Add human escalation path with severity levels (gt-1z3z)

Implements structured escalation channel for Gas Town:
- gt escalate command with CRITICAL/HIGH/MEDIUM severity levels
- Mayor startup check for pending escalations
- Escalation beads with tag for audit trail
- Mail routing to overseer with priority mapping
- Documentation in docs/escalation.md

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

docs/escalation.md

@@ -0,0 +1,149 @@
+# Gas Town Escalation Protocol
+
+> Reference for human escalation path in Gas Town
+
+## Overview
+
+Gas Town agents can escalate issues to the human overseer when automated
+resolution isn't possible. This provides a structured channel for:
+
+- System-threatening errors (data corruption, security issues)
+- Unresolvable conflicts (merge conflicts, ambiguous requirements)
+- Design decisions requiring human judgment
+- Edge cases in molecular algebra that can't proceed without guidance
+
+## Severity Levels
+
+| Level | Priority | Description | Examples |
+|-------|----------|-------------|----------|
+| **CRITICAL** | P0 (urgent) | System-threatening, immediate attention | Data corruption, security breach, system down |
+| **HIGH** | P1 (high) | Important blocker, needs human soon | Unresolvable merge conflict, critical bug, ambiguous spec |
+| **MEDIUM** | P2 (normal) | Standard escalation, human at convenience | Design decision needed, unclear requirements |
+
+## Escalation Command
+
+Any agent can escalate directly using `gt escalate`:
+
+```bash
+# Basic escalation (default: MEDIUM severity)
+gt escalate "Database migration failed"
+
+# Critical escalation - immediate attention
+gt escalate -s CRITICAL "Data corruption detected in user table"
+
+# High priority escalation
+gt escalate -s HIGH "Merge conflict cannot be resolved automatically"
+
+# With additional details
+gt escalate -s MEDIUM "Need clarification on API design" -m "The spec mentions both REST and GraphQL..."
+```
+
+### What happens on escalation
+
+1. **Bead created**: An escalation bead (tagged `escalation`) is created for audit trail
+2. **Mail sent**: Mail is sent to the `overseer` (human operator) with appropriate priority
+3. **Activity logged**: Event logged to the activity feed for visibility
+
+## Escalation Flow
+
+```
+Any Agent                     Overseer (Human)
+    |                              |
+    | gt escalate -s HIGH "msg"    |
+    |----------------------------->|
+    |                              |
+    | [ESCALATION] msg (P1 mail)   |
+    |----------------------------->|
+    |                              |
+    |     Reviews & resolves       |
+    |                              |
+    |   bd close <esc-id>          |
+    |<-----------------------------|
+```
+
+## Mayor Startup Check
+
+On `gt prime`, the Mayor automatically checks for pending escalations:
+
+```
+## PENDING ESCALATIONS
+
+There are 3 escalation(s) awaiting human attention:
+
+  CRITICAL: 1
+  HIGH: 1
+  MEDIUM: 1
+
+  [CRITICAL] Data corruption detected (gt-abc)
+  [HIGH] Merge conflict in auth module (gt-def)
+  [MEDIUM] API design clarification needed (gt-ghi)
+
+**Action required:** Review escalations with `bd list --tag=escalation`
+Close resolved ones with `bd close <id> --reason "resolution"`
+```
+
+## When to Escalate
+
+### Agents SHOULD escalate when:
+
+- **System errors**: Database corruption, disk full, network failures
+- **Security issues**: Unauthorized access attempts, credential exposure
+- **Unresolvable conflicts**: Merge conflicts that can't be auto-resolved
+- **Ambiguous requirements**: Spec is unclear, multiple valid interpretations
+- **Design decisions**: Architectural choices that need human judgment
+- **Stuck loops**: Agent is stuck and can't make progress
+
+### Agents should NOT escalate for:
+
+- **Normal workflow**: Regular work that can proceed without human input
+- **Recoverable errors**: Transient failures that will auto-retry
+- **Information queries**: Questions that can be answered from context
+
+## Molecular Algebra Edge Cases
+
+All edge cases in molecular algebra should escalate rather than fail silently:
+
+```go
+// Example: Molecule step has conflicting dependencies
+if hasConflictingDeps {
+    // Don't fail silently - escalate
+    exec.Command("gt", "escalate", "-s", "HIGH",
+        "Molecule step has conflicting dependencies: "+stepID).Run()
+}
+```
+
+This ensures:
+1. Issues are visible to humans
+2. Audit trail exists for debugging
+3. System doesn't silently break
+
+## Viewing Escalations
+
+```bash
+# List all open escalations
+bd list --status=open --tag=escalation
+
+# View specific escalation
+bd show <escalation-id>
+
+# Close resolved escalation
+bd close <id> --reason "Resolved by fixing X"
+```
+
+## Integration with Existing Flow
+
+The escalation system integrates with the existing polecat exit flow:
+
+| Exit Type | When to Use | Escalation? |
+|-----------|-------------|-------------|
+| `COMPLETED` | Work done successfully | No |
+| `ESCALATED` | Hit blocker, needs human | Yes (automatic via `gt done --exit ESCALATED`) |
+| `DEFERRED` | Work paused, will resume | No |
+
+When a polecat uses `gt done --exit ESCALATED`:
+1. Witness receives the notification
+2. Witness can forward to Mayor with `ESCALATION:` subject
+3. Mayor callback handler forwards to overseer
+
+The new `gt escalate` command provides a more direct path that any agent can use,
+with structured severity levels and audit trail.

docs/reference.md

@@ -222,6 +222,16 @@ gt mail send <addr> -s "Subject" -m "Body"
 gt mail send --human -s "..."    # To overseer
 ```
 
+### Escalation
+```bash
+gt escalate "topic"              # Default: MEDIUM severity
+gt escalate -s CRITICAL "msg"    # Urgent, immediate attention
+gt escalate -s HIGH "msg"        # Important blocker
+gt escalate -s MEDIUM "msg" -m "Details..."
+```
+
+See [escalation.md](escalation.md) for full protocol.
+
 ### Sessions
 ```bash
 gt handoff                   # Request cycle (context-aware)