diff --git a/packages/core/src/__tests__/migration-workflow-columns.test.ts b/packages/core/src/__tests__/migration-workflow-columns.test.ts
index 6cedf60893..c92259fcf7 100644
--- a/packages/core/src/__tests__/migration-workflow-columns.test.ts
+++ b/packages/core/src/__tests__/migration-workflow-columns.test.ts
@@ -219,24 +219,18 @@ describe("U12 rollback safety — flag OFF after flag ON keeps legacy behavior",
     await store.selectTaskWorkflowAndReconcile(task.id, wf.id);
     expect((await store.getTask(task.id)).column).toBe("intake");
 
-    // Toggle the flag OFF — the card stays in the custom "intake" column.
+    // Toggle the flag OFF — #1409: the ON→OFF evacuation re-homes the card from
+    // the custom "intake" column to the nearest legacy column (the default
+    // workflow's entry column, triage) so it is not stranded on the legacy path.
     await store.updateGlobalSettings({ experimentalFeatures: { workflowColumns: false } });
-    expect((await store.getTask(task.id)).column).toBe("intake");
+    expect((await store.getTask(task.id)).column).toBe("triage");
 
-    // listTasks must not throw with a task sitting in an unknown column.
+    // listTasks stays healthy.
     await expect(store.listTasks()).resolves.toBeDefined();
 
-    // A move attempt degrades to the legacy "Invalid transition" error rather
-    // than a TypeError on the undefined VALID_TRANSITIONS lookup.
-    let caught: unknown;
-    try {
-      await store.moveTask(task.id, "in-progress", { moveSource: "user" });
-    } catch (e) {
-      caught = e;
-    }
-    expect(caught).toBeInstanceOf(Error);
-    expect((caught as Error).message).toMatch(/Invalid transition/);
-    expect((caught as Error)).not.toBeInstanceOf(TypeError);
+    // The evacuated card now moves legacy-style: triage → todo works.
+    await store.moveTask(task.id, "todo", { moveSource: "user" });
+    expect((await store.getTask(task.id)).column).toBe("todo");
   });
 });
 
diff --git a/packages/core/src/__tests__/transition-pending-recovery.test.ts b/packages/core/src/__tests__/transition-pending-recovery.test.ts
new file mode 100644
index 0000000000..064393f800
--- /dev/null
+++ b/packages/core/src/__tests__/transition-pending-recovery.test.ts
@@ -0,0 +1,195 @@
+// @vitest-environment node
+//
+// #1401 + #1409: store-level recovery / evacuation passes for the workflow
+// columns feature.
+//
+//   #1401 — transitionPending recovery sweep:
+//     * a crash-simulated stale marker is recovered (cleared) by the sweep,
+//     * the phantom capacity slot the marker reserved is released so a fresh
+//       card can re-enter a full (capacity=1) column afterwards,
+//     * the sweep is idempotent (a second run finds nothing).
+//
+//   #1409 — flag ON→OFF evacuation:
+//     * toggling workflowColumns OFF with a card in a custom column re-homes it
+//       to a legacy column, the board stays listable, and legacy moves work.
+//     * a flag-OFF store init evacuates a card left in a custom column.
+
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { createTaskStoreTestHarness } from "./store-test-helpers.js";
+import type { WorkflowIr } from "../workflow-ir-types.js";
+import { makeTransitionPending, serializeTransitionPending } from "../transition-types.js";
+
+/** A custom workflow whose middle column carries a WIP capacity limit of 1. */
+function cappedIr(): WorkflowIr {
+  return {
+    version: "v2",
+    name: "capped",
+    columns: [
+      { id: "intake", name: "intake", traits: [{ trait: "intake" }] },
+      {
+        id: "build",
+        name: "build",
+        traits: [{ trait: "wip", config: { limit: 1, countPending: true } }],
+      },
+      { id: "ship", name: "ship", traits: [] },
+    ],
+    nodes: [
+      { id: "start", kind: "start", column: "intake" },
+      { id: "work", kind: "prompt", column: "build", config: { prompt: "do" } },
+      { id: "end", kind: "end", column: "ship" },
+    ],
+    edges: [
+      { from: "start", to: "work", condition: "success" },
+      { from: "work", to: "end", condition: "success" },
+    ],
+  };
+}
+
+function simpleCustomIr(): WorkflowIr {
+  return {
+    version: "v2",
+    name: "simple-custom",
+    columns: [
+      { id: "intake", name: "intake", traits: [{ trait: "intake" }] },
+      { id: "build", name: "build", traits: [] },
+      { id: "ship", name: "ship", traits: [] },
+    ],
+    nodes: [
+      { id: "start", kind: "start", column: "intake" },
+      { id: "work", kind: "prompt", column: "build", config: { prompt: "do" } },
+      { id: "end", kind: "end", column: "ship" },
+    ],
+    edges: [
+      { from: "start", to: "work", condition: "success" },
+      { from: "work", to: "end", condition: "success" },
+    ],
+  };
+}
+
+describe("#1401 transitionPending recovery sweep", () => {
+  const harness = createTaskStoreTestHarness();
+  let store: ReturnType<typeof harness.store>;
+
+  beforeEach(async () => {
+    await harness.beforeEach();
+    store = harness.store();
+    await store.updateGlobalSettings({ experimentalFeatures: { workflowColumns: true } });
+  });
+  afterEach(async () => {
+    await harness.afterEach();
+  });
+
+  function rawDb(): {
+    prepare: (s: string) => { run: (...a: unknown[]) => unknown; get: (...a: unknown[]) => unknown };
+  } {
+    return (store as unknown as { db: ReturnType<typeof rawDb> }).db;
+  }
+
+  function readMarkerColumn(taskId: string): string | null {
+    const row = rawDb()
+      .prepare(`SELECT transitionPending FROM tasks WHERE id = ?`)
+      .get(taskId) as { transitionPending: string | null } | undefined;
+    return row?.transitionPending ?? null;
+  }
+
+  it("recovers a crash-simulated stale marker and is idempotent", async () => {
+    const t = await store.createTask({ description: "stale-marker" });
+    // Simulate a crash that left a transitionPending marker set forever.
