feat(missions): per-mission taskPrefix override for triaged task ids

packages/core/src/__tests__/mission-store.test.ts

@@ -192,6 +192,24 @@ describe("MissionStore", () => {
       expect(store.getMission(mission.id)?.branchStrategy).toBeUndefined();
     });
 
+    it("round-trips mission taskPrefix on create", () => {
+      const mission = store.createMission({ title: "Prefixed", taskPrefix: "ERR" });
+      expect(store.getMission(mission.id)?.taskPrefix).toBe("ERR");
+    });
+
+    it("updates mission taskPrefix", () => {
+      const mission = store.createMission({ title: "Original" });
+      const updated = store.updateMission(mission.id, { taskPrefix: "BUG" });
+      expect(updated.taskPrefix).toBe("BUG");
+      expect(store.getMission(mission.id)?.taskPrefix).toBe("BUG");
+    });
+
+    it("reads undefined taskPrefix for legacy rows", () => {
+      const mission = store.createMission({ title: "Legacy row" });
+      db.prepare("UPDATE missions SET taskPrefix = NULL WHERE id = ?").run(mission.id);
+      expect(store.getMission(mission.id)?.taskPrefix).toBeUndefined();
+    });
+
     // FNXC:CoreTests 2026-06-25-21:50: real-sleep removed (FN-5048); advance the
     // fake clock between create and update so updatedAt > createdAt deterministically.
     it("updates a mission", () => {
@@ -2351,6 +2369,20 @@ describe("MissionStore", () => {
       expect(task!.missionId).toBe(mission.id);
     });
 
+    it("mints the triaged task id with the mission's taskPrefix", async () => {
+      const { TaskStore } = await import("../store.js");
+      const ts = new TaskStore(tmpDir, join(tmpDir, ".fusion-global-settings"), { inMemoryDb: true });
+      const msWithTs = ts.getMissionStore();
+
+      const mission = msWithTs.createMission({ title: "Mission", taskPrefix: "ERR" });
+      const milestone = msWithTs.addMilestone(mission.id, { title: "Milestone" });
+      const slice = msWithTs.addSlice(milestone.id, { title: "Slice" });
+      const feature = msWithTs.addFeature(slice.id, { title: "Feature" });
+
+      const triaged = await msWithTs.triageFeature(feature.id);
+      expect(triaged.taskId).toMatch(/^ERR-\d+$/);
+    });
+
     /*
     FNXC:MissionWorkflows 2026-06-25-00:00:
     MissionStore tests pin the storage invariant: workflowId is applied only to newly created mission-triage tasks, while default inheritance and duplicate-task reuse keep their existing workflow behavior.

packages/core/src/db.ts

@@ -183,7 +183,7 @@ export function isFts5CorruptionError(error: unknown): boolean {
 
 // ── Schema Definition ────────────────────────────────────────────────
 
-const SCHEMA_VERSION = 139;
+const SCHEMA_VERSION = 140;
 
 const TASKS_FTS_AUTOMERGE = 8;
 const TASKS_FTS_CRISISMERGE = 16;
@@ -956,6 +956,7 @@ CREATE TABLE IF NOT EXISTS missions (
   interviewState TEXT NOT NULL,
   baseBranch TEXT,
   branchStrategy TEXT,
+  taskPrefix TEXT,
   autoAdvance INTEGER DEFAULT 0,
   autoMerge INTEGER,
   createdAt TEXT NOT NULL,
@@ -5610,6 +5611,14 @@ export class Database {
       });
     }
 
+    if (version < 140) {
+      // Per-mission ticket id prefix (e.g. "ERR") for triaged tasks; NULL means
+      // inherit the project-wide taskPrefix setting. Additive-only, no backfill.
+      this.applyMigration(140, () => {
+        this.addColumnIfMissing("missions", "taskPrefix", "TEXT");
+      });
+    }
+
   }
 
