diff --git a/src/worker.nim b/src/worker.nim
index 559de73..a1d932e 100644
--- a/src/worker.nim
+++ b/src/worker.nim
@@ -12,7 +12,7 @@
 import std/[os, strformat, json, times, terminal, strutils, sequtils]
 import cligen
 import tiny_sqlite
-import worker/[types, db, state, git, context, heartbeat]
+import worker/[types, db, state, git, context, heartbeat, utils]
 
 # -----------------------------------------------------------------------------
 # Orchestrator Commands
@@ -21,6 +21,7 @@ import worker/[types, db, state, git, context, heartbeat]
 proc spawn(taskId: string, description: string = "",
            fromBranch: string = "origin/integration") =
   ## Create a new worker workspace
+  discard validateTaskId(taskId)
   let db = openBusDb()
   defer: db.close()
 
@@ -120,6 +121,7 @@ proc status(state: string = "", stale: bool = false,
 
 proc approve(taskId: string, by: string = "", comment: string = "") =
   ## Approve completed work (IN_REVIEW → APPROVED)
+  discard validateTaskId(taskId)
   let db = openBusDb()
   defer: db.close()
 
@@ -128,6 +130,7 @@ proc approve(taskId: string, by: string = "", comment: string = "") =
 
 proc requestChanges(taskId: string, comment: string = "") =
   ## Request revisions (IN_REVIEW → WORKING)
+  discard validateTaskId(taskId)
   let db = openBusDb()
   defer: db.close()
 
@@ -138,6 +141,7 @@ proc requestChanges(taskId: string, comment: string = "") =
 
 proc merge(taskId: string, deleteBranch: bool = false) =
   ## Merge approved work (APPROVED → COMPLETED)
+  discard validateTaskId(taskId)
   let db = openBusDb()
   defer: db.close()
 
@@ -168,6 +172,7 @@ proc merge(taskId: string, deleteBranch: bool = false) =
 
 proc cancel(taskId: string, reason: string = "", cleanup: bool = false) =
   ## Abort a worker (* → FAILED)
+  discard validateTaskId(taskId)
   let db = openBusDb()
   defer: db.close()
 
@@ -184,7 +189,7 @@ proc cancel(taskId: string, reason: string = "", cleanup: bool = false) =
 
 proc start(task: string = "") =
   ## Signal ASSIGNED → WORKING (run from worktree)
-  let taskId = if task != "": task else: getTaskId()
+  let taskId = if task != "": validateTaskId(task) else: getTaskId()
 
   let db = openBusDb()
   defer: db.close()
@@ -284,6 +289,7 @@ proc sendHeartbeat(status: string = "working", progress: float = 0.0) =
 
 proc show(taskId: string) =
   ## Show detailed view of a worker
+  discard validateTaskId(taskId)
   let db = openBusDb()
   defer: db.close()
 
diff --git a/src/worker/git.nim b/src/worker/git.nim
index a03e225..e9cf0f1 100644
--- a/src/worker/git.nim
+++ b/src/worker/git.nim
@@ -5,6 +5,7 @@
 
 import std/[os, osproc, strutils, strformat, streams]
 import ./types
+import ./utils
 
 proc runGit*(args: varargs[string], workDir: string = ""): tuple[output: string, exitCode: int] =
   ## Run a git command and return output + exit code
@@ -33,8 +34,8 @@ proc runGitCheck*(args: varargs[string], workDir: string = ""): string =
 
 proc createWorktree*(taskId: string, fromBranch: string = "origin/integration"): tuple[branch, worktree: string] =
   ## Create a worktree for a task
-  let branch = &"feat/{taskId}"
-  let worktree = &"{WorktreesDir}/{taskId}"
+  let branch = branchName(taskId)
+  let worktree = worktreePath(taskId)
 
   # Fetch latest
   discard runGit("fetch", "origin")
@@ -50,13 +51,13 @@ proc createWorktree*(taskId: string, fromBranch: string = "origin/integration"):
 
 proc removeWorktree*(taskId: string) =
   ## Remove a worktree
-  let worktree = &"{WorktreesDir}/{taskId}"
+  let worktree = worktreePath(taskId)
   if dirExists(worktree):
     discard runGit("worktree", "remove", "--force", worktree)
 
 proc removeBranch*(taskId: string, remote: bool = true) =
   ## Remove feature branch
-  let branch = &"feat/{taskId}"
+  let branch = branchName(taskId)
   discard runGit("branch", "-D", branch)
   if remote:
     discard runGit("push", "origin", "--delete", branch)
@@ -86,7 +87,7 @@ proc pushBranch*(worktree: string, branch: string) =
 
 proc mergeToIntegration*(taskId: string, maxRetries: int = 3): bool =
   ## Merge feature branch to integration with retry loop
-  let branch = &"feat/{taskId}"
+  let branch = branchName(taskId)
 
   for attempt in 1..maxRetries:
     # Fetch latest
diff --git a/src/worker/state.nim b/src/worker/state.nim
index 02640a9..43fdbe5 100644
--- a/src/worker/state.nim
+++ b/src/worker/state.nim
@@ -11,6 +11,7 @@ import std/[tables, strformat, json, options, times]
 import tiny_sqlite
 import ./types
 import ./db
+import ./utils
 