+    const marker = serializeTransitionPending(
+      makeTransitionPending("build", ["default-workflow:postCommit"], Date.now() - 60_000),
+    );
+    rawDb().prepare(`UPDATE tasks SET transitionPending = ? WHERE id = ?`).run(marker, t.id);
+    expect(readMarkerColumn(t.id)).not.toBeNull();
+
+    const first = await store.recoverStaleTransitionPending();
+    expect(first.scanned).toBeGreaterThanOrEqual(1);
+    expect(first.recovered).toBe(1);
+    // Marker cleared → capacity slot released.
+    expect(readMarkerColumn(t.id)).toBeNull();
+
+    // Idempotent: nothing left to recover.
+    const second = await store.recoverStaleTransitionPending();
+    expect(second.recovered).toBe(0);
+  });
+
+  it("releases the phantom capacity slot a stale marker reserved (count returns to normal)", async () => {
+    const wf = await store.createWorkflowDefinition({ name: "capped", ir: cappedIr() });
+
+    // A "ghost" task crashed mid-transition into the capacity-1 "build" column:
+    // its marker reserves the only slot even though it never committed there.
+    const ghost = await store.createTask({ description: "ghost" });
+    await store.selectTaskWorkflowAndReconcile(ghost.id, wf.id);
+    const ghostMarker = serializeTransitionPending(
+      makeTransitionPending("build", ["default-workflow:postCommit"], Date.now() - 60_000),
+    );
+    rawDb().prepare(`UPDATE tasks SET transitionPending = ? WHERE id = ?`).run(ghostMarker, ghost.id);
+
+    // A fresh card in the same workflow cannot enter "build": the phantom marker
+    // is counted as occupying the single capacity slot.
+    const fresh = await store.createTask({ description: "fresh" });
+    await store.selectTaskWorkflowAndReconcile(fresh.id, wf.id);
+    expect((await store.getTask(fresh.id)).column).toBe("intake");
+
+    let blocked: unknown;
+    try {
+      await store.moveTask(fresh.id, "build", { moveSource: "user" });
+    } catch (e) {
+      blocked = e;
+    }
+    expect(blocked).toBeInstanceOf(Error);
+    expect((await store.getTask(fresh.id)).column).toBe("intake");
+
+    // Recovery clears the stale marker, releasing the slot.
+    const result = await store.recoverStaleTransitionPending();
+    expect(result.recovered).toBeGreaterThanOrEqual(1);
+
+    // Now the fresh card can enter the capacity column.
+    await store.moveTask(fresh.id, "build", { moveSource: "user" });
+    expect((await store.getTask(fresh.id)).column).toBe("build");
+  });
+});
+
+describe("#1409 flag ON→OFF evacuation", () => {
+  const harness = createTaskStoreTestHarness();
+  let store: ReturnType<typeof harness.store>;
+
+  beforeEach(async () => {
+    await harness.beforeEach();
+    store = harness.store();
+  });
+  afterEach(async () => {
+    await harness.afterEach();
+  });
+
+  it("toggling OFF re-homes a card from a custom column to a legacy column; moves work", async () => {
+    await store.updateGlobalSettings({ experimentalFeatures: { workflowColumns: true } });
+    const wf = await store.createWorkflowDefinition({ name: "simple-custom", ir: simpleCustomIr() });
+    const task = await store.createTask({ description: "evac" });
+    await store.selectTaskWorkflowAndReconcile(task.id, wf.id);
+    expect((await store.getTask(task.id)).column).toBe("intake");
+
+    // Toggle OFF — evacuation re-homes the card to the nearest legacy column
+    // (the default workflow's entry column, triage).
+    await store.updateGlobalSettings({ experimentalFeatures: { workflowColumns: false } });
+    expect((await store.getTask(task.id)).column).toBe("triage");
+
+    // Board listable; legacy moves work from the evacuated column.
+    await expect(store.listTasks()).resolves.toBeDefined();
+    await store.moveTask(task.id, "todo", { moveSource: "user" });
+    await store.moveTask(task.id, "in-progress", { moveSource: "user" });
+    expect((await store.getTask(task.id)).column).toBe("in-progress");
+  });
+
+  it("evacuateCustomColumnsToLegacy is idempotent (a second run is a no-op)", async () => {
+    await store.updateGlobalSettings({ experimentalFeatures: { workflowColumns: true } });
+    const wf = await store.createWorkflowDefinition({ name: "simple-custom-2", ir: simpleCustomIr() });
+    const task = await store.createTask({ description: "evac2" });
+    await store.selectTaskWorkflowAndReconcile(task.id, wf.id);
+    await store.updateGlobalSettings({ experimentalFeatures: { workflowColumns: false } });
+
+    // First explicit run already evacuated (via the toggle); a fresh run is a no-op.
