diff --git a/gsd-core/workflows/onboard.md b/gsd-core/workflows/onboard.md
index 7166317f5..5d6d83187 100644
--- a/gsd-core/workflows/onboard.md
+++ b/gsd-core/workflows/onboard.md
@@ -74,6 +74,21 @@ Then rerun /gsd:onboard from the same worktree root.
 
 Exit. If the user skips mapping:
 
+- If `planning_exists && (!project_exists || !requirements_exists || !roadmap_exists || !state_exists)`, route the skip to the partial planning guard instead:
+
+```text
+Skipping codebase mapping may give downstream steps weaker context, but project planning exists and is incomplete.
+
+PROJECT.md: {project_exists ? "present" : "missing"}
+REQUIREMENTS.md: {requirements_exists ? "present" : "missing"}
+ROADMAP.md: {roadmap_exists ? "present" : "missing"}
+STATE.md: {state_exists ? "present" : "missing"}
+
+Run the appropriate lower-level command to fill the missing planning artifact(s), then rerun /gsd:onboard.
+```
+
+Exit.
+
 - If `has_docs_candidates && !project_exists`, route the skip to docs ingest instead:
 
 ```text
diff --git a/tests/onboard-command.test.cjs b/tests/onboard-command.test.cjs
index 4904e18c2..b3ab7a64b 100644
--- a/tests/onboard-command.test.cjs
+++ b/tests/onboard-command.test.cjs
@@ -375,10 +375,22 @@ describe('/gsd:onboard command contract', () => {
       content.includes('Exit. If the user skips mapping:'),
       'skip mapping must hand off explicitly instead of falling through to summary creation',
     );
+    const partialPlanningSkipGuard =
+      'If `planning_exists && (!project_exists || !requirements_exists || !roadmap_exists || !state_exists)`, route the skip to the partial planning guard instead:';
+    const docsIngestSkipGuard =
+      'If `has_docs_candidates && !project_exists`, route the skip to docs ingest instead:';
     assert.ok(
-      content.includes('If `has_docs_candidates && !project_exists`, route the skip to docs ingest instead:'),
+      content.includes(partialPlanningSkipGuard),
+      'skip mapping must preserve the partial-planning guard when incomplete planning artifacts are present',
+    );
+    assert.ok(
+      content.includes(docsIngestSkipGuard),
       'skip mapping must preserve the docs-ingest gate when planning docs are present',
     );
+    assert.ok(
+      content.indexOf(partialPlanningSkipGuard) < content.indexOf(docsIngestSkipGuard),
+      'skip mapping must check partial planning before docs ingest',
+    );
     assert.ok(
       content.includes('/gsd:ingest-docs'),
       'skip mapping docs-preserving handoff must name the docs ingest command',