Fix messages --sync behind live tail

CHANGELOG.md

@@ -24,6 +24,7 @@
 ### Fixes
 
 - Kept resumed `sync --full` backfills from moving channel latest-message checkpoints backward, avoiding duplicate head recrawls on large interrupted channels. Thanks @hannesrudolph.
+- Made `messages --sync` fail fast with an omit-`--sync` hint when a live `tail` process owns the sync lock, while plain `messages` reads continue without waiting. Thanks @jeanmonet.
 
 ## 0.9.1 - 2026-05-18
 

README.md

@@ -384,7 +384,7 @@ Notes:
 - `--days` is shorthand for "since now minus N days"
 - `--last` returns the newest `N` matching messages, then prints them oldest-to-newest
 - `--all` removes the safety limit; default is `200`
-- `--sync` runs a blocking pre-query sync for the matching channel or guild scope before reading the local DB
+- `--sync` runs a blocking pre-query sync for the matching channel or guild scope before reading the local DB; omit it while `tail` is already maintaining live freshness
 - rows with no displayable/searchable content are skipped by default; `--include-empty` opts back in
 - at least one filter is required
 - `--dm` is shorthand for `--guild @me`, so DM searches and message slices do not need raw SQL

docs/commands/messages.md

@@ -26,12 +26,13 @@ discrawl --json messages --channel maintainers --days 3
 - `--last <n>` - return the newest `N` matching messages, then print oldest-to-newest
 - `--limit <n>` - safety limit (default 200; `--all` removes it)
 - `--all` - removes the safety limit
-- `--sync` - blocking pre-query sync for the matching channel or guild scope
+- `--sync` - blocking pre-query sync for the matching channel or guild scope; omit while `tail` is already maintaining live freshness
 - `--include-empty` - include rows with no displayable/searchable content
 
 ## Notes
 
 - at least one filter is required
+- if `tail` is already running, plain `messages` reads the local archive without waiting; `messages --sync` fails fast instead of waiting behind the tail lock
 - `--dm` skips Git snapshot auto-update because DMs are never imported from the shared mirror
 - use either `--last` for the newest matching rows or `--all` for an uncapped oldest-to-newest slice
 

internal/cli/admin_commands.go

@@ -332,6 +332,12 @@ func (r *runtime) runTail(args []string) error {
 	}
 	ctx, stop := signal.NotifyContext(r.ctx, os.Interrupt, syscall.SIGTERM)
 	defer stop()
+	if configurable, ok := r.syncer.(tailReadyConfigurer); ok {
+		configurable.SetTailReadyCallback(func(context.Context) error {
+			return r.activateTailSyncLock()
+		})
+		defer configurable.SetTailReadyCallback(nil)
+	}
 	return r.syncer.RunTail(ctx, r.resolveSyncGuilds(*guildFlag, *guildsFlag), *repairEvery)
 }
 

internal/cli/cli.go

@@ -145,25 +145,28 @@ func parseKongArgs(target any, args []string, name string, stdout, stderr io.Wri
 }
 
 type runtime struct {
-	ctx         context.Context
-	configPath  string
-	cfg         config.Config
-	stdout      io.Writer
-	stderr      io.Writer
-	json        bool
-	plain       bool
-	logger      *slog.Logger
-	store       *store.Store
-	client      discordClient
-	syncer      syncService
-	dbLockHeld  bool
-	lockStarted time.Time
-	openStore   func(context.Context, string) (*store.Store, error)
-	newDiscord  func(config.Config) (discordClient, error)
-	newRemote   func(config.Config) (remoteArchiveClient, error)
-	newSyncer   func(syncer.Client, *store.Store, *slog.Logger) syncService
-	newEmbed    func(config.EmbeddingsConfig) (embed.Provider, error)
-	now         func() time.Time
+	ctx           context.Context
+	configPath    string
+	cfg           config.Config
+	stdout        io.Writer
+	stderr        io.Writer
+	json          bool
+	plain         bool
+	logger        *slog.Logger
+	store         *store.Store
+	client        discordClient
+	syncer        syncService
+	dbLockHeld    bool
+	lockStarted   time.Time
+	lockOperation string
+	lockToken     string
+	lockTokenFree func() error
+	openStore     func(context.Context, string) (*store.Store, error)
+	newDiscord    func(config.Config) (discordClient, error)
+	newRemote     func(config.Config) (remoteArchiveClient, error)
+	newSyncer     func(syncer.Client, *store.Store, *slog.Logger) syncService
+	newEmbed      func(config.EmbeddingsConfig) (embed.Provider, error)
+	now           func() time.Time
 }
 
 func crawlkitEmbeddingConfig(cfg config.EmbeddingsConfig) embed.Config {
@@ -190,6 +193,10 @@ type syncService interface {
 	RunTail(context.Context, []string, time.Duration) error
 }
 
