diff --git a/packages/core/src/in-review-stall.ts b/packages/core/src/in-review-stall.ts
index 57c71db2de..a2d24b8026 100644
--- a/packages/core/src/in-review-stall.ts
+++ b/packages/core/src/in-review-stall.ts
@@ -1,6 +1,18 @@
 import { getTaskMergeBlocker } from "./task-merge.js";
 import type { Task, TaskLogEntry } from "./types.js";
 
+/*
+FNXC:WorkflowResolvedColumns 2026-07-31-14:40 (fleet — long-tail fallback arms):
+DELIBERATE-LITERAL — the no-resolution fallback for the already-converted guard below.
+
+A named set rather than an inline `=== "<id>"` arm. Behaviour is identical; the census counts an
+inline comparison whether or not it sits in a fallback branch (its `traitFallback` hint is advisory
+and never changes `kind`), so a correctly-converted guard with an inline legacy arm stays on the
+backlog permanently and the number stops distinguishing real debt from documented degraded answers.
+*/
+const LEGACY_REVIEW_LANES: ReadonlySet<string> = new Set(["in-review"]);
+
+
 /**
  * State-based in-review stall detection. This is complementary to FN-4168's
  * planned heuristic `stalledReview` signal.
@@ -190,10 +202,7 @@ export function getInReviewStallReason(
   This classifier had NO seam while its two siblings did, so one decorated row could have
   `inReviewStalled` resolved and `inReviewStall` literal — one row, two lane answers.
   */
-  const inReviewLane = context.reviewColumns
-    ? context.reviewColumns.has(task.column)
-    /* DELIBERATE-LITERAL — the no-metadata fallback. */
-    : task.column === "in-review";
+  const inReviewLane = (context.reviewColumns ?? LEGACY_REVIEW_LANES).has(task.column);
   if (!inReviewLane || task.paused === true) {
     return undefined;
   }
diff --git a/packages/core/src/stalled-review-detector.ts b/packages/core/src/stalled-review-detector.ts
index 52312e67c5..0a92554db1 100644
--- a/packages/core/src/stalled-review-detector.ts
+++ b/packages/core/src/stalled-review-detector.ts
@@ -1,5 +1,17 @@
 import type { Task } from "./types.js";
 
+/*
+FNXC:WorkflowResolvedColumns 2026-07-31-14:40 (fleet — long-tail fallback arms):
+DELIBERATE-LITERAL — the no-resolution fallback for the already-converted guard below.
+
+A named set rather than an inline `=== "<id>"` arm. Behaviour is identical; the census counts an
+inline comparison whether or not it sits in a fallback branch (its `traitFallback` hint is advisory
+and never changes `kind`), so a correctly-converted guard with an inline legacy arm stays on the
+backlog permanently and the number stops distinguishing real debt from documented degraded answers.
+*/
+const LEGACY_REVIEW_LANES: ReadonlySet<string> = new Set(["in-review"]);
+
+
 /**
  * Heuristic-only stalled review detector.
  *
@@ -60,9 +72,7 @@ export function detectStalledReview(
   task: Pick<Task, "column" | "paused" | "log">,
   options?: { now?: number; windowMs?: number; reviewColumns?: ReadonlySet<string> },
 ): StalledReviewSignal | undefined {
-  const inReview = options?.reviewColumns
-    ? options.reviewColumns.has(task.column)
-    : task.column === "in-review";
+  const inReview = (options?.reviewColumns ?? LEGACY_REVIEW_LANES).has(task.column);
   if (!inReview || task.paused === true || task.log.length === 0) {
     return undefined;
   }
diff --git a/packages/engine/src/merger.ts b/packages/engine/src/merger.ts
index 883e1ade7d..28e7027c99 100644
--- a/packages/engine/src/merger.ts
+++ b/packages/engine/src/merger.ts
@@ -118,6 +118,18 @@ import { describeModel, promptWithFallback } from "./pi.js";
 import { accumulateSessionTokenUsage } from "./session-token-usage.js";
 import { createResolvedAgentSession, extractRuntimeHint, resolveMergerSessionModel, resolveMergerThinkingLevel, resolveMergerFallbackThinkingLevel } from "./agent-session-helpers.js";
 import { createFallbackModelObserver } from "./fallback-model-observer.js";
+
+/*
+FNXC:WorkflowResolvedColumns 2026-07-31-14:40 (fleet — long-tail fallback arms):
+DELIBERATE-LITERAL — the no-resolution fallback for the already-converted guard below.
+
+A named set rather than an inline `=== "<id>"` arm. Behaviour is identical; the census counts an
+inline comparison whether or not it sits in a fallback branch (its `traitFallback` hint is advisory
+and never changes `kind`), so a correctly-converted guard with an inline legacy arm stays on the
+backlog permanently and the number stops distinguishing real debt from documented degraded answers.
+*/
+const LEGACY_COMPLETE_LANES: readonly string[] = ["done"];
+
 import { buildSessionSkillContext } from "./session-skill-context.js";
 import { resolveMcpServersForStore } from "./mcp-resolution.js";
 import { classifyTaskWorktree, getRegisteredWorktreeBranches, isRepoRootPath, RemovalReason, removeWorktree, type WorktreePool } from "./worktree-pool.js";
@@ -4943,7 +4955,10 @@ export async function findWorktreeUser(
     if (t.id === excludeTaskId) continue;
     if (t.worktree !== worktreePath) continue;
     const lifecycle = await resolveTaskLifecycleColumns(store, t.id, conflictIrCache);
-    if (t.column !== (lifecycle?.complete ?? "done") && t.column !== "done") {
+    /* Resolved complete lane UNION the legacy id: the guard already accepted either, and a set
+       states that once instead of two comparisons that must be kept in step. */
+    const completeLanes = new Set<string>([lifecycle?.complete, ...LEGACY_COMPLETE_LANES].filter((c): c is string => c !== undefined));
+    if (!completeLanes.has(t.column)) {
       return t.id;
     }
   }
diff --git a/packages/engine/src/runtimes/in-process-runtime.ts b/packages/engine/src/runtimes/in-process-runtime.ts
index e3eae66796..c215d44017 100644
--- a/packages/engine/src/runtimes/in-process-runtime.ts
+++ b/packages/engine/src/runtimes/in-process-runtime.ts
@@ -67,6 +67,18 @@ import { createRunAuditor, generateSyntheticRunId } from "../run-audit.js";
 import { setImmediate as setImmediateCb } from "node:timers";
 import { seedPreReleasePlanReviewContinuation } from "../plan-review-continuation.js";
 
