Hook system for event extensibility

GGT needs hook system for extensibility like PGT.

## Event Types
```go
type Event string
const (
    EventPreSessionStart  Event = "pre-session-start"
    EventPostSessionStart Event = "post-session-start"
    EventPreShutdown      Event = "pre-shutdown"
    EventPostShutdown     Event = "post-shutdown"
    EventOnPaneOutput     Event = "on-pane-output"
    EventSessionIdle      Event = "session-idle"
    EventMailReceived     Event = "mail-received"
    EventWorkAssigned     Event = "work-assigned"
)
```

## Hook Configuration
File: .claude/hooks.json or .gastown/hooks.json
```json
{
  "hooks": {
    "pre-shutdown": [
      {"type": "command", "cmd": "./scripts/pre-shutdown.sh"}
    ],
    "on-pane-output": [
      {"type": "command", "cmd": "./scripts/activity-monitor.sh"}
    ]
  }
}
```

## Hook Types
1. **Command**: Execute external script
2. **Built-in**: Internal Go functions (pre-shutdown checks)

## Hook Interface
```go
type HookRunner struct {
    config *HookConfig
}

type HookResult struct {
    Success bool
    Message string
    Block   bool  // For pre-* hooks: should operation be blocked?
}

func (r *HookRunner) Fire(event Event, ctx *HookContext) []HookResult
```

## CLI Commands
```
gt hooks list [<event>]    # List registered hooks
gt hooks fire <event>      # Manually fire for testing
gt hooks test [--all]      # Validate hook config
```

## Integration Points
- internal/session/manager.go: Fire pre/post session hooks
- internal/mail/router.go: Fire mail-received hook

## New Package
internal/hooks/
├── types.go    # Event, HookConfig, HookResult
├── runner.go   # HookRunner, Fire()
└── builtin.go  # Built-in hooks (pre-shutdown checks)

## PGT Reference
gastown-py/src/gastown/hooks/

## Acceptance Criteria
- [ ] Hook config loading from JSON
- [ ] Command hooks execute subprocess
- [ ] Pre-shutdown hook integration with session stop
- [ ] CLI for listing and testing hooks


Add 'wit' alias for witness command

ref works as alias for refinery, but wit doesn't work for witness. Add Aliases: []string{"wit"} to witnessCmd.


Merge: gt-rana.4

branch: polecat/ace
target: main
source_issue: gt-rana.4
rig: gastown


Swarm learning: Session cleanup missing from swarm workflow

## Problem

After Enders Game swarm completed (18 issues merged), 16 polecat sessions were left running but idle. No automated cleanup occurred.

## What Should Happen

1. Witness detects polecat completed work (idle at prompt)
2. Witness verifies git state is clean
3. Witness shuts down session
4. Witness reports completion to Mayor

## GGT Components

- gt-cxx: Witness context cycling (covers self-cycling)
- gt-u1j.9: Witness daemon heartbeat loop
- gt-kmn.6: Witness swarm landing protocol

## Recommendation

Add to Witness responsibilities:
- Monitor for 'work complete' signals (DONE keyword, idle detection)
- Automated session shutdown after verification
- Swarm completion reporting to Mayor

See also: architecture.md 'Worker Cleanup (Witness-Owned)' section which describes this but it wasn't implemented in PGT.


Crew workers: design documentation and remaining work

## Summary

Crew workers are user-managed persistent workspaces within a rig, distinct from polecats.

## Current Implementation

### Commands (all working)
- `gt crew add <name>` - Create workspace (git clone)
- `gt crew list` - List workspaces with status
- `gt crew at <name>` - Attach to tmux session
- `gt crew remove <name>` - Remove workspace
- `gt crew pristine [<name>]` - git pull + bd sync
- `gt crew refresh <name>` - Context cycle with handoff mail
- `gt crew status [<name>]` - Detailed status
- `gt crew rename <name>` - Rename workspace

### Crew vs Polecat

| Aspect | Crew | Polecat |
|--------|------|---------|
| Lifecycle | User-managed | Witness-managed |
| Scheduling | Manual | `gt spawn` |
| Merge flow | Direct push OK | Integration branch → refinery |
| Garbage collection | Never | Auto on completion |
| Identity | Long-lived (emma, dave) | Ephemeral (Nux, Toast) |

## Known Bugs

- **gt-70b3**: detectSender() doesn't recognize crew workers
- **gt-vdp0**: Crew CLAUDE.md shows Refinery template

## Potential Enhancements

1. Rebase helper in `gt crew pristine` for conflict resolution
2. Cross-rig crew support (crew worker in multiple rigs?)
3. Better mail identity auto-detection for crew


load-context

Run gt prime and bd prime. Verify issue assignment.
Check inbox for any relevant messages.

Read the assigned issue ({{issue}}) and understand the requirements.
Identify any blockers or missing information.


Add harness overview to Mayor priming

Update gt prime Mayor context to explain the harness concept: umbrella repo for GT installation, rigs underneath, Mayor sits above all rigs


Configuration in Beads: use pinned beads for rig/agent config

## Summary

Move configuration from JSON files into Beads data plane using pinned beads.

