diff --git a/.changeset/3541-installer-migration-prompt-user-resolution.md b/.changeset/3541-installer-migration-prompt-user-resolution.md
index e329b3f37..fbb79c128 100644
--- a/.changeset/3541-installer-migration-prompt-user-resolution.md
+++ b/.changeset/3541-installer-migration-prompt-user-resolution.md
@@ -3,4 +3,4 @@ type: Fixed
 pr: 3547
 ---
 
-**Installer migration no longer hangs `/gsd-update` on leftover GSD-looking files** — non-TTY installer runs now default-resolve `prompt-user` migration actions by classification (stale SDK build artifacts under `get-shit-done/sdk/{dist,src}/gsd-*` default to `remove`; user-facing `skills/gsd-*/SKILL.md` defaults to `keep`) and log each resolution. Anything that cannot be safely defaulted still blocks, but the error message now groups blocked paths by reason, lists the documented choices, and names the `GSD_INSTALLER_MIGRATION_RESOLVE` env var as the non-interactive resolution surface. (#0)
+**Installer migration no longer hangs `/gsd:update` on leftover GSD-looking files** — non-TTY installer runs now default-resolve `prompt-user` migration actions by classification (stale SDK build artifacts under `get-shit-done/sdk/{dist,src}/gsd-*` default to `remove`; user-facing `skills/gsd-*/SKILL.md` defaults to `keep`) and log each resolution. Anything that cannot be safely defaulted still blocks, but the error message now groups blocked paths by reason, lists the documented choices, and names the `GSD_INSTALLER_MIGRATION_RESOLVE` env var as the non-interactive resolution surface. (#3541)
diff --git a/get-shit-done/bin/lib/installer-migration-report.cjs b/get-shit-done/bin/lib/installer-migration-report.cjs
index f8b772957..700c4645e 100644
--- a/get-shit-done/bin/lib/installer-migration-report.cjs
+++ b/get-shit-done/bin/lib/installer-migration-report.cjs
@@ -140,6 +140,20 @@ function materializeResolution(action, choice) {
   return { ...base, type: 'backup-and-remove', backupRelPath: null };
 }
 
+function normalizeResolutionChoice(rawValue) {
+  if (typeof rawValue !== 'string') return null;
+  const normalized = rawValue.trim().toLowerCase();
+  return VALID_CHOICES.includes(normalized) ? normalized : null;
+}
+
+function actionSupportsChoice(action, choice) {
+  if (!action || !choice) return false;
+  if (!Array.isArray(action.choices) || action.choices.length === 0) {
+    return VALID_CHOICES.includes(choice);
+  }
+  return action.choices.includes(choice);
+}
+
 // Resolve prompt-user actions when stdin is not a TTY. Mutates the
 // passed result so:
 //   - resolved actions are appended to plan.actions in their concrete
@@ -164,14 +178,34 @@ function resolveInstallerMigrationPromptsForNonTty(result, options = {}) {
     return { result, resolutions: [] };
   }
 
+  const env =
+    options && options.env && typeof options.env === 'object'
+      ? options.env
+      : process.env;
+  const envChoice = normalizeResolutionChoice(env && env[RESOLUTION_ENV_VAR]);
   const resolutions = [];
   const unresolved = [];
 
   for (const action of blocked) {
     if (action && action.type === 'prompt-user') {
-      const classification = classifyPromptUserAction(action);
-      if (classification) {
-        const resolved = materializeResolution(action, classification.choice);
+      let category = null;
+      let choice = null;
+      let source = null;
+      if (envChoice && actionSupportsChoice(action, envChoice)) {
+        category = 'operator-override';
+        choice = envChoice;
+        source = RESOLUTION_ENV_VAR;
+      } else {
+        const classification = classifyPromptUserAction(action);
+        if (classification) {
+          category = classification.category;
+          choice = classification.choice;
+          source = 'non-tty-default';
+        }
+      }
+
+      if (choice) {
+        const resolved = materializeResolution(action, choice);
         // Inject the concrete action into plan.actions so the apply
         // step picks it up.
         if (result.plan && Array.isArray(result.plan.actions)) {
@@ -179,11 +213,11 @@ function resolveInstallerMigrationPromptsForNonTty(result, options = {}) {
         }
         resolutions.push({
           relPath: action.relPath,
-          category: classification.category,
-          choice: classification.choice,
+          category,
+          choice,
           reason: action.reason,
           resolvedActionType: resolved.type,
-          source: 'non-tty-default',
+          source,
         });
         continue;
       }
diff --git a/tests/bug-3541-installer-migration-prompt-user-resolution.test.cjs b/tests/bug-3541-installer-migration-prompt-user-resolution.test.cjs
index 4a44a42ba..54923ac03 100644
--- a/tests/bug-3541-installer-migration-prompt-user-resolution.test.cjs
+++ b/tests/bug-3541-installer-migration-prompt-user-resolution.test.cjs
@@ -198,4 +198,42 @@ describe('#3541: installer migration prompt-user non-TTY resolution', { concurre
     assert.equal(reasons.length, 1, 'two same-reason paths grouped under one key');
     assert.equal(captured.blockedByReason[reasons[0]].length, 2);
   });
+
+  test('Test C: non-TTY env override resolves otherwise-unclassified prompt-user actions', () => {
+    const result = {
+      blocked: [
+        {
+          type: 'prompt-user',
+          relPath: 'skills/gsd-custom/SKILL.toml',
+          reason: 'custom skill metadata requires user decision',
+          choices: ['keep', 'remove'],
+        },
+      ],
+      plan: {
+        actions: [],
+        blocked: [
+          {
+            type: 'prompt-user',
+            relPath: 'skills/gsd-custom/SKILL.toml',
+            reason: 'custom skill metadata requires user decision',
+            choices: ['keep', 'remove'],
+          },
+        ],
+      },
+    };
+
+    const resolved = resolveInstallerMigrationPromptsForNonTty(result, {
+      isTty: false,
+      env: { GSD_INSTALLER_MIGRATION_RESOLVE: 'keep' },
+    });
+
+    assert.equal(resolved.resolutions.length, 1, 'env override resolves prompt-user action');
+    assert.equal(resolved.resolutions[0].choice, 'keep');
+    assert.equal(resolved.resolutions[0].source, 'GSD_INSTALLER_MIGRATION_RESOLVE');
+    assert.equal(resolved.resolutions[0].category, 'operator-override');
+    assert.equal((resolved.result.blocked || []).length, 0);
+    assert.equal((resolved.result.plan.blocked || []).length, 0);
+    assert.equal((resolved.result.plan.actions || []).length, 1);
+    assert.equal(resolved.result.plan.actions[0].type, 'baseline-preserve-user');
+  });
 });