feat(daemon): unify auto-sync config for simpler agent workflows (#904)

* feat(daemon): unify auto-sync config for simpler agent workflows

## Problem

Agents running `bd sync` at session end caused delays in the Claude Code
"event loop", slowing development. The daemon was already auto-exporting
DB→JSONL instantly, but auto-commit and auto-push weren't enabled by
default when sync-branch was configured - requiring manual `bd sync`.

Additionally, having three separate config options (auto-commit, auto-push,
auto-pull) was confusing and could get out of sync.

## Solution

Simplify to two intuitive sync modes:

1. **Read/Write Mode** (`daemon.auto-sync: true` or `BEADS_AUTO_SYNC=true`)
   - Enables auto-commit + auto-push + auto-pull
   - Full bidirectional sync - eliminates need for manual `bd sync`
   - Default when sync-branch is configured

2. **Read-Only Mode** (`daemon.auto-pull: true` or `BEADS_AUTO_PULL=true`)
   - Only receives updates from team
   - Does NOT auto-publish changes
   - Useful for experimental work or manual review before sharing

## Benefits

- **Faster agent workflows**: No more `bd sync` delays at session end
- **Simpler config**: Two modes instead of three separate toggles
- **Backward compatible**: Legacy auto_commit/auto_push settings still work
  (treated as auto-sync=true)
- **Adaptive `bd prime`**: Session close protocol adapts when daemon is
  auto-syncing (shows simplified 4-step git workflow, no `bd sync`)
- **Doctor warnings**: `bd doctor` warns about deprecated legacy config

## Changes

- cmd/bd/daemon.go: Add loadDaemonAutoSettings() with unified config logic
- cmd/bd/doctor.go: Add CheckLegacyDaemonConfig call
- cmd/bd/doctor/daemon.go: Add CheckDaemonAutoSync, CheckLegacyDaemonConfig
- cmd/bd/init_team.go: Use daemon.auto-sync in team wizard
- cmd/bd/prime.go: Detect daemon auto-sync, adapt session close protocol
- cmd/bd/prime_test.go: Add stubIsDaemonAutoSyncing for testing

* docs: add comprehensive daemon technical analysis

Add daemon-summary.md documenting the beads daemon architecture,
memory analysis (explaining the 30-35MB footprint), platform support
comparison, historical problems and fixes, and architectural guidance
for other projects implementing similar daemon patterns.

Key sections:
- Architecture deep dive with component diagrams
- Memory breakdown (SQLite WASM runtime is the main contributor)
- Platform support matrix (macOS/Linux full, Windows partial)
- Historical bugs and their fixes with reusable patterns
- Analysis of daemon usefulness without database (verdict: low value)
- Expert-reviewed improvement proposals (3 recommended, 3 skipped)
- Technical design patterns for other implementations

* feat: add cross-platform CI matrix and dual-mode test framework

Cross-Platform CI:
- Add Windows, macOS, Linux matrix to catch platform-specific bugs
- Linux: full tests with race detector and coverage
- macOS: full tests with race detector
- Windows: full tests without race detector (performance)
- Catches bugs like GH#880 (macOS path casing) and GH#387 (Windows daemon)

Dual-Mode Test Framework (cmd/bd/dual_mode_test.go):
- Runs tests in both direct mode and daemon mode
- Prevents recurring bug pattern (GH#719, GH#751, bd-fu83)
- Provides DualModeTestEnv with helper methods for common operations
- Includes 5 example tests demonstrating the pattern

Documentation:
- Add dual-mode testing section to CONTRIBUTING.md
- Document RunDualModeTest API and available helpers

Test Fixes:
- Fix sync_local_only_test.go gitPull/gitPush calls
- Add gate_no_daemon_test.go for beads-70c4 investigation

* fix(test): isolate TestFindBeadsDir tests with BEADS_DIR env var

The tests were finding the real project's .beads directory instead of
the temp directory because FindBeadsDir() walks up the directory tree.
Using BEADS_DIR env var provides proper test isolation.

* fix(test): stop daemon before running test suite guard

The test suite guard checks that tests don't modify the real repo's .beads
directory. However, a background daemon running auto-sync would touch
issues.jsonl during test execution, causing false positives.