+    const again = await store.evacuateCustomColumnsToLegacy("flag-off-init");
+    expect(again.evacuated).toBe(0);
+    expect((await store.getTask(task.id)).column).toBe("triage");
+  });
+});
diff --git a/packages/core/src/store.ts b/packages/core/src/store.ts
index d519411fe6..da180873cc 100644
--- a/packages/core/src/store.ts
+++ b/packages/core/src/store.ts
@@ -5,7 +5,7 @@ import { join } from "node:path";
 import { existsSync, watch, type FSWatcher } from "node:fs";
 import type { Task, TaskDetail, TaskCreateInput, TaskAttachment, AgentLogEntry, BoardConfig, Column, ColumnId, CheckoutClaimPrecondition, MergeResult, Settings, GlobalSettings, ProjectSettings, ActivityLogEntry, ActivityEventType, TaskDocument, TaskDocumentRevision, TaskDocumentCreateInput, TaskDocumentWithTask, InboxTask, TaskLogEntry, RunMutationContext, RunAuditEvent, RunAuditEventInput, RunAuditEventFilter, ArchivedTaskEntry, ArchiveAgentLogMode, TaskPriority, SourceType, WorkflowStepTemplate, Agent, AutostashOrphanRecord, TaskCommitAssociation, TaskCommitAssociationMatchSource, TaskCommitAssociationConfidence, GithubIssueAction, MergeQueueEntry, MergeQueueEnqueueOptions, MergeQueueAcquireOptions, MergeQueueReleaseOutcome, HandoffToReviewOptions, GoalCitation, GoalCitationFilter, GoalCitationInput, GoalCitationSurface, BranchGroup, BranchGroupCreateInput, BranchGroupUpdate, TaskBranchAssignmentMode, MergeRequestRecord, MergeRequestState, CompletionHandoffMarker } from "./types.js";
 import { createActivityLogSnapshot, createRunAuditSnapshot, createTaskMetadataSnapshot, toTaskMetadataRecord, validateSnapshotEnvelope, type ActivityLogSnapshot, type RunAuditSnapshot, type TaskMetadataSnapshot } from "./shared-mesh-state.js";
-import { VALID_TRANSITIONS, DEFAULT_SETTINGS, isGlobalOnlySettingsKey, WORKFLOW_STEP_TEMPLATES, validateDocumentKey } from "./types.js";
+import { VALID_TRANSITIONS, COLUMNS, DEFAULT_SETTINGS, isGlobalOnlySettingsKey, WORKFLOW_STEP_TEMPLATES, validateDocumentKey } from "./types.js";
 import { DEFAULT_PROJECT_SETTINGS } from "./settings-schema.js";
 import { parseWorkflowIr, serializeWorkflowIr } from "./workflow-ir.js";
 import { isWorkflowColumnsEnabled } from "./workflow-columns-settings.js";
@@ -36,7 +36,12 @@ import {
   makeTransitionRejection,
   makeTransitionPending,
 } from "./transition-types.js";
-import { writeTransitionPending, clearTransitionPending } from "./transition-pending.js";
+import {
+  writeTransitionPending,
+  clearTransitionPending,
+  readTransitionPending,
+  reconcileHooksRemaining,
+} from "./transition-pending.js";
 import { BUILTIN_CODING_WORKFLOW_IR } from "./builtin-coding-workflow-ir.js";
 import type { WorkflowIr, WorkflowIrColumn } from "./workflow-ir-types.js";
 // Side-effect import: registers the 14 built-in trait DEFINITIONS into the
@@ -1604,6 +1609,15 @@ export class TaskStore extends EventEmitter<TaskStoreEvents> {
       const settings = await this.getSettingsFast();
       if (isWorkflowColumnsEnabled(settings)) {
         await this.runWorkflowColumnsIntegrityPass();
+        // #1401: recover any transitionPending markers stranded by a crash
+        // between the in-txn write and the post-commit clear (they otherwise
+        // permanently inflate capacity counts for their target column).
+        await this.recoverStaleTransitionPending();
+      } else {
+        // #1409: flag-OFF init — evacuate any card stuck in a non-legacy column
+        // (e.g. the flag was toggled OFF out-of-process while a card sat in a
+        // custom column) so the board stays listable and moves work.
+        await this.evacuateCustomColumnsToLegacy("flag-off-init");
       }
     } catch (err) {
       storeLog.warn("workflowColumns integrity pass failed during init", {
@@ -3369,6 +3383,20 @@ export class TaskStore extends EventEmitter<TaskStoreEvents> {
       const updatedMerged: Settings = { ...DEFAULT_SETTINGS, ...globalSettings, ...updatedProjectSettings } as Settings;
       this.emit("settings:updated", { settings: updatedMerged, previous: previousMerged });
 
+      // #1409: if this update flipped workflowColumns ON→OFF, evacuate any card
+      // stranded in a custom (non-legacy) column back to a legacy column so the
+      // board stays listable / movable on the legacy path.
+      if (isWorkflowColumnsEnabled(previousMerged) && !isWorkflowColumnsEnabled(updatedMerged)) {
+        try {
+          await this.evacuateCustomColumnsToLegacy("flag-toggled-off");
+        } catch (err) {
+          storeLog.warn("workflowColumns ON→OFF evacuation failed", {
+            phase: "evacuate-custom-columns",
+            error: err instanceof Error ? err.message : String(err),
+          });
+        }
+      }
+
       // Bootstrap project memory file when memory is toggled on
       if (updatedMerged.memoryEnabled !== false && previousMerged.memoryEnabled === false) {
         try {
@@ -3469,6 +3497,21 @@ export class TaskStore extends EventEmitter<TaskStoreEvents> {
 
     // Emit settings:updated so SSE listeners pick up the change
     this.emit("settings:updated", { settings: merged, previous });
+
+    // #1409: workflowColumns lives in experimentalFeatures (a global key), so the
+    // ON→OFF toggle flows through here. Evacuate any card stranded in a custom
+    // column when the flag flips off.
+    if (isWorkflowColumnsEnabled(previous) && !isWorkflowColumnsEnabled(merged)) {
+      try {
+        await this.evacuateCustomColumnsToLegacy("flag-toggled-off");
+      } catch (err) {
+        storeLog.warn("workflowColumns ON→OFF evacuation failed", {
+          phase: "evacuate-custom-columns",
+          error: err instanceof Error ? err.message : String(err),
+        });
+      }
+    }
+
     return merged;
   }
 
@@ -5839,7 +5882,18 @@ export class TaskStore extends EventEmitter<TaskStoreEvents> {
     if (useWorkflow && workflowIr) {
       // ── Flag-ON validation + sync guards (typed rejections, KTD-3/R13) ─────
       // 1. Target column must exist in the task's workflow → unknown-column.
