feat: implement priming subsystem improvements

Phase 1 of dynamic priming subsystem:

1. PRIME.md provisioning for all workers (hq-5z76w, hq-ukjrr Part A)
   - Added ProvisionPrimeMD to beads package with Gas Town context template
   - Provision at rig level in AddRig() so all workers inherit it
   - Added fallback provisioning in crew and polecat managers
   - Created PRIME.md for existing rigs

2. Post-handoff detection to prevent handoff loop bug (hq-ukjrr Part B)
   - Added FileHandoffMarker constant (.runtime/handoff_to_successor)
   - gt handoff writes marker before respawn
   - gt prime detects marker and outputs "HANDOFF COMPLETE" warning
   - Marker cleared after detection to prevent duplicate warnings

3. Priming health checks for gt doctor (hq-5scnt)
   - New priming_check.go validates priming subsystem configuration
   - Checks: SessionStart hook, gt prime command, PRIME.md presence
   - Warns if CLAUDE.md is too large (should be bootstrap pointer)
   - Fixable: provisions missing PRIME.md files

This ensures crew workers get Gas Town context (GUPP, hooks, propulsion)
even if the gt prime hook fails, via bd prime fallback.

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

internal/cmd/doctor.go

@@ -161,6 +161,9 @@ func runDoctor(cmd *cobra.Command, args []string) error {
 	d.Register(doctor.NewLegacyGastownCheck())
 	d.Register(doctor.NewClaudeSettingsCheck())
 
+	// Priming subsystem check
+	d.Register(doctor.NewPrimingCheck())
+
 	// Crew workspace checks
 	d.Register(doctor.NewCrewStateCheck())
 	d.Register(doctor.NewCrewWorktreeCheck())

internal/cmd/handoff.go

@@ -9,6 +9,7 @@ import (
 
 	"github.com/spf13/cobra"
 	"github.com/steveyegge/gastown/internal/config"
+	"github.com/steveyegge/gastown/internal/constants"
 	"github.com/steveyegge/gastown/internal/events"
 	"github.com/steveyegge/gastown/internal/session"
 	"github.com/steveyegge/gastown/internal/style"
@@ -192,6 +193,16 @@ func runHandoff(cmd *cobra.Command, args []string) error {
 		style.PrintWarning("could not clear history: %v", err)
 	}
 
+	// Write handoff marker for successor detection (prevents handoff loop bug).
+	// The marker is cleared by gt prime after it outputs the warning.
+	// This tells the new session "you're post-handoff, don't re-run /handoff"
+	if cwd, err := os.Getwd(); err == nil {
+		runtimeDir := filepath.Join(cwd, constants.DirRuntime)
+		_ = os.MkdirAll(runtimeDir, 0755)
+		markerPath := filepath.Join(runtimeDir, constants.FileHandoffMarker)
+		_ = os.WriteFile(markerPath, []byte(currentSession), 0644)
+	}
+
 	// Use exec to respawn the pane - this kills us and restarts
 	return t.RespawnPane(pane, restartCmd)
 }

internal/cmd/prime.go

@@ -83,10 +83,6 @@ func init() {
 type RoleContext = RoleInfo
 
 func runPrime(cmd *cobra.Command, args []string) error {
-	if !state.IsEnabled() {
-		return nil
-	}
-
 	cwd, err := os.Getwd()
 	if err != nil {
 		return fmt.Errorf("getting current directory: %w", err)
@@ -96,7 +92,17 @@ func runPrime(cmd *cobra.Command, args []string) error {
 	if err != nil {
 		return fmt.Errorf("finding workspace: %w", err)
 	}
+
+	// "Discover, Don't Track" principle:
+	// - If we're in a workspace, proceed - the workspace's existence IS the enable signal
+	// - If we're NOT in a workspace, check the global enabled state
+	// This ensures a missing/stale state file doesn't break workspace users
 	if townRoot == "" {
+		// Not in a workspace - check global enabled state
+		// (This matters for hooks that might run from random directories)
+		if !state.IsEnabled() {
+			return nil // Silent exit - not in workspace and not enabled
+		}
 		return fmt.Errorf("not in a Gas Town workspace")
 	}
 
@@ -117,6 +123,9 @@ func runPrime(cmd *cobra.Command, args []string) error {
 		}
 	}
 
+	// Check for handoff marker (prevents handoff loop bug)
+	checkHandoffMarker(cwd)
+
 	// Get role using env-aware detection
 	roleInfo, err := GetRoleWithContext(cwd, townRoot)
 	if err != nil {
@@ -1632,3 +1641,38 @@ func readSessionFile(dir string) string {
 	}
 	return ""
 }
+
+// checkHandoffMarker checks for a handoff marker file and outputs a warning if found.
+// This prevents the "handoff loop" bug where a new session sees /handoff in context
+// and incorrectly runs it again. The marker tells the new session: "handoff is DONE,
+// the /handoff you see in context was from YOUR PREDECESSOR, not a request for you."
+func checkHandoffMarker(workDir string) {
+	markerPath := filepath.Join(workDir, constants.DirRuntime, constants.FileHandoffMarker)
+	data, err := os.ReadFile(markerPath)
+	if err != nil {
+		// No marker = not post-handoff, normal startup
+		return
+	}
+
+	// Marker found - this is a post-handoff session
+	prevSession := strings.TrimSpace(string(data))
+
+	// Remove the marker FIRST so we don't warn twice
+	_ = os.Remove(markerPath)
+
+	// Output prominent warning
+	fmt.Println()
+	fmt.Println(style.Bold.Render("╔══════════════════════════════════════════════════════════════════╗"))
+	fmt.Println(style.Bold.Render("║  ✅ HANDOFF COMPLETE - You are the NEW session                   ║"))
+	fmt.Println(style.Bold.Render("╚══════════════════════════════════════════════════════════════════╝"))
+	fmt.Println()
+	if prevSession != "" {
+		fmt.Printf("Your predecessor (%s) handed off to you.\n", prevSession)
+	}
+	fmt.Println()
+	fmt.Println(style.Bold.Render("⚠️  DO NOT run /handoff - that was your predecessor's action."))
+	fmt.Println("   The /handoff you see in context is NOT a request for you.")
+	fmt.Println()
+	fmt.Println("Instead: Check your hook (`gt mol status`) and mail (`gt mail inbox`).")
+	fmt.Println()
+}