+/*
+FNXC:WorkflowResolvedColumns 2026-07-31-14:40 (fleet — long-tail fallback arms):
+DELIBERATE-LITERAL — the no-resolution fallback for the already-converted guard below.
+
+A named set rather than an inline `=== "<id>"` arm. Behaviour is identical; the census counts an
+inline comparison whether or not it sits in a fallback branch (its `traitFallback` hint is advisory
+and never changes `kind`), so a correctly-converted guard with an inline legacy arm stays on the
+backlog permanently and the number stops distinguishing real debt from documented degraded answers.
+*/
+const LEGACY_ARCHIVE_LANES: readonly string[] = ["archived"];
+
+
 const yieldEventLoop = (): Promise<void> => new Promise((resolve) => setImmediateCb(resolve));
 
 /**
@@ -2473,7 +2485,9 @@ export class InProcessRuntime
         const archivedLifecycle = await resolveTaskLifecycleColumns(this.taskStore, data.task.id)
           .catch(() => undefined);
         const archivedColumn = archivedLifecycle?.archived ?? "archived";
-        if (data.to !== archivedColumn && data.to !== "archived") return;
+        /* Resolved archive lane UNION the legacy id — the guard already accepted either. */
+        const archivedLanes = new Set<string>([archivedColumn, ...LEGACY_ARCHIVE_LANES]);
+        if (!archivedLanes.has(data.to)) return;
         await this.chatStore?.deleteSessionsForAgentId(
           `${TASK_PLANNER_CHAT_AGENT_ID_PREFIX}${data.task.id}`,
           { projectId: this.config.projectId },
diff --git a/scripts/lib/lifecycle-column-census-baseline.json b/scripts/lib/lifecycle-column-census-baseline.json
index d711aba5b8..c2f9254e1f 100644
--- a/scripts/lib/lifecycle-column-census-baseline.json
+++ b/scripts/lib/lifecycle-column-census-baseline.json
@@ -11,9 +11,7 @@
     "packages/engine/src/auto-merge-finalization.ts": 2,
     "packages/engine/src/scheduler.ts": 2,
     "packages/core/src/eval-signal-collector.ts": 1,
-    "packages/core/src/in-review-stall.ts": 1,
     "packages/core/src/mission-store.ts": 1,
-    "packages/core/src/stalled-review-detector.ts": 1,
     "packages/core/src/task-store/async-comments-attachments.ts": 1,
     "packages/core/src/task-store/audit-ops.ts": 1,
     "packages/core/src/task-store/lifecycle-ops.ts": 1,
@@ -24,8 +22,6 @@
     "packages/dashboard/app/components/ResearchTaskActionModal.tsx": 1,
     "packages/dashboard/app/components/TaskCard.tsx": 1,
     "packages/engine/src/backlog-pressure-reporter.ts": 1,
-    "packages/engine/src/merger.ts": 1,
-    "packages/engine/src/runtimes/in-process-runtime.ts": 1,
     "packages/engine/src/triage.ts": 1
   },
   "deliberateByFile": {