Extract GoldenPathCoordinatorService as M4 per-task coordinator (Golden Path synthesis scheduling)

Context

M4 per-task coordinator landscape per learn/agentos/v13-path.md:193. Golden Path synthesis is the final phase of the DreamService REM pipeline — produces sandman_handoff.md with mathematical-weighted-priorities (per operator framing in v13-path.md:312: "way less cognitive load").

Sibling-precedent shape: #11062 (BackupCoordinatorService).

The Problem

Currently synthesizeGoldenPath() runs:

1. As phase 5 inside Sandman REM pipeline (per-session)
2. Via autoGoldenPath: true startup flag (operator-disabled per safety pause)
3. Inline at end of DreamService.processUndigestedSessions()

Without orchestrator-driven scheduling, Golden Path can't refresh independently of full REM cycle (e.g., faster cadence for handoff freshness without paying full Tri-Vector extraction cost).

Architectural Reality

Open question for pickup: does Golden Path scheduling belong inside SandmanCoordinatorService (#11065) as part of the REM pipeline, or as its own coordinator with independent cadence (e.g., sandman_handoff.md refresh every 30min vs full REM cycle every 24h)? Per v13-path.md:193 they're separate coordinators. Pickup-time /ticket-intake validates.

DreamService restoration thesis (v13-path.md:195, 312): the cognitive-load offload comes from sandman_handoff.md daemon-driven freshness. Golden Path's faster-cadence-than-Sandman model would directly serve that.

Acceptance Criteria

• /ticket-intake validates separate-coordinator vs fold-into-Sandman
• If separate: ai/daemons/services/GoldenPathCoordinatorService.mjs per #11062 sibling shape
• If fold: close as duplicate of #11065 with rationale
• Wire-in via cadenceEngine.runIfDue
• Cross-family review per pull-request §6.1

Dependencies

• Hard: Blocked by #11062 + #11065 merge (post-Sub-4 wire-in + Sandman cadence interaction)
• Pickup-time intake mandate: detailed prescription deferred

Out of Scope

• Detailed prescription pre-staged here
• DreamService.synthesizeGoldenPath logic (exists; this is scheduling)

Related

• Parent landscape: #11022 (M3.5 epic) → M4 successor
• Siblings: #11062, #11065, +3 more in batch
• Architectural anchor: learn/agentos/v13-path.md:193, 195, 312
• Source: ai/daemons/services/GoldenPathSynthesizer.mjs

Self-Identification: @neo-opus-4-7 (Claude Opus 4.7, Claude Code) — landscape-visibility filing 2026-05-10.

Origin Session ID: c2912891-b459-4a03-b2af-154d5e264df1