diff --git a/.github/workflows/pr-review-merge-scheduler.yml b/.github/workflows/pr-review-merge-scheduler.yml
index 8319ae5be..1cf376ad9 100644
--- a/.github/workflows/pr-review-merge-scheduler.yml
+++ b/.github/workflows/pr-review-merge-scheduler.yml
@@ -244,6 +244,7 @@ jobs:
             {
               printf 'repository=%s\n' "$GITHUB_REPOSITORY"
               printf 'base_branch=%s\n' "$DEFAULT_BRANCH"
+              printf 'repository_default_branch=%s\n' "$DEFAULT_BRANCH"
             } >>"$GITHUB_OUTPUT"
             exit 0
           fi
@@ -281,13 +282,15 @@ jobs:
           live_head_repository="$(jq -r '.head.repo.full_name // empty' <<<"$pull_json")"
           live_base_branch="$(jq -r '.base.ref // empty' <<<"$pull_json")"
           live_head_sha="$(jq -r '.head.sha // empty' <<<"$pull_json")"
+          repository_default_branch="$(gh api "repos/${TARGET_REPOSITORY_INPUT}" --jq '.default_branch // empty')"
           if [ "$live_number" != "$TARGET_PR_NUMBER" ] ||
             [ "$live_state" != "open" ] ||
             [ "$live_base_repository" != "$TARGET_REPOSITORY_INPUT" ] ||
             [ "$live_head_repository" != "$TARGET_REPOSITORY_INPUT" ] ||
             [ -z "$live_base_branch" ] ||
+            [ -z "$repository_default_branch" ] ||
             ! [[ "$live_head_sha" =~ ^[0-9a-fA-F]{40}$ ]]; then
-            printf '::error::Targeted scheduler dispatch rejected closed, cross-repository, or malformed live PR metadata. target=%s pr=%s state=%s base_repository=%s head_repository=%s base_branch=%s head_sha=%s\n' "$TARGET_REPOSITORY_INPUT" "$TARGET_PR_NUMBER" "${live_state:-<missing>}" "${live_base_repository:-<missing>}" "${live_head_repository:-<missing>}" "${live_base_branch:-<missing>}" "${live_head_sha:-<missing>}"
+            printf '::error::Targeted scheduler dispatch rejected closed, cross-repository, or malformed live PR metadata. target=%s pr=%s state=%s base_repository=%s head_repository=%s base_branch=%s repository_default_branch=%s head_sha=%s\n' "$TARGET_REPOSITORY_INPUT" "$TARGET_PR_NUMBER" "${live_state:-<missing>}" "${live_base_repository:-<missing>}" "${live_head_repository:-<missing>}" "${live_base_branch:-<missing>}" "${repository_default_branch:-<missing>}" "${live_head_sha:-<missing>}"
             exit 1
           fi
           if [ -n "$TARGET_BASE_BRANCH_INPUT" ] &&
@@ -299,9 +302,10 @@ jobs:
           {
             printf 'repository=%s\n' "$TARGET_REPOSITORY_INPUT"
             printf 'base_branch=%s\n' "$live_base_branch"
+            printf 'repository_default_branch=%s\n' "$repository_default_branch"
             printf 'head_sha=%s\n' "$live_head_sha"
           } >>"$GITHUB_OUTPUT"
-          printf 'Validated exact targeted scheduler dispatch for %s#%s at %s on base %s.\n' "$TARGET_REPOSITORY_INPUT" "$TARGET_PR_NUMBER" "$live_head_sha" "$live_base_branch"
+          printf 'Validated exact targeted scheduler dispatch for %s#%s at %s on base %s; repository default branch is %s.\n' "$TARGET_REPOSITORY_INPUT" "$TARGET_PR_NUMBER" "$live_head_sha" "$live_base_branch" "$repository_default_branch"
 
       - name: Resolve trusted scheduler source ref
         id: trusted_source
@@ -482,7 +486,7 @@ jobs:
         env:
           GH_TOKEN: ${{ secrets.PR_REVIEW_MERGE_TOKEN || secrets.OPENCODE_APPROVE_TOKEN || steps.scheduler_app_token.outputs.token || github.token }}
           TARGET_REPOSITORY: ${{ steps.targeted_dispatch.outputs.repository }}
-          TARGET_DEFAULT_BRANCH: ${{ steps.targeted_dispatch.outputs.base_branch }}
+          TARGET_DEFAULT_BRANCH: ${{ steps.targeted_dispatch.outputs.repository_default_branch }}
