diff --git a/.changeset/detail-modal-canonical-flags.md b/.changeset/detail-modal-canonical-flags.md
new file mode 100644
index 0000000000..6d904ff253
--- /dev/null
+++ b/.changeset/detail-modal-canonical-flags.md
@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": patch
+---
+
+summary: The duplicate-warning banner in Task Detail now judges the canonical by its own lane, not the legacy ids.
+category: fix
+dev: `isNearDuplicateCanonicalInactive` in TaskDetailModal now receives `columnFlagsByTaskId.get(canonical.id)`; the allow-list entry claiming this needed a fetch is removed.
diff --git a/packages/dashboard/app/components/TaskDetailModal.tsx b/packages/dashboard/app/components/TaskDetailModal.tsx
index bb466151c3..d953c94c4c 100644
--- a/packages/dashboard/app/components/TaskDetailModal.tsx
+++ b/packages/dashboard/app/components/TaskDetailModal.tsx
@@ -944,15 +944,31 @@ export function TaskDetailContent({
   vs union confusion that `column-role-degraded-flags.test.ts` exists to catch, and it would type-check
   and read as a conversion.
 
-  Supplying it correctly needs the canonical's own resolved flags, which means fetching them: a data
-  change, out of scope here. So the omission is deliberate and is exempted BY CALL SITE rather than by
-  function name, so core's sibling site stays guarded.
+  FNXC:WorkflowResolvedColumns 2026-07-31-03:10 (the "needs a fetch" blocker was never tested):
+  The paragraph above rejected passing `detailColumnFlags` — correctly, that would answer about the
+  wrong task — and then concluded the seam needs a data change. It does not. `columnFlagsByTaskId` is
+  already a prop of this component (declared :367, destructured :727, used for the fan-out map), and
+  it is keyed by task id. The canonical is `tasks.find(c => c.id === nearDuplicateOf)`, so it is
+  drawn from the same loaded set the map covers — a `.get(canonical.id)` is the canonical's OWN
+  flags, with no fetch.
+
+  `Column.tsx:307` already does exactly this, with a comment making the same point about not reusing
+  the row's flags. The blocker was asserted from the shape of the problem (two different tasks) rather
+  than tested against what was in scope.
+
+  A canonical the map does not cover yields `undefined`, which is the documented legacy fallback —
+  strictly better than always-legacy, never a fabricated answer.
   */
   const showNearDuplicateWarning = Boolean(nearDuplicateOf)
     && workingTask.sourceMetadata?.nearDuplicateDismissed !== true
     && task.column !== "archived"
     && task.column !== "done"
-    && !isNearDuplicateCanonicalInactive(nearDuplicateCanonical);
+    && !isNearDuplicateCanonicalInactive(
+      nearDuplicateCanonical,
+      /* The CANONICAL's own flags, keyed by its id — never `detailColumnFlags`, which describes this
+         modal's task. Same shape as Column.tsx:307, the sibling site that already does this. */
+      nearDuplicateCanonical ? columnFlagsByTaskId?.get(nearDuplicateCanonical.id) : undefined,
+    );
   const [sourceAgent, setSourceAgent] = useState<Agent | null>(null);
   const [selectedSourceAgentId, setSelectedSourceAgentId] = useState<string | null>(null);
   const provenanceDisplay = getProvenanceLabel(workingTask, {
diff --git a/scripts/check-inert-flag-seams.mjs b/scripts/check-inert-flag-seams.mjs
index bbd458d1bd..67a68e007c 100644
--- a/scripts/check-inert-flag-seams.mjs
+++ b/scripts/check-inert-flag-seams.mjs
@@ -150,12 +150,6 @@ const ALLOWED_OMISSIONS = new Map([
       + "change, not local wiring, which is the same 'needs a data change' category as the entry below. "
       + "Filed for the plugin-API owner rather than bodged here." },
   ],
-  [
-    "packages/dashboard/app/components/TaskDetailModal.tsx::isNearDuplicateCanonicalInactive",
-    { count: 1, reason: "The flags in scope describe the MODAL'S task; the canonical is a different task on a column this "
-      + "component never resolves. Passing them would type-check, read as a conversion, and answer "
-      + "about the wrong task. Correct supply needs a fetch — a data change. See the note at the site." },
-  ],
 ]);
 
 /*
diff --git a/scripts/lib/lane-wiring-baseline.json b/scripts/lib/lane-wiring-baseline.json
index 16187a1ec9..1e631f0633 100644
--- a/scripts/lib/lane-wiring-baseline.json
+++ b/scripts/lib/lane-wiring-baseline.json
@@ -10,7 +10,6 @@
     "packages/dashboard/src/routes/register-task-workflow-routes.ts": 1,
     "packages/dashboard/app/components/Lane.tsx": 1,
     "packages/dashboard/app/components/ListView.tsx": 1,
-    "packages/dashboard/app/components/TaskDetailModal.tsx": 1,
     "packages/dashboard/app/hooks/useBlockerFanout.ts": 1,
     "packages/cli/src/commands/dashboard-tui/app.tsx": 1,
     "packages/cli/src/commands/dashboard-tui/bucket-mapping.ts": 1,