Changes:
- Set BEADS_NO_DAEMON=1 to prevent daemon auto-start from tests
- Stop any running daemon for the repo before taking the "before" snapshot
- Uses exec to call `bd daemon --stop` to avoid import cycle issues

* chore: revert .beads/issues.jsonl to upstream/main

Per CONTRIBUTING.md, .beads/issues.jsonl should not be modified in PRs.

cmd/bd/doctor/daemon_test.go

@@ -1,12 +1,14 @@
 package doctor
 
 import (
+	"context"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"testing"
 
 	"github.com/steveyegge/beads/internal/git"
+	"github.com/steveyegge/beads/internal/storage/sqlite"
 )
 
 func TestCheckDaemonStatus(t *testing.T) {
@@ -79,7 +81,7 @@ func TestCheckGitSyncSetup(t *testing.T) {
 		}()
 
 		// Initialize git repo
-		cmd := exec.Command("git", "init")
+		cmd := exec.Command("git", "init", "--initial-branch=main")
 		cmd.Dir = tmpDir
 		if err := cmd.Run(); err != nil {
 			t.Fatalf("Failed to init git repo: %v", err)
@@ -104,3 +106,88 @@ func TestCheckGitSyncSetup(t *testing.T) {
 		}
 	})
 }
+
+func TestCheckDaemonAutoSync(t *testing.T) {
+	t.Run("no daemon socket", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		beadsDir := filepath.Join(tmpDir, ".beads")
+		if err := os.Mkdir(beadsDir, 0755); err != nil {
+			t.Fatal(err)
+		}
+
+		check := CheckDaemonAutoSync(tmpDir)
+
+		if check.Status != StatusOK {
+			t.Errorf("Status = %q, want %q", check.Status, StatusOK)
+		}
+		if check.Message != "Daemon not running (will use defaults on next start)" {
+			t.Errorf("Message = %q, want 'Daemon not running...'", check.Message)
+		}
+	})
+
+	t.Run("no sync-branch configured", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		beadsDir := filepath.Join(tmpDir, ".beads")
+		if err := os.Mkdir(beadsDir, 0755); err != nil {
+			t.Fatal(err)
+		}
+
+		// Create database without sync-branch config
+		dbPath := filepath.Join(beadsDir, "beads.db")
+		ctx := context.Background()
+		store, err := sqlite.New(ctx, dbPath)
+		if err != nil {
+			t.Fatal(err)
+		}
+		defer func() { _ = store.Close() }()
+
+		// Create a fake socket file to simulate daemon running
+		socketPath := filepath.Join(beadsDir, "bd.sock")
+		if err := os.WriteFile(socketPath, []byte{}, 0600); err != nil {
+			t.Fatal(err)
+		}
+
+		check := CheckDaemonAutoSync(tmpDir)
+
+		// Should return OK because no sync-branch means auto-sync not applicable
+		if check.Status != StatusOK {
+			t.Errorf("Status = %q, want %q", check.Status, StatusOK)
+		}
+		if check.Message != "No sync-branch configured (auto-sync not applicable)" {
+			t.Errorf("Message = %q, want 'No sync-branch...'", check.Message)
+		}
+	})
+
+	t.Run("sync-branch configured but cannot connect", func(t *testing.T) {
+		tmpDir := t.TempDir()
+		beadsDir := filepath.Join(tmpDir, ".beads")
+		if err := os.Mkdir(beadsDir, 0755); err != nil {
+			t.Fatal(err)
+		}
+
+		// Create database with sync-branch config
+		dbPath := filepath.Join(beadsDir, "beads.db")
+		ctx := context.Background()
+		store, err := sqlite.New(ctx, dbPath)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := store.SetConfig(ctx, "sync.branch", "beads-sync"); err != nil {
+			t.Fatal(err)
+		}
+		_ = store.Close()
+
+		// Create a fake socket file (not a real daemon)
+		socketPath := filepath.Join(beadsDir, "bd.sock")
+		if err := os.WriteFile(socketPath, []byte{}, 0600); err != nil {
+			t.Fatal(err)
+		}
+
+		check := CheckDaemonAutoSync(tmpDir)
+
+		// Should return warning because can't connect to fake socket
+		if check.Status != StatusWarning {
+			t.Errorf("Status = %q, want %q", check.Status, StatusWarning)
+		}
+	})
+}