   /**

packages/core/src/mission-store.ts

@@ -233,6 +233,7 @@ interface MissionRow {
   interviewState: string;
   baseBranch: string | null;
   branchStrategy: string | null;
+  taskPrefix: string | null;
   autoMerge: number | null;
   autoAdvance: number;
   autopilotEnabled: number;
@@ -435,6 +436,7 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
       interviewState: row.interviewState as InterviewState,
       baseBranch: row.baseBranch || undefined,
       branchStrategy,
+      taskPrefix: row.taskPrefix || undefined,
       autoMerge: row.autoMerge === null ? undefined : Boolean(row.autoMerge),
       autoAdvance: Boolean(row.autoAdvance),
       autopilotEnabled: Boolean(row.autopilotEnabled),
@@ -661,6 +663,7 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
       interviewState: "not_started",
       baseBranch: input.baseBranch,
       branchStrategy: input.branchStrategy,
+      taskPrefix: input.taskPrefix,
       autoMerge: input.autoMerge,
       autoAdvance: false,
       autopilotEnabled: false,
@@ -670,8 +673,8 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
     };
 
     this.db.prepare(`
-      INSERT INTO missions (id, title, description, status, interviewState, baseBranch, branchStrategy, autoMerge, autoAdvance, autopilotEnabled, autopilotState, createdAt, updatedAt)
-      VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+      INSERT INTO missions (id, title, description, status, interviewState, baseBranch, branchStrategy, taskPrefix, autoMerge, autoAdvance, autopilotEnabled, autopilotState, createdAt, updatedAt)
+      VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
     `).run(
       mission.id,
       mission.title,
@@ -680,6 +683,7 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
       mission.interviewState,
       mission.baseBranch ?? null,
       mission.branchStrategy ? JSON.stringify(mission.branchStrategy) : null,
+      mission.taskPrefix ?? null,
       mission.autoMerge === undefined ? null : (mission.autoMerge ? 1 : 0),
       mission.autoAdvance ? 1 : 0,
       mission.autopilotEnabled ? 1 : 0,
@@ -1276,6 +1280,7 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
         interviewState = ?,
         baseBranch = ?,
         branchStrategy = ?,
+        taskPrefix = ?,
         autoMerge = ?,
         autoAdvance = ?,
         autopilotEnabled = ?,
@@ -1290,6 +1295,7 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
       updated.interviewState,
       updated.baseBranch ?? null,
       updated.branchStrategy ? JSON.stringify(updated.branchStrategy) : null,
+      updated.taskPrefix ?? null,
       updated.autoMerge === undefined ? null : (updated.autoMerge ? 1 : 0),
       updated.autoAdvance ? 1 : 0,
       updated.autopilotEnabled ? 1 : 0,
@@ -3978,6 +3984,7 @@ export class MissionStore extends EventEmitter<MissionStoreEvents> {
           description,
           branch: branchAssignment.workingBranch,
           baseBranch: resolvedBaseBranch,
+          taskPrefix: mission?.taskPrefix,
           ...(missionId
             ? {
                 branchContext: {

packages/core/src/mission-types.ts

@@ -139,6 +139,8 @@ export interface Mission {
   baseBranch?: string;
   /** Mission triage branch strategy: auto-per-task => assignmentMode "per-task-derived"; existing/custom-new => shared branchName; project-default/absent => shared default behavior. */
   branchStrategy?: MissionBranchStrategy;
+  /** Per-mission ticket id prefix for triaged tasks (e.g. "ERR"). Absent => inherit the project-wide taskPrefix setting. */
+  taskPrefix?: string;
   /** State of the AI specification interview process */
   interviewState: InterviewState;
   /**
@@ -392,6 +394,8 @@ export interface MissionCreateInput {
   baseBranch?: string;
   /** Optional branch strategy applied as the default for mission triage operations. */
   branchStrategy?: MissionBranchStrategy;
+  /** Optional per-mission ticket id prefix for triaged tasks (e.g. "ERR"); inherits the project setting when absent. */
+  taskPrefix?: string;
   /** Optional mission-level auto-merge override for linked task branches. */
   autoMerge?: boolean;
 }

