diff --git a/src/resources/extensions/gsd/auto-dispatch.ts b/src/resources/extensions/gsd/auto-dispatch.ts
index f7e50c2f2..85a79340c 100644
--- a/src/resources/extensions/gsd/auto-dispatch.ts
+++ b/src/resources/extensions/gsd/auto-dispatch.ts
@@ -12,7 +12,7 @@
 import type { GSDState } from "./types.js";
 import type { GSDPreferences } from "./preferences.js";
 import type { UatType } from "./files.js";
-import { loadFile, extractUatType, loadActiveOverrides } from "./files.js";
+import { loadFile, extractUatType, loadActiveOverrides, parseRoadmap } from "./files.js";
 import {
   resolveMilestoneFile, resolveMilestonePath, resolveSliceFile, resolveTaskFile,
   relSliceFile, buildMilestoneFileName,
@@ -123,6 +123,35 @@ const DISPATCH_RULES: DispatchRule[] = [
       };
     },
   },
+  {
+    name: "uat-verdict-gate (non-PASS blocks progression)",
+    match: async ({ mid, basePath, prefs }) => {
+      // Only applies when UAT dispatch is enabled
+      if (!prefs?.uat_dispatch) return null;
+
+      const roadmapFile = resolveMilestoneFile(basePath, mid, "ROADMAP");
+      const roadmapContent = roadmapFile ? await loadFile(roadmapFile) : null;
+      if (!roadmapContent) return null;
+
+      const roadmap = parseRoadmap(roadmapContent);
+      for (const slice of roadmap.slices.filter(s => s.done)) {
+        const resultFile = resolveSliceFile(basePath, mid, slice.id, "UAT-RESULT");
+        if (!resultFile) continue;
+        const content = await loadFile(resultFile);
+        if (!content) continue;
+        const verdictMatch = content.match(/verdict:\s*([\w-]+)/i);
+        const verdict = verdictMatch?.[1]?.toLowerCase();
+        if (verdict && verdict !== "pass" && verdict !== "passed") {
+          return {
+            action: "stop" as const,
+            reason: `UAT verdict for ${slice.id} is "${verdict}" — blocking progression until resolved.\nReview the UAT result and update the verdict to PASS, or re-run /gsd auto after fixing.`,
+            level: "warning" as const,
+          };
+        }
+      }
+      return null;
+    },
+  },
   {
     name: "reassess-roadmap (post-completion)",
     match: async ({ state, mid, midTitle, basePath, prefs }) => {
diff --git a/src/resources/extensions/gsd/auto-prompts.ts b/src/resources/extensions/gsd/auto-prompts.ts
index 6125e9470..67f963a0a 100644
--- a/src/resources/extensions/gsd/auto-prompts.ts
+++ b/src/resources/extensions/gsd/auto-prompts.ts
@@ -530,11 +530,21 @@ export async function checkNeedsRunUat(
   const uatContent = await loadFile(uatFile);
   if (!uatContent) return null;
 
-  // If UAT result already exists, skip (idempotent)
+  // If UAT result already exists with a PASS verdict, skip (idempotent).
+  // Non-PASS verdicts (FAIL, surfaced-for-human-review) should block slice
+  // progression — return the slice for re-evaluation (#1231).
   const uatResultFile = resolveSliceFile(base, mid, sid, "UAT-RESULT");
   if (uatResultFile) {
-    const hasResult = !!(await loadFile(uatResultFile));
-    if (hasResult) return null;
+    const resultContent = await loadFile(uatResultFile);
+    if (resultContent) {
+      const verdictMatch = resultContent.match(/verdict:\s*([\w-]+)/i);
+      const verdict = verdictMatch?.[1]?.toLowerCase();
+      if (verdict === "pass" || verdict === "passed") return null; // PASS — skip
+      // Non-PASS verdict exists — don't re-run UAT, but don't advance either.
+      // Return null here since the UAT already ran; the dispatch table's
+      // complete-slice rule should check the verdict before advancing.
+      // For now, returning the slice signals it still needs attention.
+    }
   }
 
   // Classify UAT type; unknown type → treat as human-experience (human review)