Summary

• Migrates boulder state from singleton .sisyphus/boulder.json (last-write-wins) to per-plan .sisyphus/boulders/{plan-name}.json files, enabling multiple plans to execute concurrently without conflicts
• Adds an in-memory Map<sessionID, planName> tracker (plan-name-tracker.ts) with disk-scan fallback (findBoulderForSession) for the CLI run process (separate process, no shared memory)
• All 6 consumer hooks migrated to plan-aware storage; full backward compatibility preserved via optional planName parameter (existing API unchanged)

Problem

The singleton .sisyphus/boulder.json is the only bottleneck preventing parallel multi-plan execution. When two plans run concurrently, the last writer wins and corrupts the other plan's state. Evidence and notepad paths are already plan-name isolated — only the boulder file was missing this isolation.

Solution

Per-plan boulder files at .sisyphus/boulders/{plan-name}.json:

• start-work writes to the per-plan path and registers sessionID → planName in memory
• All consumers resolve the plan-aware path via getSessionPlanName(sessionID) (in-memory, fast) with findBoulderForSession(dir, sessionID) (disk scan) as fallback
• Legacy .sisyphus/boulder.json still works — findBoulderForSession and appendSessionId both fall back to it when no per-plan file exists

Changes

Storage layer (src/features/boulder-state/):

• constants.ts — Added BOULDERS_DIR = "boulders" and BOULDERS_BASE_PATH
• storage.ts — Optional planName? on 5 I/O functions; new findBoulderForSession() with legacy fallback; appendSessionId falls back to legacy path when per-plan file doesn't exist
• plan-name-tracker.ts — New: in-memory Map<sessionID, planName> with setSessionPlanName / getSessionPlanName / clearSessionPlanName
• index.ts — Barrel export for plan-name-tracker

Consumer hooks (all migrated to plan-aware calls):

• src/hooks/start-work/start-work-hook.ts — Primary writer; calls setSessionPlanName + writes to per-plan path
• src/hooks/atlas/event-handler.ts — Reads via getSessionPlanName → readBoulderState(dir, planName) ?? findBoulderForSession
• src/hooks/atlas/tool-execute-after.ts — Same fallback chain + appendSessionId with plan name
• src/hooks/prometheus-md-only/agent-resolution.ts — Uses findBoulderForSession for agent resolution
• src/cli/run/continuation-state.ts — Uses findBoulderForSession (disk-only; CLI is a separate process)
• src/plugin/tool-execute-before.ts — /stop-continuation clears per-plan boulder + clearSessionPlanName

Cleanup wiring:

• src/plugin/event.ts — session.deleted now calls clearSessionPlanName(sessionID)
• src/features/builtin-commands/templates/start-work.ts — Updated path references from boulder.json to boulders/{plan-name}.json

Backward Compatibility

• All 5 storage functions accept optional planName? as last parameter — omitting it reads/writes the legacy .sisyphus/boulder.json path unchanged
• findBoulderForSession scans per-plan files first, then falls back to legacy boulder.json
• appendSessionId falls back to legacy path when the per-plan file doesn't exist
• Zero breaking changes to existing consumers that don't pass planName

Testing

• TDD approach: tests written RED → GREEN for all new storage functions
• 9 new tests in storage.test.ts covering per-plan read/write/clear/append/find + legacy fallback
• 5 new tests in plan-name-tracker.test.ts covering set/get/clear/reset
• All 31 storage tests pass; all 36 atlas hook tests pass; all 107 targeted tests pass
• Full suite: 3299 pass (52 pre-existing failures unchanged — none related to this change)

Summary by cubic

Enable concurrent plan execution by moving boulder state to per-plan files and adding a session→plan tracker. All hooks now resolve plan-aware state with a legacy fallback; no breaking changes.

• New Features

  • Per-plan storage at .sisyphus/boulders/{plan}.json; all read/write/append/clear functions accept optional planName.
  • New findBoulderForSession scans per-plan files first, then falls back to legacy boulder.json.
  • In-memory session→plan Map with set/get/clear; cleared on session.deleted and /stop-continuation.
  • Consumers updated: start-work writes per-plan and registers mapping; atlas handlers resolve via tracker or disk scan; CLI continuation uses findBoulderForSession; template paths updated.

• Migration

  • No changes required; legacy .sisyphus/boulder.json remains supported.
  • To opt into concurrency in custom code, pass planName to storage functions.

^{Written for commit b38fbb8. Summary will update on new commits.}