packages/core/src/store.ts

@@ -4451,7 +4451,9 @@ ${TASK_UPSERT_SQL_ASSIGNMENTS}
     },
   ): Promise<Task> {
     const settings = await this.getSettingsFast();
-    const prefix = (settings.taskPrefix || "FN").trim().toUpperCase();
+    // A per-mission taskPrefix (threaded via TaskCreateInput at triage time)
+    // overrides the project-wide setting for this task's id reservation.
+    const prefix = (input.taskPrefix?.trim() || settings.taskPrefix || "FN").trim().toUpperCase();
     const allocator = this.getDistributedTaskIdAllocator();
     const nodeId = await this.resolveLocalNodeIdForTaskAllocation();
     const reservation = await allocator.reserveDistributedTaskId({

packages/core/src/types.ts

@@ -2703,6 +2703,9 @@ export interface TaskCreateInput {
   branch?: string;
   /** Optional planning/mission branch-group metadata carried across related tasks. */
   branchContext?: TaskBranchContext;
+  /** Transient minting hint: overrides the project taskPrefix for this task's id
+   *  reservation (used by mission triage to honor a per-mission prefix). Not persisted. */
+  taskPrefix?: string;
   /** Optional per-task auto-merge override. Undefined means no task-level override. */
   autoMerge?: boolean;
   /** Durable source provenance for the originating external issue. */

packages/dashboard/app/api/legacy.ts

@@ -7930,6 +7930,8 @@ export interface Mission {
     mode: "project-default" | "existing" | "custom-new" | "auto-per-task";
     branchName?: string;
   };
+  /** Per-mission ticket id prefix (e.g. "ERR"); undefined inherits the project prefix. */
+  taskPrefix?: string;
   status: MissionStatus;
   interviewState: "not_started" | "in_progress" | "completed" | "needs_update";
   autoAdvance?: boolean;
@@ -8021,7 +8023,7 @@ export function fetchMissions(projectId?: string): Promise<MissionWithSummary[]>
 }
 
 /** Create a new mission */
-export function createMission(input: { title: string; description?: string; autoAdvance?: boolean; autopilotEnabled?: boolean; baseBranch?: string; branchStrategy?: Mission["branchStrategy"] }, projectId?: string): Promise<Mission> {
+export function createMission(input: { title: string; description?: string; autoAdvance?: boolean; autopilotEnabled?: boolean; baseBranch?: string; branchStrategy?: Mission["branchStrategy"]; taskPrefix?: string }, projectId?: string): Promise<Mission> {
   return api<Mission>(withProjectId("/missions", projectId), {
     method: "POST",
     body: JSON.stringify(input),

packages/dashboard/app/components/MissionManager.tsx

@@ -294,6 +294,7 @@ interface MissionFormData {
   autopilotEnabled: boolean;
   baseBranch: string;
   branchStrategy: MissionBranchStrategy;
+  taskPrefix: string;
 }
 
 interface MilestoneFormData {
@@ -326,6 +327,7 @@ const EMPTY_MISSION_FORM: MissionFormData = {
   branchStrategy: {
     mode: "project-default",
   },
+  taskPrefix: "",
 };
 
 const EMPTY_MILESTONE_FORM: MilestoneFormData = {
@@ -1611,6 +1613,7 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
       autopilotEnabled: mission.autopilotEnabled ?? false,
       baseBranch: mission.baseBranch ?? "",
       branchStrategy: normalizeMissionBranchStrategy(mission.branchStrategy),
+      taskPrefix: mission.taskPrefix ?? "",
     });
   }, []);
 
