diff --git a/.changeset/fn-7181-pr-generation-prompt-and-loading.md b/.changeset/fn-7181-pr-generation-prompt-and-loading.md
new file mode 100644
index 0000000000..2756660e73
--- /dev/null
+++ b/.changeset/fn-7181-pr-generation-prompt-and-loading.md
@@ -0,0 +1,7 @@
+---
+"@runfusion/fusion": minor
+---
+
+summary: Improve AI-generated PR titles and descriptions, and show a clear loading state while the description generates.
+category: feature
+dev: Rewrote the pr-metadata-generator system/context prompt (exported as a named default constant) for grounded, conventional-commit-style output while preserving the strict {title,summary,changes,testing,linkedTask} JSON schema; PrCreateModal now renders a skeleton + aria-busy loading affordance with disabled inputs during generation that clears into content or the existing error/manual-fallback path.
diff --git a/docs/dashboard-guide.md b/docs/dashboard-guide.md
index ac1e5b3117..11fa16dde0 100644
--- a/docs/dashboard-guide.md
+++ b/docs/dashboard-guide.md
@@ -1004,7 +1004,7 @@ Inspect task definition, logs, review feedback, comments, artifacts, workflow ou
 - The **Create Pull Request** modal is a floating pop-out like Plan Mission, New Task, and Automations: drag its header or resize from desktop edges/corners, while mobile keeps the full-screen dialog layout. Close it with **X**, **Cancel**, or **Escape**; stray clicks inside or outside the floating shell do not dismiss it.
 - The modal shell renders immediately: preflight checks and PR options load independently of AI-generated title/body metadata, so slow AI suggestions no longer block base-branch selection, diagnostics, or manual PR authoring. The **Diff & commit preview** section starts collapsed and can be expanded on demand.
 - The **Body** section includes a **Preview/Edit** toggle so authors can review the rendered markdown description before creating the PR without changing the submitted raw body text.
-- AI title/body generation in the dialog is bounded to 15 seconds and is canceled if the request disconnects; on timeout/cancel, Fusion falls back to deterministic task-based PR title/body content instead of leaving the spinner stuck forever.
+- AI title/body generation is bounded to 60 seconds on the server and 15 seconds in the dialog, and is canceled if the request disconnects; while it runs, the title and body fields show a skeleton loading state and are temporarily disabled, then resolve into generated content or deterministic task-based fallback content on timeout/cancel.
 - Project Settings → Project Models includes optional **PR title prompt guidance** and **PR description prompt guidance** fields. Blank fields preserve the default Create PR metadata prompt; populated fields append guidance for the generated title or body sections.
 - The **Artifacts** tab combines task documents written by agents or users with task-scoped registered media artifacts. The gallery uses thumbnail-first image/video cards, image and video previews can expand into a dismissible full-size lightbox, video and audio use native controls, document artifacts show text previews, and generic artifacts open through their media URL.
 - The **Review** tab is separate from **Comments**: Review shows actionable PR/reviewer feedback and same-task revision controls, while Comments remains the general collaboration thread.
diff --git a/packages/dashboard/app/components/PrCreateModal.css b/packages/dashboard/app/components/PrCreateModal.css
index 4531afbd41..9de1571af1 100644
--- a/packages/dashboard/app/components/PrCreateModal.css
+++ b/packages/dashboard/app/components/PrCreateModal.css
@@ -179,6 +179,68 @@ FN-7170 hosts Create PR in FloatingWindow: desktop geometry belongs to the share
   margin-bottom: 0;
 }
 
+.pr-create-modal__field-shell {
+  position: relative;
+}
+
+.pr-create-modal__field-shell > .input:disabled {
+  cursor: wait;
+}
+
+.pr-create-modal__metadata-skeleton {
+  position: absolute;
+  inset: var(--btn-border-width);
+  pointer-events: none;
+  border-radius: var(--radius-md);
+  background: color-mix(in srgb, var(--border) 70%, var(--surface));
+  animation: pr-create-modal-skeleton-pulse 1.4s ease-in-out infinite;
+}
+
+.pr-create-modal__metadata-skeleton--title {
+  inline-size: min(100%, calc(var(--space-2xl) * 7));
+}
+
+.pr-create-modal__metadata-skeleton--body {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-sm);
+  padding: var(--space-md);
+  background: color-mix(in srgb, var(--surface) 82%, var(--border));
+}
+
+.pr-create-modal__metadata-skeleton--body span {
+  display: block;
+  block-size: var(--space-md);
+  border-radius: var(--radius-sm);
+  background: color-mix(in srgb, var(--border) 72%, var(--surface));
+}
+
+.pr-create-modal__metadata-skeleton--body span:nth-child(1) {
+  inline-size: 92%;
+}
+
+.pr-create-modal__metadata-skeleton--body span:nth-child(2) {
+  inline-size: 78%;
+}
+
+.pr-create-modal__metadata-skeleton--body span:nth-child(3) {
+  inline-size: 88%;
+}
+
+.pr-create-modal__metadata-skeleton--body span:nth-child(4) {
+  inline-size: 64%;
+}
+
+@keyframes pr-create-modal-skeleton-pulse {
+  0%, 100% {
+    opacity: 0.58;
+  }
+
+  50% {
+    opacity: 1;
+  }
+}
+
 .pr-create-template-hint {
   margin: 0;
   color: var(--text-muted);
diff --git a/packages/dashboard/app/components/PrCreateModal.tsx b/packages/dashboard/app/components/PrCreateModal.tsx
index 57642ebfb8..8102557fc4 100644
--- a/packages/dashboard/app/components/PrCreateModal.tsx
+++ b/packages/dashboard/app/components/PrCreateModal.tsx
@@ -640,7 +640,11 @@ export function PrCreateModal({
               ) : null}
             </section>
 