-      if (!workflowHasColumn(workflowIr, toColumn)) {
+      //    #1411: a recoveryRehome move to a LEGACY column (todo/archived/…) is
+      //    the engine's self-healing rescue path — those targets are guaranteed
+      //    safe landing columns even when a custom workflow never defined them.
+      //    recoveryRehome already skips adjacency (below); it must likewise skip
+      //    the unknown-column rejection for legacy recovery targets, otherwise a
+      //    custom-workflow card could never be rescued to todo/archived and would
+      //    stay stuck — the exact bug #1411 describes. Non-legacy unknown targets
+      //    still reject (a genuine programming error), and normal (non-recovery)
+      //    moves are unaffected.
+      const recoveryToLegacy =
+        options?.recoveryRehome === true && (COLUMNS as readonly string[]).includes(toColumn);
+      if (!workflowHasColumn(workflowIr, toColumn) && !recoveryToLegacy) {
         throw new TransitionRejectionError(
           makeTransitionRejection(
             "unknown-column",
@@ -5932,12 +5986,26 @@ export class TaskStore extends EventEmitter<TaskStoreEvents> {
       // A task can sit in a custom column when the flag was toggled ON→OFF;
       // `VALID_TRANSITIONS` only keys the legacy columns, so a missing entry
       // degrades to the legacy "Invalid transition" error instead of a TypeError.
-      const validTargets = VALID_TRANSITIONS[task.column as Column] ?? [];
-      if (!validTargets.includes(toColumn)) {
-        throw new Error(
-          `Invalid transition: '${task.column}' → '${toColumn}'. ` +
-            `Valid targets: ${validTargets.join(", ") || "none"}`,
-        );
+      // #1409: flag-OFF evacuation. A recoveryRehome move OUT of a non-legacy
+      // (custom) column into a legacy target is the ON→OFF evacuation path —
+      // `VALID_TRANSITIONS` never keys a custom source column, so the legacy
+      // check below would strand the card forever. Allow it through (bypassing
+      // only the adjacency check; this is unreachable for normal flag-OFF moves,
+      // which never set recoveryRehome and always start from a legacy column, so
+      // characterization behavior is byte-identical).
+      const sourceIsLegacy = (COLUMNS as readonly string[]).includes(task.column);
+      const isEvacuation =
+        options?.recoveryRehome === true &&
+        !sourceIsLegacy &&
+        (COLUMNS as readonly string[]).includes(toColumn);
+      if (!isEvacuation) {
+        const validTargets = VALID_TRANSITIONS[task.column as Column] ?? [];
+        if (!validTargets.includes(toColumn)) {
+          throw new Error(
+            `Invalid transition: '${task.column}' → '${toColumn}'. ` +
+              `Valid targets: ${validTargets.join(", ") || "none"}`,
+          );
+        }
       }
 
       if (fromColumn === "in-review" && toColumn === "done" && !options?.skipMergeBlocker) {
@@ -12249,6 +12317,201 @@ ${stepsSection}`;
     return { scanned, rehomed, skippedTerminal };
   }
 
+  // ── #1401: transitionPending recovery sweep ───────────────────────────────
+  //
+  // A crash between the in-txn `transitionPending` marker write and the
+  // post-commit `clearTransitionPending` leaves the marker set forever. Because
+  // `countActiveInCapacitySlotSync` counts a pending marker as occupying a
+  // capacity slot for its `toColumn`, a stale marker permanently inflates that
+  // (workflow, column) capacity count. This sweep is the backstop the comments
+  // across store.ts / merge-trait.ts / transition-pending.ts reference: it scans
+  // every task carrying a non-null marker, reconciles `hooksRemaining` against
+  // the currently-known hook set, re-runs the surviving idempotent post-commit
+  // hooks via the same runner the live path uses, audits the recovery, and
+  // clears the marker so the reserved capacity slot is released.
+  //
+  // Idempotent: the default-workflow field effects already committed in-lock, so
+  // re-running them is a no-op, and a second sweep finds no markers. Plugin hooks
+  // are re-derived from the resolved IR (so an uninstalled-plugin hook simply
+  // drops, surfaced as an audit warning) and are expected to be idempotent per
+  // KTD-2. Runs at store init (alongside the integrity pass) and periodically
+  // from the flag-ON sweep cadence.
+  async recoverStaleTransitionPending(): Promise<{ scanned: number; recovered: number; degradedHooks: number }> {
+    let scanned = 0;
+    let recovered = 0;
+    let degradedHooks = 0;
+
+    const rows = this.db
+      .prepare(
+        `SELECT id FROM tasks WHERE transitionPending IS NOT NULL AND transitionPending != '' AND deletedAt IS NULL`,
+      )
+      .all() as Array<{ id: string }>;
+
+    // The set of hook ids the current process can still honor: the always-present
+    // default-workflow post-commit marker plus every registered plugin trait's
+    // onEnter/onExit hook. A marker entry not in this set belongs to an
+    // uninstalled plugin and is dropped (audited) rather than re-run.
+    const registry = getTraitRegistry();
+    const knownHookIds = new Set<string>(["default-workflow:postCommit"]);
+    for (const def of registry.listTraits()) {
+      if (def.hooks?.onEnter) knownHookIds.add(`${def.id}:onEnter`);
+      if (def.hooks?.onExit) knownHookIds.add(`${def.id}:onExit`);
+    }
+
+    for (const { id } of rows) {
+      scanned += 1;
+      const marker = readTransitionPending(this.db, id);
+      // null = nothing pending (corrupt/empty marker degrades to settled); we
+      // still clear the stored column so the slot is released. undefined = row
+      // vanished mid-sweep — skip.
+      if (marker === undefined) continue;
+
+      await this.withTaskLock(id, async () => {
+        // Re-read inside the lock: another path may have cleared it already.
+        const live = readTransitionPending(this.db, id);
+        if (live == null) {
+          // Corrupt/empty marker — clear the stored value defensively so it stops
+          // counting against capacity, then move on.