@@ -1648,6 +1651,7 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
           autopilotEnabled: missionForm.autopilotEnabled,
           baseBranch: missionForm.baseBranch.trim() || undefined,
           branchStrategy,
+          taskPrefix: missionForm.taskPrefix.trim() || undefined,
         }, projectId);
         addToast(t("missions.created", "Mission created"), "success");
       } else if (editingMissionId) {
@@ -1660,6 +1664,7 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
           autopilotEnabled: missionForm.autopilotEnabled,
           baseBranch: missionForm.baseBranch.trim() || "",
           branchStrategy,
+          taskPrefix: missionForm.taskPrefix.trim() || undefined,
         };
         if (missionForm.autopilotEnabled) {
           updates.autoAdvance = true;
@@ -2810,6 +2815,16 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
                       aria-label={t("missions.missionTargetBranchAriaLabel", "Mission target branch")}
                     />
                   </label>
+                  <label>
+                    {t("missions.taskPrefix", "Task prefix")}
+                    <input
+                      type="text"
+                      placeholder={t("missions.taskPrefixPlaceholder", "e.g. ERR (defaults to project prefix)")}
+                      value={missionForm.taskPrefix}
+                      onChange={(e) => setMissionForm({ ...missionForm, taskPrefix: e.target.value.toUpperCase() })}
+                      aria-label={t("missions.taskPrefixAriaLabel", "Mission task prefix")}
+                    />
+                  </label>
                   <label>
                     {t("missions.branchStrategy", "Branch strategy")}
                     <select
@@ -4535,6 +4550,16 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
                       aria-label={t("missions.missionTargetBranchAriaLabel", "Mission target branch")}
                     />
                   </label>
+                  <label>
+                    {t("missions.taskPrefix", "Task prefix")}
+                    <input
+                      type="text"
+                      placeholder={t("missions.taskPrefixPlaceholder", "e.g. ERR (defaults to project prefix)")}
+                      value={missionForm.taskPrefix}
+                      onChange={(e) => setMissionForm({ ...missionForm, taskPrefix: e.target.value.toUpperCase() })}
+                      aria-label={t("missions.taskPrefixAriaLabel", "Mission task prefix")}
+                    />
+                  </label>
                   <label>
                     {t("missions.branchStrategy", "Branch strategy")}
                     <select
@@ -4629,6 +4654,16 @@ export function MissionManager({ isOpen, isInline = false, onClose, addToast, pr
                       aria-label={t("missions.missionTargetBranchAriaLabel", "Mission target branch")}
                     />
                   </label>
+                  <label>
+                    {t("missions.taskPrefix", "Task prefix")}
+                    <input
+                      type="text"
+                      placeholder={t("missions.taskPrefixPlaceholder", "e.g. ERR (defaults to project prefix)")}
+                      value={missionForm.taskPrefix}
+                      onChange={(e) => setMissionForm({ ...missionForm, taskPrefix: e.target.value.toUpperCase() })}
+                      aria-label={t("missions.taskPrefixAriaLabel", "Mission task prefix")}
+                    />
+                  </label>
                   <label>
                     {t("missions.branchStrategy", "Branch strategy")}
                     <select

packages/dashboard/app/components/mission-types.ts

@@ -56,6 +56,7 @@ export interface Mission {
     mode: "project-default" | "existing" | "custom-new" | "auto-per-task";
     branchName?: string;
   };
+  taskPrefix?: string;
   status: MissionStatus;
   interviewState: "not_started" | "in_progress" | "completed" | "needs_update";
   autoAdvance?: boolean;

packages/dashboard/src/mission-routes.ts

@@ -180,6 +180,19 @@ function validateMissionBranchStrategy(value: unknown): MissionBranchStrategy |
   };
 }
 
+function validateTaskPrefix(value: unknown): string | undefined {
+  if (value === undefined || value === null) return undefined;
+  if (typeof value !== "string") {
+    throw new Error("taskPrefix must be a string");
+  }
+  const trimmed = value.trim().toUpperCase();
+  if (!trimmed) return undefined; // empty => inherit the project prefix
+  if (!/^[A-Z][A-Z0-9]*$/.test(trimmed)) {
+    throw new Error("taskPrefix must start with a letter and contain only letters and digits");
+  }
+  return trimmed;
+}
+
 function validateOrderedIds(body: unknown): string[] {
   if (!body || typeof body !== "object") {
     throw new Error("Request body must contain orderedIds array");
@@ -444,7 +457,7 @@ export function createMissionRouter(
   router.post(
     "/",
     catchTypedHandler(async (req, res) => {
-      const { title, description, autoAdvance, baseBranch, branchStrategy, goalIds } = req.body;
+      const { title, description, autoAdvance, baseBranch, branchStrategy, taskPrefix, goalIds } = req.body;
 
