fix(FN-5089): add trailer settings typing defaults

Fusion-Task-Id: FN-5089
Fusion-Task-Lineage: ad7ea32a-c024-45bb-b68e-b65665b9b7c6

packages/core/src/settings-schema.ts

@@ -215,6 +215,7 @@ export const DEFAULT_PROJECT_SETTINGS = {
   },
   worktreesDir: undefined,
   taskPrefix: "FN",
+  taskAttributionTrailerNames: ["Fusion-Task-Id"],
   commitMsgHookEnabled: true,
   includeTaskIdInCommit: true,
   commitAuthorEnabled: true,

packages/core/src/types.ts

@@ -2724,6 +2724,10 @@ export interface ProjectSettings {
    *  Defaults to `"KB"`. Only affects new tasks — existing tasks retain
    *  their original IDs. */
   taskPrefix?: string;
+  /** Preferred commit trailer keys for task attribution in priority order.
+   *  The first value is used by commit-msg hook installation when enabled.
+   *  Defaults to `["Fusion-Task-Id"]`. */
+  taskAttributionTrailerNames?: string[];
   /** When true, Fusion installs a commit-msg hook in managed task worktrees
    *  that appends the configured task attribution trailer (e.g. `Fusion-Task-Id: FN-123`).
    *  Set to false for projects with custom hook infrastructure. Default: true. */

packages/engine/src/worktree-backend.ts

@@ -172,7 +172,7 @@ export class NativeWorktreeBackend implements WorktreeBackend {
   constructor(
     private readonly deps: {
       logger?: { log: (m: string) => void; warn: (m: string) => void };
-      settings?: Pick<Settings, "worktreesDir" | "commitMsgHookEnabled" | "taskPrefix" | "taskAttributionTrailerNames">;
+      settings?: Partial<Pick<Settings, "worktreesDir" | "commitMsgHookEnabled" | "taskPrefix" | "taskAttributionTrailerNames">>;
       audit?: Pick<RunAuditor, "git">;
     } = {},
   ) {}
@@ -552,9 +552,6 @@ export class WorktrunkWorktreeBackend implements WorktreeBackend {
       await installTaskWorktreeIdentityGuard({
         worktreePath: resolvedPath,
         taskId: input.taskId,
-        commitMsgHookEnabled: this.deps.settings?.commitMsgHookEnabled,
-        taskPrefix: this.deps.settings?.taskPrefix,
-        taskAttributionTrailerName: this.deps.settings?.taskAttributionTrailerNames?.[0],
       });
     } catch (error) {
       await execAsync(`rm -rf ${quoteShellArg(resolvedPath)}`, {