+          if (live === null) {
+            try {
+              clearTransitionPending(this.db, id);
+            } catch {
+              // best-effort
+            }
+          }
+          return;
+        }
+
+        const { hooksRemaining, warnings } = reconcileHooksRemaining(live.hooksRemaining, knownHookIds);
+        degradedHooks += warnings.length;
+
+        // Re-run the surviving idempotent post-commit hooks. The default-workflow
+        // field effects already committed in-lock pre-crash, so the only work that
+        // can still be owed is the plugin trait hook runner, which re-derives its
+        // pending set from the resolved IR and is idempotent (KTD-2). We invoke it
+        // only when a plugin hook entry survived (a marker carrying just
+        // `default-workflow:postCommit` needs no re-run — just a clear).
+        const hasSurvivingPluginHook = hooksRemaining.some((h) => h !== "default-workflow:postCommit");
+        if (hasSurvivingPluginHook) {
+          const task = this.readTaskFromDb(id, { includeDeleted: false });
+          if (task) {
+            const ir = this.resolveTaskWorkflowIrSync(id);
+            // fromColumn is unknown post-crash; the marker only records toColumn.
+            // The hook runner keys onEnter off toColumn (and onExit off fromColumn);
+            // re-running onEnter for the destination is the recoverable, idempotent
+            // half. Use the task's current column as fromColumn (it committed to
+            // toColumn at marker-write time, so current == toColumn and onExit is a
+            // no-op, which is correct — we never re-fire an exit we may have run).
+            try {
+              await this.runPluginColumnTransitionHooks(id, ir, task.column, live.toColumn);
+            } catch (err) {
+              storeLog.warn("transitionPending recovery: hook re-run faulted (degraded)", {
+                phase: "recover-stale-transition-pending",
+                taskId: id,
+                error: err instanceof Error ? err.message : String(err),
+              });
+            }
+          }
+        }
+
+        for (const warning of warnings) {
+          storeLog.warn(warning, {
+            phase: "recover-stale-transition-pending",
+            taskId: id,
+          });
+        }
+
+        // Clear the marker — releases the reserved capacity slot.
+        try {
+          clearTransitionPending(this.db, id);
+        } catch {
+          // best-effort; a later sweep retries.
+        }
+
+        this.recordRunAuditEvent({
+          taskId: id,
+          agentId: "system",
+          runId: `transition-pending-recovery-${id}-${Date.now()}`,
+          domain: "database",
+          mutationType: "task:transition-pending-recovered",
+          target: id,
+          metadata: {
+            toColumn: live.toColumn,
+            hooksReran: hooksRemaining,
+            droppedHooks: warnings.length,
+            startedAt: live.startedAt,
+          },
+        });
+        recovered += 1;
+      });
+    }
+
+    if (recovered > 0 || degradedHooks > 0) {
+      storeLog.log("transitionPending recovery sweep completed", {
+        phase: "recover-stale-transition-pending",
+        scanned,
+        recovered,
+        degradedHooks,
+      });
+    }
+    return { scanned, recovered, degradedHooks };
+  }
+
+  // ── #1409: flag ON→OFF evacuation ─────────────────────────────────────────
+  //
+  // When `workflowColumns` is disabled (or at flag-OFF store init), the board
+  // reverts to the legacy enum/`VALID_TRANSITIONS` path, where only the legacy
+  // {@link COLUMNS} are valid. Any card sitting in a CUSTOM (non-legacy) column
+  // would be stuck: it can't be listed/moved through the legacy path. This pass
+  // detects those cards and re-homes each to the nearest legacy column — the
+  // default workflow's entry column (`todo`) — via the existing recovery-rehome
+  // path (engine source + bypassGuards + recoveryRehome, capacity-honoring),
+  // auditing one event per card. Terminal cards (done/archived) are left put.
+  //
+  // Idempotent: a second run finds every card in a legacy column and is a no-op.
+  async evacuateCustomColumnsToLegacy(
+    trigger: "flag-off-init" | "flag-toggled-off",
+  ): Promise<{ scanned: number; evacuated: number }> {
+    let scanned = 0;
+    let evacuated = 0;
+
+    const legacyColumns = new Set<string>(COLUMNS);
+    // Nearest legacy landing column: the default workflow's entry column
+    // (triage). Falls back to "triage" defensively if the IR can't be resolved.
+    const targetColumn = resolveEntryColumnId(BUILTIN_CODING_WORKFLOW_IR) ?? "triage";
+
+    const rows = this.db
+      .prepare(`SELECT id, "column" AS col FROM tasks WHERE deletedAt IS NULL`)
+      .all() as Array<{ id: string; col: string }>;
+
+    for (const { id, col } of rows) {
+      scanned += 1;
+      // Already in a legacy column (the common case) — nothing to evacuate.
+      if (legacyColumns.has(col)) continue;
+      // Never disturb terminal cards (legacy terminal semantics — these column
+      // ids are never legacy here, but guard defensively for parity with the
+      // integrity pass).
+      if (col === "done" || col === "archived") continue;
+
+      await this.rehomeOccupant(id, targetColumn, "workflow-edit-rehome", {
+        evacuation: true,
+        trigger,
+        invalidColumn: col,
+      });
+      evacuated += 1;
+    }
+
+    if (evacuated > 0) {
+      storeLog.log("workflowColumns ON→OFF evacuation completed", {
+        phase: "evacuate-custom-columns",
+        trigger,
+        scanned,
+        evacuated,
+      });
+    }
+    return { scanned, evacuated };
+  }
+
   // ── Workflow selection (resolves a workflow to enabledWorkflowSteps) ────
   //
   // Selection never touches the engine's scheduler/executor/merger. It compiles
diff --git a/packages/engine/src/__tests__/self-healing-custom-workflow-recovery.test.ts b/packages/engine/src/__tests__/self-healing-custom-workflow-recovery.test.ts
new file mode 100644
index 0000000000..8fc16d54e0
--- /dev/null
+++ b/packages/engine/src/__tests__/self-healing-custom-workflow-recovery.test.ts
@@ -0,0 +1,124 @@
+// @vitest-environment node
+//
+// #1411: self-healing recovery/backward moves on CUSTOM workflows must pass
+// `recoveryRehome: true` (not rely on `bypassGuards`, which skips trait guards
+// but NOT order-derived column-graph adjacency). A custom workflow whose
+// order-derived adjacency lacks the custom-column → todo edge would otherwise
+// reject the recovery move and strand the card.