+type tailReadyConfigurer interface {
+	SetTailReadyCallback(func(context.Context) error)
+}
+
 type attachmentTextConfigurer interface {
 	SetAttachmentTextEnabled(bool)
 }
@@ -209,7 +216,7 @@ func (r *runtime) dispatch(rest []string) error {
 		}
 		return r.withLocalStoreUpdateLocked(updateMode, true, func() error { return r.runSync(rest[1:]) })
 	case "tail":
-		return r.withServicesLocked(true, func() error { return r.runTail(rest[1:]) })
+		return r.withServicesLockedOperation(true, "tail-starting", func() error { return r.runTail(rest[1:]) })
 	case "wiretap":
 		return r.withLocalStoreLocked(false, func() error { return r.runWiretap(rest[1:]) })
 	case "tap", "cache-import":
@@ -235,10 +242,10 @@ func (r *runtime) dispatch(rest []string) error {
 		if r.configuredForCloudReadOnly() {
 			return r.withConfig(func() error { return r.runMessages(rest[1:]) })
 		}
-		if hasBoolFlag(rest[1:], "--sync") && !hasBoolFlag(rest[1:], "--dm") {
-			return r.withServicesAutoLocked(true, true, true, func() error { return r.runMessages(rest[1:]) })
+		if boolFlagEnabled(rest[1:], "--sync") && !boolFlagEnabled(rest[1:], "--dm") {
+			return r.withMessagesSyncServices(func() error { return r.runMessages(rest[1:]) })
 		}
-		autoShareUpdate := !hasBoolFlag(rest[1:], "--dm")
+		autoShareUpdate := !boolFlagEnabled(rest[1:], "--dm")
 		return r.withLocalStoreRead(autoShareUpdate, func() error { return r.runMessages(rest[1:]) })
 	case "digest":
 		return r.withLocalStoreRead(true, func() error { return r.runDigest(rest[1:]) })
@@ -323,8 +330,8 @@ func (r *runtime) withServices(withDiscord bool, fn func() error) error {
 	return r.withServicesAuto(withDiscord, !withDiscord, fn)
 }
 
-func (r *runtime) withServicesLocked(withDiscord bool, fn func() error) error {
-	return r.withServicesAutoLocked(withDiscord, !withDiscord, true, fn)
+func (r *runtime) withServicesLockedOperation(withDiscord bool, operation string, fn func() error) error {
+	return r.withServicesUpdateLockedOperation(withDiscord, boolShareUpdateMode(!withDiscord), true, operation, fn)
 }
 
 func (r *runtime) withLocalStoreLocked(autoShareUpdate bool, fn func() error) error {
@@ -541,10 +548,14 @@ func (r *runtime) withServicesAuto(withDiscord, autoShareUpdate bool, fn func()
 }
 
 func (r *runtime) withServicesAutoLocked(withDiscord, autoShareUpdate, lockDB bool, fn func() error) error {
-	return r.withServicesUpdateLocked(withDiscord, boolShareUpdateMode(autoShareUpdate), lockDB, fn)
+	return r.withServicesUpdateLockedOperation(withDiscord, boolShareUpdateMode(autoShareUpdate), lockDB, "writer", fn)
+}
+
+func (r *runtime) withMessagesSyncServices(fn func() error) error {
+	return r.withServicesUpdateLockedOperation(true, shareUpdateConfigured, true, "messages-sync", fn)
 }
 
-func (r *runtime) withServicesUpdateLocked(withDiscord bool, updateMode shareUpdateMode, lockDB bool, fn func() error) error {
+func (r *runtime) withServicesUpdateLockedOperation(withDiscord bool, updateMode shareUpdateMode, lockDB bool, operation string, fn func() error) error {
 	cfg, err := config.Load(r.configPath)
 	if err != nil {
 		return configErr(err)
@@ -558,7 +569,13 @@ func (r *runtime) withServicesUpdateLocked(withDiscord bool, updateMode shareUpd
 	}
 	r.cfg = cfg
 	if lockDB {
-		return r.withSyncLock(func() error {
+		lockFn := r.withSyncLockOperation
+		if operation == "messages-sync" {
+			lockFn = func(_ string, fn func() error) error {
+				return r.withMessagesSyncLock(fn)
+			}
+		}
+		return lockFn(operation, func() error {
 			return r.openServices(dbPath, withDiscord, updateMode, fn)
 		})
 	}