       const validatedTitle = validateTitle(title);
       const validatedDescription = validateDescription(description);
@@ -455,6 +468,7 @@ export function createMissionRouter(
         description: validatedDescription,
         baseBranch: validateDescription(baseBranch),
         branchStrategy: validateMissionBranchStrategy(branchStrategy),
+        taskPrefix: validateTaskPrefix(taskPrefix),
       };
 
       const mission = missionStore.createMission(input);
@@ -1120,7 +1134,7 @@ export function createMissionRouter(
     "/:missionId",
     catchTypedHandler(async (req, res) => {
       const { missionId } = req.params;
-      const { title, description, status, autoAdvance, autopilotEnabled, baseBranch, branchStrategy, goalIds } = req.body;
+      const { title, description, status, autoAdvance, autopilotEnabled, baseBranch, branchStrategy, taskPrefix, goalIds } = req.body;
 
       if (!validateMissionId(missionId)) {
         throw badRequest("Invalid mission ID format");
@@ -1151,6 +1165,9 @@ export function createMissionRouter(
       if (branchStrategy !== undefined) {
         updates.branchStrategy = validateMissionBranchStrategy(branchStrategy);
       }
+      if (taskPrefix !== undefined) {
+        updates.taskPrefix = validateTaskPrefix(taskPrefix);
+      }
 
       if (Object.keys(updates).length === 0 && validatedGoalIds === undefined) {
         throw badRequest("No valid fields to update");

packages/engine/src/__tests__/worktree-hooks.test.ts

@@ -84,6 +84,15 @@ describe("worktree-hooks", () => {
     expect(hook).toContain("s/^KB-//i");
   });
 
+  it("derives the strip prefix from the task id, ignoring a mismatched options.taskPrefix", () => {
+    // A per-mission ticket (ERR-5) whose project-wide options.taskPrefix is
+    // still "FN" must strip its own ERR- prefix, not "FN-".
+    const hook = buildCommitMsgTrailerHook("ERR-5", { taskPrefix: "FN" });
+    expect(hook).toContain('PREFIX="ERR"');
+    expect(hook).toContain("s/^ERR-//i");
+    expect(hook).not.toContain('PREFIX="FN"');
+  });
+
   it("installs metadata and pre-commit + commit-msg hooks in linked worktree", async () => {
     const root = mkdtempSync(join(tmpdir(), "wt-hook-root-"));
     execFileSync("git", ["init"], { cwd: root });

packages/engine/src/worktree-hooks.ts

@@ -207,7 +207,16 @@ export function buildCommitMsgTrailerHook(
     commitAuthorEmail?: string;
   } = {}
 ): string {
-  const taskPrefix = (options.taskPrefix ?? "FN").trim() || "FN";
+  // Derive the strip prefix from the task id itself so per-mission prefixes
+  // (e.g. ERR-5 while the project taskPrefix is still "FN") strip correctly.
+  // The fusion-task-id file holds the real id, so PREFIX must match it, not the
+  // project-wide options.taskPrefix. Falls back to options.taskPrefix / "FN"
+  // only when taskId isn't a well-formed "<PREFIX>-<n>".
+  const trimmedTaskId = taskId.trim();
+  const derivedPrefix = /^[A-Za-z][A-Za-z0-9]*-\d+$/.test(trimmedTaskId)
+    ? trimmedTaskId.replace(/-\d+$/, "").toUpperCase()
+    : "";
+  const taskPrefix = (derivedPrefix || options.taskPrefix || "FN").trim() || "FN";
   const trailerName = (options.trailerName ?? "Fusion-Task-Id").trim() || "Fusion-Task-Id";
   const commitAuthorName = (options.commitAuthorName ?? DEFAULT_COMMIT_AUTHOR_NAME).trim() || DEFAULT_COMMIT_AUTHOR_NAME;
   const commitAuthorEmail = (options.commitAuthorEmail ?? DEFAULT_COMMIT_AUTHOR_EMAIL).trim() || DEFAULT_COMMIT_AUTHOR_EMAIL;