+//
+// This exercises a REAL TaskStore (flag-ON) so the in-lock adjacency check
+// (resolveAllowedColumns) actually runs:
+//   - a backward recovery move WITHOUT recoveryRehome (engine source +
+//     bypassGuards) is rejected by adjacency, proving bypassGuards alone is
+//     insufficient (the bug),
+//   - the SAME move WITH recoveryRehome: true succeeds (the fix self-healing
+//     now applies at its moveTask call sites).
+
+import { describe, it, expect, beforeEach, afterEach, vi } from "vitest";
+import { mkdtempSync, rmSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { execSync } from "node:child_process";
+import { TaskStore, type WorkflowIr } from "@fusion/core";
+
+function git(cwd: string, args: string): void {
+  execSync(`git ${args}`, { cwd, stdio: "ignore" });
+}
+
+function setColumn(store: TaskStore, taskId: string, column: string): void {
+  const db = (store as unknown as { db: { prepare: (s: string) => { run: (...a: unknown[]) => unknown } } }).db;
+  db.prepare('UPDATE tasks SET "column" = ?, "columnMovedAt" = ? WHERE id = ?').run(
+    column,
+    new Date().toISOString(),
+    taskId,
+  );
+}
+
+/**
+ * A custom workflow whose linear order is intake → build → done. Its
+ * order-derived adjacency has NO edge build → todo (todo is not even a column),
+ * so a recovery move build → todo is only reachable via recoveryRehome.
+ */
+function customIr(): WorkflowIr {
+  return {
+    version: "v2",
+    name: "linear-custom",
+    columns: [
+      { id: "intake", name: "intake", traits: [{ trait: "intake" }] },
+      { id: "build", name: "build", traits: [] },
+      { id: "done", name: "done", traits: [{ trait: "complete" }] },
+    ],
+    nodes: [
+      { id: "start", kind: "start", column: "intake" },
+      { id: "work", kind: "prompt", column: "build", config: { prompt: "do" } },
+      { id: "end", kind: "end", column: "done" },
+    ],
+    edges: [
+      { from: "start", to: "work", condition: "success" },
+      { from: "work", to: "end", condition: "success" },
+    ],
+  } as WorkflowIr;
+}
+
+describe("#1411 self-healing recovery move on custom workflows", () => {
+  let rootDir = "";
+  let store: TaskStore;
+
+  beforeEach(async () => {
+    rootDir = mkdtempSync(join(tmpdir(), "fn-1411-"));
+    git(rootDir, "init -b main");
+    git(rootDir, "config user.name 'Fusion'");
+    git(rootDir, "config user.email 'hi@runfusion.ai'");
+    writeFileSync(join(rootDir, "README.md"), "root\n");
+    git(rootDir, "add README.md");
+    git(rootDir, "commit -m init");
+    store = new TaskStore(rootDir, undefined, { inMemoryDb: false });
+    await store.init();
+    await store.updateGlobalSettings({ experimentalFeatures: { workflowColumns: true } });
+  });
+
+  afterEach(() => {
+    try { store?.close(); } catch { /* ignore */ }
+    if (rootDir) rmSync(rootDir, { recursive: true, force: true });
+    vi.clearAllMocks();
+  });
+
+  async function seedCardInBuild(): Promise<string> {
+    const wf = await store.createWorkflowDefinition({ name: "linear-custom", ir: customIr() });
+    const task = await store.createTask({ description: "stuck-in-build" });
+    await store.selectTaskWorkflowAndReconcile(task.id, wf.id);
+    setColumn(store, task.id, "build");
+    expect((await store.getTask(task.id)).column).toBe("build");
+    return task.id;
+  }
+
+  it("bypassGuards alone is rejected by order-derived adjacency (build → todo)", async () => {
+    const id = await seedCardInBuild();
+    let caught: unknown;
+    try {
+      // Mirrors a self-healing backward move BEFORE the fix: engine source +
+      // bypassGuards, but no recoveryRehome. Adjacency (build → todo) has no edge.