           SCHEDULER_ACTIONS_TOKEN: ${{ github.event_name == 'repository_dispatch' && github.event.client_payload.target_repository != '' && (secrets.PR_REVIEW_MERGE_TOKEN || secrets.OPENCODE_APPROVE_TOKEN || steps.scheduler_app_token.outputs.token) || github.token }}
           # Same-repository dispatch credential: when this scheduler runs inside
           # ContextualWisdomLab/.github (the repository the required workflows are
diff --git a/tests/test_opencode_workflow_shell_syntax.py b/tests/test_opencode_workflow_shell_syntax.py
index ec6edca40..cd6f620a5 100644
--- a/tests/test_opencode_workflow_shell_syntax.py
+++ b/tests/test_opencode_workflow_shell_syntax.py
@@ -170,8 +170,17 @@ def test_merge_scheduler_targeted_dispatch_validates_live_exact_pr(tmp_path):
         """#!/usr/bin/env bash
 set -euo pipefail
 test "$1" = api
-test "$2" = repos/ContextualWisdomLab/naruon/pulls/1179
-printf '%s\\n' "$FAKE_PULL_JSON"
+case "$2" in
+  repos/ContextualWisdomLab/naruon/pulls/1179)
+    printf '%s\\n' "$FAKE_PULL_JSON"
+    ;;
+  repos/ContextualWisdomLab/naruon)
+    printf '%s\\n' 'develop'
+    ;;
+  *)
+    exit 1
+    ;;
+esac
 """,
         encoding="utf-8",
     )
@@ -180,7 +189,7 @@ def test_merge_scheduler_targeted_dispatch_validates_live_exact_pr(tmp_path):
         "number": 1179,
         "state": "open",
         "base": {
-            "ref": "develop",
+            "ref": "feat/stack",
             "repo": {"full_name": "ContextualWisdomLab/naruon"},
         },
         "head": {
@@ -199,7 +208,7 @@ def test_merge_scheduler_targeted_dispatch_validates_live_exact_pr(tmp_path):
         "DEFAULT_BRANCH": "main",
         "TARGET_REPOSITORY_INPUT": "ContextualWisdomLab/naruon",
         "TARGET_PR_NUMBER": "1179",
-        "TARGET_BASE_BRANCH_INPUT": "develop",
+        "TARGET_BASE_BRANCH_INPUT": "feat/stack",
         "ALLOWED_TARGET_REPOSITORIES": (
             "ContextualWisdomLab/.github, ContextualWisdomLab/naruon"
         ),
@@ -217,7 +226,8 @@ def test_merge_scheduler_targeted_dispatch_validates_live_exact_pr(tmp_path):
     assert accepted.returncode == 0, accepted.stderr
     assert output.read_text(encoding="utf-8").splitlines() == [
         "repository=ContextualWisdomLab/naruon",
-        "base_branch=develop",
+        "base_branch=feat/stack",
+        "repository_default_branch=develop",
         "head_sha=4afd4af7ad343660356791873d940aa2846f40c2",
     ]
 
diff --git a/tests/test_required_workflow_queue_contract.py b/tests/test_required_workflow_queue_contract.py
index 535fd513a..127b8c0dc 100644
--- a/tests/test_required_workflow_queue_contract.py
+++ b/tests/test_required_workflow_queue_contract.py
@@ -66,6 +66,8 @@ def test_targeted_scheduler_dispatch_is_allowlisted_and_exact_pr_scoped() -> Non
     assert "TARGET_REPOSITORY_INPUT:" in validation
     assert "TARGET_PR_NUMBER:" in validation
     assert "TARGET_BASE_BRANCH_INPUT:" in validation
+    assert "repository_default_branch=\"$(gh api \"repos/${TARGET_REPOSITORY_INPUT}\" --jq '.default_branch // empty')\"" in validation
+    assert "repository_default_branch=%s\\n" in validation
     assert (
         "ALLOWED_TARGET_REPOSITORIES: ${{ "
         "vars.OPENCODE_REPOSITORY_DISPATCH_TARGETS }}"
@@ -79,7 +81,7 @@ def test_targeted_scheduler_dispatch_is_allowlisted_and_exact_pr_scoped() -> Non
     assert "Targeted scheduler dispatch base branch does not match the live PR" in validation
     assert "TARGET_REPOSITORY: ${{ steps.targeted_dispatch.outputs.repository }}" in inspect
     assert (
-        "TARGET_DEFAULT_BRANCH: ${{ steps.targeted_dispatch.outputs.base_branch }}"
+        "TARGET_DEFAULT_BRANCH: ${{ steps.targeted_dispatch.outputs.repository_default_branch }}"
         in inspect
     )
     assert '--repo "$TARGET_REPOSITORY"' in inspect