diff --git a/apps/memos-local-plugin/core/skill/crystallize.ts b/apps/memos-local-plugin/core/skill/crystallize.ts
index c45c5453d..17e9ad146 100644
--- a/apps/memos-local-plugin/core/skill/crystallize.ts
+++ b/apps/memos-local-plugin/core/skill/crystallize.ts
@@ -470,11 +470,34 @@ function capString(s: string, cap: number): string {
 
 /**
  * A sensible default validator used both in production and in tests.
- * Throws if the draft is structurally unusable (no name, no steps, no summary).
+ * Throws only when the draft is structurally unusable (no name). Missing
+ * summary/steps are repaired from the remaining fields instead — LLMs (e.g.
+ * deepseek-v4-flash) routinely return valid JSON drafts that omit `summary`
+ * or the `steps` array, and rejecting those stalls the crystallizer queue
+ * (see issue #2143).
  */
 export function defaultDraftValidator(draft: SkillCrystallizationDraft): void {
   if (!draft.name) throw new Error("skill.crystallize.invalid: missing name");
-  if (!draft.summary) throw new Error("skill.crystallize.invalid: missing summary");
-  if (draft.steps.length === 0)
-    throw new Error("skill.crystallize.invalid: missing steps");
+  if (!draft.summary) {
+    // Auto-generate a summary from the richest available field. Use `||` not
+    // `??`: LLM JSON emits empty strings, and `??` only falls through on
+    // null/undefined.
+    const autoSummary =
+      draft.steps?.[0]?.body ||
+      draft.steps?.[0]?.title ||
+      draft.displayTitle ||
+      draft.name ||
+      "skill procedure";
+    draft.summary = autoSummary.slice(0, 200);
+  }
+  if (!draft.steps || draft.steps.length === 0) {
+    // Auto-generate a single step when the LLM omits the steps array
+    // (mirror of the summary fallback chain above).
+    const autoBody = draft.summary || draft.displayTitle || draft.name || "";
+    if (autoBody) {
+      draft.steps = [{ title: "Execute the fix", body: autoBody.slice(0, 2000) }];
+    } else {
+      throw new Error("skill.crystallize.invalid: missing steps");
+    }
+  }
 }
diff --git a/apps/memos-local-plugin/tests/unit/skill/crystallize-validator.test.ts b/apps/memos-local-plugin/tests/unit/skill/crystallize-validator.test.ts
new file mode 100644
index 000000000..348a2ac72
--- /dev/null
+++ b/apps/memos-local-plugin/tests/unit/skill/crystallize-validator.test.ts
@@ -0,0 +1,62 @@
+import { describe, expect, it } from "vitest";
+
+import { defaultDraftValidator } from "../../../core/skill/crystallize.js";
+import { makeDraft } from "./_helpers.js";
+
+describe("defaultDraftValidator", () => {
+  it("passes a complete draft through unchanged", () => {
+    const draft = makeDraft();
+    expect(() => defaultDraftValidator(draft)).not.toThrow();
+    expect(draft.summary).toBe("Ensure system libs exist before pip install on alpine.");
+    expect(draft.steps).toHaveLength(3);
+  });
+
+  it("never throws for a missing summary (issue #2143)", () => {
+    const draft = makeDraft({ summary: "" });
+    expect(() => defaultDraftValidator(draft)).not.toThrow();
+  });
+
+  it("auto-generates summary from the first step body when omitted", () => {
+    const draft = makeDraft({ summary: "" });
+    defaultDraftValidator(draft);
+    expect(draft.summary).toBe("inspect the pip error for missing .so names");
+  });
+
+  it("falls back through step title, displayTitle, then name for the summary", () => {
+    const draft = makeDraft({ summary: "", steps: [] });
+    defaultDraftValidator(draft);
+    expect(draft.summary).toBe("Alpine pip install with system deps");
+  });
+
+  it("caps the auto-generated summary at 200 chars", () => {
+    const longBody = "x".repeat(500);
+    const draft = makeDraft({
+      summary: "",
+      steps: [{ title: "t", body: longBody }],
+    });
+    defaultDraftValidator(draft);
+    expect(draft.summary).toBe("x".repeat(200));
+  });
+
+  it("uses || not ?? — an empty-string summary still triggers the fallback", () => {
+    const draft = makeDraft({ summary: "", steps: [] });
+    defaultDraftValidator(draft);
+    expect(draft.summary).not.toBe("");
+  });
+
+  it("auto-generates a single step when the steps array is empty", () => {
+    const draft = makeDraft({ steps: [] });
+    defaultDraftValidator(draft);
+    expect(draft.steps).toEqual([
+      {
+        title: "Execute the fix",
+        body: "Ensure system libs exist before pip install on alpine.",
+      },
+    ]);
+  });
+
+  it("still rejects a draft with no name", () => {
+    const draft = makeDraft({ name: "" });
+    expect(() => defaultDraftValidator(draft)).toThrow(/missing name/);
+  });
+});
diff --git a/apps/memos-local-plugin/tests/unit/skill/crystallize.test.ts b/apps/memos-local-plugin/tests/unit/skill/crystallize.test.ts
index a2e0e63eb..bcaccaf67 100644
--- a/apps/memos-local-plugin/tests/unit/skill/crystallize.test.ts
+++ b/apps/memos-local-plugin/tests/unit/skill/crystallize.test.ts
@@ -230,7 +230,10 @@ describe("skill/crystallize", () => {
     expect(r.modelRefusal?.content).toContain("I cannot process this request");
   });
 
-  it("rejects drafts that the validator flags as invalid", async () => {
+  it("repairs drafts the strict validator would have rejected (issue #2143)", async () => {
+    // A draft with an empty summary AND no steps used to be rejected with
+    // skill.crystallize.invalid: missing summary / missing steps. The lenient
+    // validator auto-generates both, so the same draft now crystallizes.
     const llm = fakeLlm({
       completeJson: {
         "skill.crystallize": makeDraft({ steps: [], summary: "" }) as unknown,
@@ -240,6 +243,10 @@ describe("skill/crystallize", () => {
       { policy: mkPolicy(), evidence: [mkTrace("tr_1", "x")], namingSpace: [] },
       { llm, log, config: makeSkillConfig(), validate: defaultDraftValidator },
     );
-    expect(r.ok).toBe(false);
+    expect(r.ok).toBe(true);
+    if (r.ok) {
+      expect(r.draft.summary).not.toBe("");
+      expect(r.draft.steps.length).toBeGreaterThan(0);
+    }
   });
 });