+      await store.moveTask(id, "todo", { moveSource: "engine", bypassGuards: true, preserveProgress: true });
+    } catch (e) {
+      caught = e;
+    }
+    expect(caught).toBeInstanceOf(Error);
+    expect((await store.getTask(id)).column).toBe("build");
+  });
+
+  it("recoveryRehome: true lets the recovery move reach todo (the fix)", async () => {
+    const id = await seedCardInBuild();
+    await store.moveTask(id, "todo", {
+      moveSource: "engine",
+      recoveryRehome: true,
+      preserveProgress: true,
+    });
+    expect((await store.getTask(id)).column).toBe("todo");
+  });
+
+  it("recoveryRehome: true also reaches a terminal recovery target (archived)", async () => {
+    const id = await seedCardInBuild();
+    await store.moveTask(id, "archived", { moveSource: "engine", recoveryRehome: true });
+    expect((await store.getTask(id)).column).toBe("archived");
+  });
+});
diff --git a/packages/engine/src/self-healing.ts b/packages/engine/src/self-healing.ts
index 500edfe0fc..55c603a4d9 100644
--- a/packages/engine/src/self-healing.ts
+++ b/packages/engine/src/self-healing.ts
@@ -28,7 +28,7 @@ import { promisify } from "node:util";
 import { setImmediate as setImmediateCb } from "node:timers";
 import { existsSync, mkdirSync, readdirSync, readFileSync, realpathSync, rmSync, statSync, writeFileSync } from "node:fs";
 import { isAbsolute, join, relative, resolve } from "node:path";
-import { IN_REVIEW_STALL_DEADLOCK_LOG_PREFIX, IN_REVIEW_STALL_LOG_PREFIX, allowsAutoMergeProcessing, countRecentIdenticalStallEntries, detectDependencyCycle, detectSelfDefeatingDependency, getInReviewStalledSignal, getInReviewStallReason, getPrimaryPrInfo, getStalePausedReviewSignal, getStalePausedTodoSignal, getTaskHardMergeBlocker, getTaskMergeBlocker, isEphemeralAgent, isMergeRequestContractShadowEnabled, isSharedBranchGroupMemberIntegration, parseExplicitDuplicateMarker, type AgentStore, type ChatStore, type MessageStore, type TaskStore, type Settings, type Task, type MergeDetails, type TaskPriority, type MergeResult } from "@fusion/core";
+import { IN_REVIEW_STALL_DEADLOCK_LOG_PREFIX, IN_REVIEW_STALL_LOG_PREFIX, allowsAutoMergeProcessing, countRecentIdenticalStallEntries, detectDependencyCycle, detectSelfDefeatingDependency, getInReviewStalledSignal, getInReviewStallReason, getPrimaryPrInfo, getStalePausedReviewSignal, getStalePausedTodoSignal, getTaskHardMergeBlocker, getTaskMergeBlocker, isEphemeralAgent, isMergeRequestContractShadowEnabled, isWorkflowColumnsEnabled, isSharedBranchGroupMemberIntegration, parseExplicitDuplicateMarker, type AgentStore, type ChatStore, type MessageStore, type TaskStore, type Settings, type Task, type MergeDetails, type TaskPriority, type MergeResult } from "@fusion/core";
 import type { MeshLeaseManager } from "./mesh-lease-manager.js";
 import { createLogger, schedulerLog } from "./logger.js";
 import { RemovalReason, classifyTaskWorktree, getRegisteredWorktreeBranchMap, getRegisteredWorktreePaths, isUsableTaskWorktree, removeWorktree, resolveWorktreeBackend, scanIdleWorktrees, scanOrphanedBranches } from "./worktree-pool.js";
@@ -110,7 +110,9 @@ export async function archiveAsGhostBug(
       findings: decision.findings.slice(0, 10),
     },
   });
-  await store.moveTask(taskId, "archived");
+  // #1411: recovery/terminal move — recoveryRehome skips order-derived adjacency
+  // so a custom-workflow card can always reach the terminal column.
+  await store.moveTask(taskId, "archived", { moveSource: "engine", recoveryRehome: true });
 }
 
 async function classifyOwnedLandedEvidenceForSelfHealing(rootDir: string, task: Task, mergeTargetBranch: string): Promise<OwnedLandedClassification> {
@@ -437,9 +439,10 @@ export async function autoRecoverWorktreeSessionStartFailure(
         : `Auto-recovered: retry/verification session targeted unusable worktree${staleWorktree ? ` (${staleWorktree})` : ""} — cleared stale session metadata and requeued to todo (attempt ${nextCount}/${MAX_WORKTREE_SESSION_RETRIES}, failure: ${failureExcerpt})`,
   );
   if (noProgress) {
-    await store.moveTask(task.id, "todo");
+    // #1411: backward recovery move — recoveryRehome skips order-derived adjacency.
+    await store.moveTask(task.id, "todo", { moveSource: "engine", recoveryRehome: true });
   } else {
-    await store.moveTask(task.id, "todo", { preserveProgress: true });
+    await store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine", recoveryRehome: true });
   }
   return { outcome: "requeue-todo", retries: nextCount, classification };
 }
@@ -1112,6 +1115,9 @@ export class SelfHealingManager {
             await this.store.moveTask(taskId, "todo", {
               preserveProgress: true,
               preserveStatus: true,
+              // #1411: backward recovery — skip order-derived adjacency.
+              moveSource: "engine",
+              recoveryRehome: true,
             });
           } catch (moveErr: unknown) {
             const moveErrMessage = moveErr instanceof Error ? moveErr.message : String(moveErr);
@@ -1768,6 +1774,10 @@ export class SelfHealingManager {
           { name: "auto-archive-meta-resolved", fn: () => this.autoArchiveResolvedMetaTasks() },
           { name: "auto-archive-meta-stalled", fn: () => this.autoArchiveStalledMetaTasks() },
           { name: "board-stall-auto-recovery", fn: () => this.runBoardStallAutoRecoverySweep() },
+          // #1401: periodically recover transitionPending markers stranded by a
+          // crash between the in-txn write and the post-commit clear (flag-ON
+          // only; a no-op when there are no markers).
+          { name: "recover-stale-transition-pending", fn: () => this.runStaleTransitionPendingSweep() },
           { name: "reconcile-self-defeating-deps", fn: () => this.reconcileSelfDefeatingDependencies() },
           { name: "reconcile-dependency-cycles", fn: () => this.reconcileDependencyCycles().then(() => undefined) },
           { name: "reclaim-pr-conflicts", fn: () => this.reclaimPrConflicts() },
@@ -2200,6 +2210,8 @@ export class SelfHealingManager {
           });
           await this.store.moveTask(task.id, "todo", {
             moveSource: "engine",
+            // #1411: backward recovery — skip order-derived adjacency.
+            recoveryRehome: true,
             preserveWorktree: true,
             preserveProgress: true,
             preserveResumeState: true,
@@ -2467,6 +2479,8 @@ export class SelfHealingManager {
                 } else {
                   await this.store.moveTask(task.id, "todo", {
                     moveSource: "engine",
+                    // #1411: backward recovery — skip order-derived adjacency.
