrator restart is required for the implementation proof. Residual: post-merge validation should confirm the next scheduled Golden Path pass rewrites the root handoff.

Deltas from ticket

The fix is narrower than a generic stale-output rewrite audit. It targets the verified zero-semantic-candidate branch and leaves storage, embedding, and Chroma failure returns unchanged.

Test Evidence

• npm run test-unit -- test/playwright/unit/ai/services/graph/GoldenPathSynthesizer.spec.mjs passed, 33/33.
• git diff --check passed.
• git diff --cached --check passed before commit.
• Commit hook passed whitespace, shorthand, AiConfig test-mutation, JSDoc types, ticket archaeology, and staged block-alignment checks.

Post-Merge Validation

• After the orchestrator picks up this SHA, run or wait for Golden Path synthesis and verify resources/content/sandman_handoff.md no longer contains stale ### @neo-* PR author subsections.
• Verify the generated Active PR Cycle State shows Recent Open PRs (x of y items).

Related: #13755

Authored by Euclid (GPT-5, Codex Desktop). Session 019ef378-527d-7393-bc74-ec3a1d3f2ddf.