Consolidate configuration architecture: three-tier model

Rationalize Gas Town's scattered configuration into a clean three-tier model:

## Current Problems
- Config split across mayor/, .gastown/, and rig/config.json
- Runtime state mixed with configuration
- Hidden directories (.gastown/) are missed by agents
- Category confusion: identity vs config vs runtime state

## Proposed Architecture

### Tier 1: Town Config (mayor/)
```
mayor/
├── town.json      # Town identity (unchanged)
├── rigs.json      # Rig registry (unchanged)
└── config.json    # NEW: Town-level configuration
    # theme defaults, daemon settings, etc.
```

### Tier 2: Town Runtime (.runtime/)
```
~/gt/.runtime/                    # NEW: Gitignored
├── daemon.json                   # {pid, started_at, heartbeat}
├── deacon.json                   # {cycle, last_action}
└── agent-requests.json           # Lifecycle requests
```

### Tier 3: Rig Config (settings/)
```
<rig>/
├── config.json                   # Rig identity only (type, git_url, beads.prefix)
├── settings/                     # NEW: Visible, git-tracked
│   ├── config.json               # theme, merge_queue, max_workers
│   ├── namepool.json             # pool settings (style, max)
│   └── roles/                    # Per-role overrides (optional)
└── .runtime/                     # NEW: Gitignored
    ├── witness.json              # {state, started_at, stats}
    ├── refinery.json             # {state, started_at, stats}
    └── namepool-state.json       # {in_use, overflow_next}
```

## Key Principles
1. **Visible > Hidden** for config agents need to find
2. **Git-tracked** for identity and config; **gitignored** for runtime
3. **Separation of concerns**: identity, config, runtime are distinct
4. **Locality**: town config at town root, rig config at rig root

## Migration
- Move .gastown/ contents to appropriate new locations
- Update all code that reads/writes these files
- Update .gitignore patterns
- Update documentation (architecture.md, CLAUDE.md)


Phase 2.1: gt spawn --molecule bonds in ephemeral

Make gt spawn molecule-aware with ephemeral bonding.

## New Flag

```bash
gt spawn --issue gt-xxx --molecule mol-polecat-work
```

## Behavior

1. Create polecat with fresh worktree (existing)
2. Bond molecule in ephemeral: `bd mol bond mol-polecat-work --ephemeral`
3. Link molecule root to source issue
4. Include molecule context in work assignment mail
5. Start session

## Work Assignment Mail

```
Subject: Work Assignment: Fix lifecycle bug [MOLECULE]

You are working on gt-rixa as part of molecule mol-polecat-work.

Molecule instance: eph-abc123
Current step: read-assignment (1/8)

Follow the molecule workflow. When complete, generate summary and squash.
```


Complete gt crew commands (list, attach, remove, refresh, status)

Add remaining crew subcommands to internal/cmd/crew.go:

1. gt crew list - List crew workspaces with status
2. gt crew at/attach - Start tmux session in crew workspace
3. gt crew remove - Remove crew workspace (with safety checks)
4. gt crew refresh - Context cycling with mail-to-self handoff
5. gt crew status - Show detailed workspace status

Build on existing crew add implementation in internal/cmd/crew.go.
Reference closed issues gt-cik.3-7 for original requirements.


MR field parsing: extract structured fields from description

Parse merge-request beads to extract structured fields:
- branch: source branch name
- target: target branch (main or integration/xxx)
- source_issue: the work item being merged
- worker: who did the work
- rig: which rig
- merge_commit: (set on close)
- close_reason: (set on close)

Fields stored in description as YAML block or key: value lines.
Provide helper functions: ParseMRFields(issue) and SetMRFields(issue, fields).

Reference: docs/merge-queue-design.md#merge-request-schema


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.


Mail CLI: archive, purge, search, mark

GGT mail CLI needs more commands for mail management.

## Commands to Add

### gt mail check
Check for new mail without full inbox display.
```
gt mail check [--quiet] [--inject]
```
- --quiet: Only output if new mail (for scripts)
- --inject: Send notification to running session

### gt mail mark
Change read status.
```
gt mail mark <id> --read
gt mail mark <id> --unread
```

### gt mail delete
Remove message from inbox.
```
gt mail delete <id> [--force]
```
- Confirm unless --force

### gt mail archive
Move old/read messages to archive.
```
gt mail archive [--older-than DAYS] [--all-read] [--dry-run]
```
- Creates inbox.jsonl.archive or separate archive.jsonl

### gt mail purge
Permanently delete archived messages.
```
gt mail purge [--older-than DAYS] [--dry-run] [--force]
```

### gt mail search
Find messages by content.
```
gt mail search <query> [--from SENDER] [--subject] [--body]
```

### gt mail reply
Reply to a message.
```
gt mail reply <id> -m BODY
```
- Auto-sets reply_to and thread_id
- Auto-addresses to original sender

## Files to Modify
- internal/cmd/mail.go: Add commands
- internal/mail/mailbox.go: Add Archive(), Search(), Delete()

## Acceptance Criteria
- [ ] All commands implemented
- [ ] Archive stores in separate file
- [ ] Search supports regex patterns
- [ ] Delete confirms by default


MQ metrics: pending count, processing time, success rate

Implement merge queue metrics collection.