 const ValidTransitions* = {
   wsAssigned: @[wsWorking, wsFailed],
@@ -138,8 +139,8 @@ proc getWorker*(db: DbConn, taskId: string): Option[WorkerInfo] =
     state: parseState(row.get[1].fromDbValue(string)),
     branch: row.get[2].fromDbValue(string),
     worktree: row.get[3].fromDbValue(string),
-    createdAt: fromUnix(row.get[5].fromDbValue(int64) div 1000),
-    stateChangedAt: fromUnix(row.get[6].fromDbValue(int64) div 1000),
+    createdAt: msToTime(row.get[5].fromDbValue(int64)),
+    stateChangedAt: msToTime(row.get[6].fromDbValue(int64)),
   )
 
   if row.get[4].kind != sqliteNull:
@@ -148,7 +149,7 @@ proc getWorker*(db: DbConn, taskId: string): Option[WorkerInfo] =
   # Get heartbeat
   let hb = db.getHeartbeat(taskId)
   if hb.isSome:
-    info.lastHeartbeat = fromUnix(hb.get.tsMs div 1000)
+    info.lastHeartbeat = msToTime(hb.get.tsMs)
 
   return some(info)
 
@@ -167,15 +168,15 @@ proc getAllWorkers*(db: DbConn): seq[WorkerInfo] =
       state: parseState(row[1].fromDbValue(string)),
       branch: row[2].fromDbValue(string),
       worktree: row[3].fromDbValue(string),
-      createdAt: fromUnix(row[5].fromDbValue(int64) div 1000),
-      stateChangedAt: fromUnix(row[6].fromDbValue(int64) div 1000),
+      createdAt: msToTime(row[5].fromDbValue(int64)),
+      stateChangedAt: msToTime(row[6].fromDbValue(int64)),
     )
 
     if row[4].kind != sqliteNull:
       info.description = row[4].fromDbValue(string)
 
     if row[7].kind != sqliteNull:
-      info.lastHeartbeat = fromUnix(row[7].fromDbValue(int64) div 1000)
+      info.lastHeartbeat = msToTime(row[7].fromDbValue(int64))
 
     result.add(info)
 
@@ -207,8 +208,8 @@ proc createWorker*(db: DbConn, taskId, branch, worktree: string,
     branch: branch,
     worktree: worktree,
     description: description,
-    createdAt: fromUnix(tsMs div 1000),
-    stateChangedAt: fromUnix(tsMs div 1000),
+    createdAt: msToTime(tsMs),
+    stateChangedAt: msToTime(tsMs),
   )
 
 proc isStale*(info: WorkerInfo): bool =
diff --git a/src/worker/utils.nim b/src/worker/utils.nim
new file mode 100644
index 0000000..9db6ad8
--- /dev/null
+++ b/src/worker/utils.nim
@@ -0,0 +1,62 @@
+## Common utilities for worker coordination
+##
+## Consolidates repeated patterns across modules.
+
+import std/[strformat, times, options]
+import tiny_sqlite
+import ./types
+
+# Path helpers
+proc branchName*(taskId: string): string =
+  ## Get the feature branch name for a task
+  &"feat/{taskId}"
+
+proc worktreePath*(taskId: string): string =
+  ## Get the worktree path for a task
+  &"{WorktreesDir}/{taskId}"
+
+# Time conversion
+proc msToTime*(ms: int64): Time =
+  ## Convert epoch milliseconds to Time
+  fromUnix(ms div 1000)
+
+# Input validation
+const AllowedTaskIdChars = {'a'..'z', 'A'..'Z', '0'..'9', '_', '-'}
+
+proc validateTaskId*(taskId: string): string =
+  ## Validate task ID to prevent path traversal and injection.
+  ## Returns the taskId if valid, raises ValueError otherwise.
+  if taskId.len == 0:
+    raise newException(ValueError, "Task ID cannot be empty")
+  if taskId.len > 64:
+    raise newException(ValueError, "Task ID too long (max 64 chars)")
+  for c in taskId:
+    if c notin AllowedTaskIdChars:
+      raise newException(ValueError, "Task ID contains invalid character: " & $c)
+  return taskId
+
+# SQLite helpers
+proc optString*(val: DbValue): Option[string] =
+  ## Convert nullable DbValue to Option[string]
+  if val.kind == sqliteNull:
+    none(string)
+  else:
+    some(val.fromDbValue(string))
+
+proc optInt64*(val: DbValue): Option[int64] =
+  ## Convert nullable DbValue to Option[int64]
+  if val.kind == sqliteNull:
+    none(int64)
+  else:
+    some(val.fromDbValue(int64))
+
+# Transaction helper
+template withTransaction*(db: DbConn, body: untyped) =
+  ## Execute body within a transaction with automatic rollback on error.
+  db.exec("BEGIN IMMEDIATE")
+  try:
+    body
+    db.exec("COMMIT")
+  except CatchableError:
+    db.exec("ROLLBACK")
+    raise