+                    recoveryRehome: true,
                     preserveProgress: true,
                     preserveResumeState: true,
                   });
@@ -2570,6 +2584,8 @@ export class SelfHealingManager {
                   } else {
                     await this.store.moveTask(task.id, "todo", {
                       moveSource: "engine",
+                      // #1411: backward recovery — skip order-derived adjacency.
+                      recoveryRehome: true,
                       preserveProgress: true,
                       preserveResumeState: true,
                     });
@@ -2637,6 +2653,8 @@ export class SelfHealingManager {
             const idleMs = Number.isFinite(idleAnchorMs) ? Math.max(0, Date.now() - idleAnchorMs) : null;
             await this.store.moveTask(task.id, "todo", {
               moveSource: "engine",
+              // #1411: backward recovery — skip order-derived adjacency.
+              recoveryRehome: true,
               preserveWorktree: true,
               preserveProgress: true,
               preserveResumeState: true,
@@ -2703,6 +2721,8 @@ export class SelfHealingManager {
             } else {
               await this.store.moveTask(task.id, "todo", {
                 moveSource: "engine",
+                // #1411: backward recovery — skip order-derived adjacency.
+                recoveryRehome: true,
                 preserveWorktree: true,
                 preserveProgress: true,
                 preserveResumeState: true,
@@ -3621,6 +3641,8 @@ export class SelfHealingManager {
         preserveWorktree: true,
         preserveResumeState: true,
         moveSource: "engine",
+        // #1411: backward recovery — skip order-derived adjacency.
+        recoveryRehome: true,
       });
       await this.store.logEntry(
         task.id,
@@ -3886,6 +3908,19 @@ export class SelfHealingManager {
     return archived;
   }
 
+  /**
+   * #1401: periodic transitionPending recovery sweep. Flag-ON only — when
+   * `workflowColumns` is OFF the legacy path never writes markers, so there is
+   * nothing to recover. Delegates to the store's idempotent recovery method
+   * (a no-op when no stale markers exist), keeping capacity counts honest after
+   * a crash between the in-txn marker write and the post-commit clear.
+   */
+  async runStaleTransitionPendingSweep(): Promise<void> {
+    const settings = await this.store.getSettings();
+    if (!isWorkflowColumnsEnabled(settings)) return;
+    await this.store.recoverStaleTransitionPending();
+  }
+
   async runBoardStallAutoRecoverySweep(): Promise<{ holders: string[]; recovered: number; unrecovered: boolean }> {
     const settings = await this.store.getSettings();
     const windowMs = Number(settings.boardStallSweepWindowMs ?? 2 * 60 * 60_000);
@@ -4616,7 +4651,8 @@ export class SelfHealingManager {
             await this.emitBackwardMoveNoAction(task, "finalize-no-op-review", "task:finalize-no-op-review-no-action", proof);
             continue;
           }
-          await this.store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine" });
+          // #1411: backward recovery — skip order-derived adjacency.
+          await this.store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine", recoveryRehome: true });
           continue;
         }
 
@@ -4666,7 +4702,8 @@ export class SelfHealingManager {
               classification: "proven-no-op",
               baseRef: classification.baseRef,
             });
-            await this.store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine" });
+            // #1411: backward recovery — skip order-derived adjacency.
+            await this.store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine", recoveryRehome: true });
             recovered++;
             continue;
           }
@@ -5102,7 +5139,8 @@ export class SelfHealingManager {
             task.id,
             "Auto-recovered: in-review task still had incomplete steps — moved back to todo for retry",
           );
-          await this.store.moveTask(task.id, "todo", { preserveProgress: true });
+          // #1411: backward recovery — skip order-derived adjacency.
+          await this.store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine", recoveryRehome: true });
           log.log(`Recovered stale incomplete review task ${task.id}: moved back to todo`);
           recovered++;
         } catch (err: unknown) { const errorMessage = err instanceof Error ? err.message : String(err);
@@ -5506,7 +5544,8 @@ export class SelfHealingManager {
             task.id,
             "Auto-recovered: in-review task idle past stuck-task timeout — kicked back to todo",
           );
-          await this.store.moveTask(task.id, "todo", { preserveProgress: true });
+          // #1411: backward recovery — skip order-derived adjacency.
+          await this.store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine", recoveryRehome: true });
           log.log(`Kicked ghost review task ${task.id} back to todo`);
           recovered++;
         } catch (err: unknown) {
@@ -7248,7 +7287,8 @@ export class SelfHealingManager {
               stepStatuses,
             },
           });
-          await this.store.moveTask(task.id, "todo", { preserveProgress: true });
+          // #1411: backward recovery — skip order-derived adjacency.
+          await this.store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine", recoveryRehome: true });
           recovered++;
         } catch (err: unknown) {
           const errorMessage = err instanceof Error ? err.message : String(err);
@@ -7785,7 +7825,8 @@ export class SelfHealingManager {
             task.id,
             "Auto-recovered no-progress no-task_done failure — clean worktree, moved back to todo",
           );
-          await this.store.moveTask(task.id, "todo");
+          // #1411: backward recovery — skip order-derived adjacency.
+          await this.store.moveTask(task.id, "todo", { moveSource: "engine", recoveryRehome: true });
           recovered++;
         } catch (err: unknown) { const errorMessage = err instanceof Error ? err.message : String(err);
           log.error(`Failed to recover no-progress no-task_done failure ${task.id}: ${errorMessage}`);
@@ -7952,7 +7993,8 @@ export class SelfHealingManager {
             task.id,
             `Auto-retry ${nextCount}/${MAX_TASK_DONE_RETRIES}: agent finished without fn_task_done — requeuing to todo to resume partial work`,
           );
-          await this.store.moveTask(task.id, "todo", { preserveProgress: true });
+          // #1411: backward recovery — skip order-derived adjacency.
+          await this.store.moveTask(task.id, "todo", { preserveProgress: true, moveSource: "engine", recoveryRehome: true });
           recovered++;
         } catch (err: unknown) {
           const errorMessage = err instanceof Error ? err.message : String(err);