docs(01-01): complete scaffolding + process detection plan

- SUMMARY.md with execution results
- STATE.md advanced to plan 2/2
- ROADMAP.md and REQUIREMENTS.md updated (DISC-01, DISC-02 complete)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.planning/phases/01-session-discovery/01-01-SUMMARY.md

@@ -0,0 +1,91 @@
+---
+phase: 01-session-discovery
+plan: 01
+subsystem: process-detection
+tags: [go, proc, linux, cli]
+
+requires: []
+provides:
+  - "Go module scaffold (shell.nix, go.mod)"
+  - "Shared types: Process, Session, SessionState"
+  - "FindClaudeProcesses() scanning /proc for Claude PIDs"
+  - "EncodePath() converting absolute paths to ~/.claude/projects/ folder names"
+affects: [01-02, 02-session-state]
+
+tech-stack:
+  added: [go-1.25, go-stdlib-os]
+  patterns: [injectable-procdir-for-testing, fake-proc-fixtures]
+
+key-files:
+  created: [shell.nix, go.mod, types.go, proc.go, proc_test.go]
+  modified: []
+
+key-decisions:
+  - "filepath.Base matching for Claude binary detection (handles full paths)"
+  - "procDir parameter injection for testability (no hardcoded /proc)"
+
+patterns-established:
+  - "Fake /proc fixtures: createFakeProc() builds temp dirs with cmdline files and cwd symlinks"
+  - "Silent error skipping: permission denied and vanished processes are skipped, not fatal"
+
+requirements-completed: [DISC-01, DISC-02]
+
+duration: 2min
+completed: 2026-03-23
+---
+
+# Phase 01 Plan 01: Scaffolding + Process Detection Summary
+
+**Go module with FindClaudeProcesses() scanning /proc for active Claude Code PIDs and EncodePath() for session folder mapping**
+
+## Performance
+
+- **Duration:** 2 min
+- **Started:** 2026-03-23T12:23:44Z
+- **Completed:** 2026-03-23T12:25:44Z
+- **Tasks:** 2
+- **Files created:** 5
+
+## Accomplishments
+- Go project scaffolded with NixOS shell.nix, go.mod, and shared types (Process, Session, SessionState)
+- FindClaudeProcesses() scans configurable /proc directory, filters by "claude" binary name, reads cwd via Readlink
+- EncodePath() converts paths to ~/.claude/projects/ folder format (replace / and . with -)
+- 5 tests covering normal detection, permission denied, empty proc, and path encoding edge cases
+
+## Task Commits
+
+Each task was committed atomically:
+
+1. **Task 1: Scaffolding projet + types partages** - `12e1ba7` (feat)
+2. **Task 2 RED: Failing tests for proc scanning** - `81ee7dc` (test)
+3. **Task 2 GREEN: Implement FindClaudeProcesses and EncodePath** - `166e441` (feat)
+
+## Files Created/Modified
+- `shell.nix` - NixOS dev environment with go and gopls
+- `go.mod` - Go module github.com/pieMusic/vmux
+- `types.go` - Shared types: Process, Session, SessionState (Working/NeedsInput/Idle/Unknown)
+- `proc.go` - FindClaudeProcesses() and EncodePath()
+- `proc_test.go` - 5 unit tests with fake /proc fixtures
+
+## Decisions Made
+- Used `filepath.Base(parts[0])` for binary detection to handle full paths like `/nix/store/.../claude`
+- Injected procDir as parameter for full testability without mocking os functions
+
+## Deviations from Plan
+
+None - plan executed exactly as written.
+
+## Issues Encountered
+- shell.nix was in Pierre's global gitignore; force-added with `git add -f` since it is project-specific
+
+## User Setup Required
+
+None - no external service configuration required.
+
+## Next Phase Readiness
+- Types and process detection ready for plan 01-02 (JSONL session matching, state heuristics, display)
+- EncodePath enables PID-to-session folder mapping
+
+---
+*Phase: 01-session-discovery*
+*Completed: 2026-03-23*