Metrics to track:
- mq_pending_count: MRs waiting
- mq_processing_time: Time from submit to merge (histogram)
- mq_success_rate: Merges vs rejections
- mq_conflict_rate: How often conflicts occur
- mq_test_failure_rate: Test failures

Storage options:
- Simple: JSON file with rolling stats
- Advanced: Prometheus-compatible metrics endpoint

Display via:
- gt mq stats: summary statistics
- Dashboard widget (separate task)

Reference: docs/merge-queue-design.md#observability


Update gt doctor to check new config locations

Doctor should validate new structure:
- Check mayor/config.json exists and is valid
- Check settings/ exists for each rig
- Warn if old .gastown/ files still exist
- Offer --fix to migrate old locations to new


TODO: Detect cycles in molecule dependency graph

molecule.go:302 has a TODO to detect cycles in the dependency graph. Currently, cyclical dependencies could cause issues.


Create mol-gastown-polecat derived molecule

Create the standard Gas Town polecat workflow molecule.

## Molecule Definition
\`\`\`markdown
## Molecule: gastown-polecat
Full workflow for Gas Town polecats including binary installation.

Includes: mol-engineer-in-box

## Step: install-binary
After merge is submitted, rebuild and install the local gt binary.
This ensures the latest code is available to all local agents.

Run from the rig directory:
\`\`\`
go build -o gt ./cmd/gt
go install ./cmd/gt
\`\`\`

Needs: submit
\`\`\`

## Why This Molecule
Every polecat that pushes to main should also rebuild the binary.
This ensures the installed gt is always current with main.

## Implementation
1. Add to builtin_molecules.go (after Includes support lands)
2. Update SeedBuiltinMolecules
3. Run gt molecule seed

## Acceptance
- [ ] mol-gastown-polecat exists
- [ ] Includes all engineer-in-box steps
- [ ] Adds install-binary step after submit
- [ ] Can be used with gt spawn --molecule


gt crew status: Show workspace status

Implement 'gt crew status [<name>]' command:
- Show session state (running/stopped)
- Show git status (branch, uncommitted changes, unpushed)
- Show last commit info
- Show mail inbox status (unread count)
- If no name given, show all crew workers


Workspace detection: Find() walking up directory tree

Find workspace root by walking up directory tree looking for Gas Town markers.

## Detection Logic

Walk up from current directory, looking for:
1. `config/town.json` - Primary marker (visible config dir per gt-iib)
2. `mayor/` directory at town level - Secondary marker

Stop at filesystem root if neither found.

## Interface

```go
// Find locates the town root from the given directory
func Find(startDir string) (string, error)

// FindOrError is like Find but returns a user-friendly error
func FindOrError(startDir string) (string, error)
```

## Return Values

- Success: Absolute path to town root
- Not found: Empty string + specific error
- Error: Empty string + wrapped error

## Edge Cases

- Symlinks: Follow them (use filepath.EvalSymlinks)
- Permissions: Return error if can't read directory
- Nested towns: Return nearest ancestor (shouldn't happen in practice
EOF
)


bd ready --type: missing type filter for MQ integration

bd ready lacks --type flag that engineer.go expects.

## Code (internal/refinery/engineer.go)
readyMRs, err := e.beads.ReadyWithType("merge-request")

## Actual bd ready
No --type flag - only supports assignee, label, priority filters.

## Impact
Refinery can't find merge-requests in queue, so MQ doesn't process anything.

## Fix Options
1. Add --type flag to bd ready
2. Use bd list --type=merge-request --status=open instead
3. Both (ready filters for unblocked, list for all)

This is blocking the entire MQ pipeline.


Molecule format bridge: convert embedded markdown to child issues

## Problem

Two molecule formats exist:
1. **Old (gastown builtin)**: Steps embedded as markdown in Description field, parsed by ParseMoleculeSteps()
2. **New (bd mol)**: Steps as child issues in proper beads DAG

The daemon's InstantiateMolecule() uses the old format. bd mol spawn uses the new format.

## Options

### Option A: Require child issues (new format)
- Update daemon to use bd mol spawn instead of InstantiateMolecule
- Deprecate embedded markdown format
- Pro: One format, simpler
- Con: Breaking change for existing molecules

### Option B: Build a bridge
- In InstantiateMolecule, detect format:
  - If Description has ## Step: markers → parse to child issues
  - If issue has children with template label → use directly
- Convert old format to new format on instantiation
- Pro: Backward compatible
- Con: More complexity

## Recommendation

Option B - build the bridge. On instantiation, convert markdown steps to child issues. This unifies execution while preserving authoring flexibility.


test message


Update harness beads redirect for GGT

Change ~/ai/.beads/redirect from mayor/rigs/gastown/.beads to gastown/mayor/.beads for the GGT directory structure


orphan-check

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


Bug: LIFECYCLE messages use literal <rig> placeholder

Found stale LIFECYCLE messages addressed to @<rig>/witness instead of actual rig names like @gastown/witness. Template substitution not happening.

Examples found:
- gm-bay: LIFECYCLE: polecat requesting shutdown (to @<rig>/witness)
- gm-7du, gm-94e, gm-u5x, gm-89b: same issue

Fix: Ensure rig name is substituted in lifecycle mail templates.


Implement gt sling command

The unified work dispatch command.

```bash
gt sling <thing> <target> [options]
```

Implements spawn + assign + pin in one operation. See sling-design.md.

Acceptance:
- [ ] Parse thing (proto name, issue ID, epic ID)
- [ ] Parse target (agent address)
- [ ] Spawn molecule if proto
- [ ] Assign to target agent
- [ ] Pin to agent's hook (pinned bead)
- [ ] Support --wisp flag for ephemeral
- [ ] Support --molecule flag for issue+workflow
- [ ] Error if hook already occupied (unless --force)