## Motivation

- Config becomes versionable and syncable like issues
- Agents can read config via `bd show`
- Unified data model for everything
- Supports the 'Beads as Universal Data Plane' vision (gt-aqm)

## Config Types to Migrate

### Rig-level (pinned per rig)
- Theme/colors for tmux status line
- Default branch naming conventions
- Merge queue settings
- Witness thresholds

### Agent-level (pinned per role)
- Handoffs (already planned - gt-cu7r)
- Agent preferences
- Current focus/context

### Town-level (pinned at town root)
- Cross-rig settings
- Federation config
- Global themes

## Implementation

1. Implement StatusPinned (beads-6v2) ✓ in progress
2. Create config pinned beads on rig init
3. Add `bd config get/set` commands that read/write pinned beads
4. Migrate existing config.json fields

## Naming Convention

```
<prefix>-cfg-<scope>
gt-cfg-theme      # gastown theme
bd-cfg-merge      # beads merge settings
gm-cfg-town       # town-level config
```

## Dependencies

- beads-6v2: Add StatusPinned to beads schema
- gm-w13: Pinned Beads epic


Success handling: close MR, close source issue, cleanup

Handle successful merge completion.

Steps:
1. Update MR with merge_commit SHA:
   bd update <id> --body='...\nmerge_commit: <sha>'
2. Close MR with reason:
   bd close <id> --reason='merged'
3. Close source issue (the work item):
   bd close <source_issue> --reason='Merged in <mr_id>'
4. Delete source branch (if configured):
   git push origin --delete <mr.branch>
5. Log success

Configuration:
- delete_merged_branches: bool (default true)

Reference: docs/merge-queue-design.md#process-merge-steps


Digest: mol-deacon-patrol

Old test patrol cycle - cleanup


Preflight molecule: verify baseline health before work

Before assigning work, verify baseline (main branch) is healthy.

**From VC**: Self-healing state machine (HEALTHY → SELF_HEALING → ESCALATED). ~200 lines.

**Gas Town implementation**: Preflight molecule or refinery feature:
```yaml
preflight:
  gates: [test, lint, build]
  on_failure: create-fix-issue
```

Run at session start. If baseline broken, file a P0 fix issue and work on that first.

**Value**: Self-healing baseline. Agents don't start from broken state.

**VC lesson**: Prevents cascading failures. Agent shouldn't start work on broken code.


gt session restart/status: Complete session management

Add missing session subcommands:

- gt session restart <rig> <polecat> - Restart a session (stop + start)
- gt session status <rig> <polecat> - Show session status details

status should show:
- Running state
- Uptime
- Current activity
- Last output timestamp


Test2

Testing gt mail


Merge: gt-99a

branch: polecat/Slit
target: main
source_issue: gt-99a
rig: gastown


gt doctor: detect orphaned code on beads-sync branch

After merging beads-sync to main, some code changes can be lost if the merge conflict resolution drops files.

Add a doctor check that runs:
  git diff main..beads-sync -- '*.go' '*.md'

If there are differences in code files (not just .beads/), warn about potentially orphaned work.

Today's incident: Merge 96c773f lost mailbox.go and router.go changes from 5791752, requiring re-implementation.

Acceptance:
- gt doctor warns if beads-sync has unmerged code changes
- Excludes .beads/ directory (expected to differ)
- Shows file list of orphaned changes


orphan-check

Find abandoned work. Check for in_progress issues with no active agent.


Plugin surface for daemon lifecycle hooks

Allow rigs to customize daemon behavior via hooks/plugins.

## Hook Points

- on_heartbeat: Called during daemon heartbeat cycle
- on_worker_idle: Called when worker goes idle
- on_worker_stuck: Called when stuck detection triggers
- on_lifecycle_request: Called before processing lifecycle

## Configuration

```
<rig>/config/daemon-hooks.json
{
  "on_heartbeat": "./hooks/check-ci-status.sh",
  "on_worker_idle": "./hooks/maybe-assign-work.sh",
  "idle_threshold": "5m",
  "custom_signals": [
    {"name": "ci_status", "command": "./hooks/get-ci.sh"}
  ]
}
```

## Signal Contribution

Hooks can return signals that feed into decision engine:
- SKIP_POKE: Don't poke this agent
- FORCE_POKE: Override backoff, poke now
- CUSTOM_DATA: Extra context for logging

## Use Cases

- Check CI status before interrupting test runs
- Auto-assign work when worker becomes idle
- Custom stuck detection for specific workflows


Extended addressing: Parse [machine:]rig/polecat

Extended addressing for cross-machine operations.

## Address Format

```
[machine:]rig/polecat
```

Examples:
- `wyvern/Toast` - Local machine, wyvern rig, Toast polecat
- `gcp-vm-1:wyvern/Toast` - Remote machine
- `wyvern/` - Broadcast to rig
- `gcp-vm-1:wyvern/` - Broadcast to remote rig

## Parser

```go
type Address struct {
    Machine  string  // empty = local
    Rig      string
    Polecat  string  // empty = broadcast
}

func ParseAddress(s string) (*Address, error)
func (a *Address) String() string
func (a *Address) IsLocal() bool
func (a *Address) IsBroadcast() bool
```

## Validation

```go
func (a *Address) Validate(registry *MachineRegistry) error
```
- Machine must exist in registry (if specified)
- Rig must exist on machine
- Polecat must exist (if specified)

## Usage

All CLI commands that take addresses use ParseAddress:
```go
// gt mail send gcp-vm-1:wyvern/Toast -s "Hello"
addr, _ := ParseAddress("gcp-vm-1:wyvern/Toast")
conn, _ := registry.Connection(addr.Machine)
// Use conn for operations
```

## Backward Compatibility

Existing `rig/polecat` addresses work unchanged (Machine defaults to local).