-            <section className="pr-create-modal__section">
+            {/**
+             * FNXC:PrCreateModal 2026-06-28-00:09:
+             * PR title/body generation must read as active description work, not as empty editable fields. Keep both fields disabled with aria-busy plus a skeleton while metadataLoading is true, then clear the affordance into AI content or the existing metadataError/manual-fallback state.
+             */}
+            <section className="pr-create-modal__section" aria-busy={metadataLoading ? "true" : undefined}>
               <div className="pr-create-modal__title-row">
                 <label className="pr-create-modal__label" htmlFor="pr-create-modal-title">{t("pr.titleLabel", "Title")}</label>
                 <div className="pr-create-modal__inline-actions">
@@ -650,10 +654,20 @@ export function PrCreateModal({
               </div>
               {metadataLoading ? <div className="pr-create-modal__loading pr-create-modal__section-loading"><span className="status-dot status-dot--pending" aria-hidden="true" />{t("pr.generatingTitle", "Generating AI title…")}</div> : null}
               {metadataError ? <div className="form-error pr-error" role="alert"><p>{metadataError}</p></div> : null}
-              <input id="pr-create-modal-title" className="input" value={title} onChange={(event) => { setTitle(event.target.value); setUserEditedTitle(true); }} />
+              <div className="pr-create-modal__field-shell">
+                <input
+                  id="pr-create-modal-title"
+                  className="input"
+                  value={title}
+                  onChange={(event) => { setTitle(event.target.value); setUserEditedTitle(true); }}
+                  disabled={metadataLoading}
+                  aria-busy={metadataLoading ? "true" : undefined}
+                />
+                {metadataLoading ? <div className="pr-create-modal__metadata-skeleton pr-create-modal__metadata-skeleton--title" data-testid="pr-title-loading-skeleton" aria-hidden="true" /> : null}
+              </div>
             </section>
 
-            <section className="pr-create-modal__section">
+            <section className="pr-create-modal__section" aria-busy={metadataLoading ? "true" : undefined}>
               <div className="pr-create-modal__title-row">
                 <label className="pr-create-modal__label" htmlFor="pr-create-modal-body">{t("pr.bodyLabel", "Body")}</label>
                 <div className="pr-create-modal__inline-actions">
@@ -675,13 +689,34 @@ export function PrCreateModal({
               {/**
                * FNXC:PrCreateModal 2026-06-28-00:00:
                * PR authors need to preview description markdown before creating the PR. The preview is render-only, uses the shared sanitized markdown pipeline, and submission/regeneration/revert always read and write the raw `body` state.
+               *
+               * FNXC:PrCreateModal 2026-06-28-00:16:
+               * While AI metadata is generating, disable raw editing and show skeleton affordances even when Preview is selected so users see that the submitted body is still pending generation.
                */}
-              {showBodyPreview ? (
+              {showBodyPreview && !metadataLoading ? (
                 <div className="pr-create-modal__body-preview markdown-body" role="region" aria-label={t("pr.bodyPreviewLabel", "Body markdown preview")}>
                   <ReactMarkdown remarkPlugins={[remarkGfm]} rehypePlugins={sharedRehypePlugins}>{body}</ReactMarkdown>
                 </div>
               ) : (
-                <textarea id="pr-create-modal-body" className="input pr-create-modal__body-input" value={body} onChange={(event) => { setBody(event.target.value); setUserEditedBody(true); }} rows={8} />
+                <div className="pr-create-modal__field-shell">
+                  <textarea
+                    id="pr-create-modal-body"
+                    className="input pr-create-modal__body-input"
+                    value={body}
+                    onChange={(event) => { setBody(event.target.value); setUserEditedBody(true); }}
+                    rows={8}
+                    disabled={metadataLoading}
+                    aria-busy={metadataLoading ? "true" : undefined}
+                  />
+                  {metadataLoading ? (
+                    <div className="pr-create-modal__metadata-skeleton pr-create-modal__metadata-skeleton--body" data-testid="pr-body-loading-skeleton" aria-hidden="true">
+                      <span />
+                      <span />
+                      <span />
+                      <span />
+                    </div>
+                  ) : null}
+                </div>
               )}
               {templateUsed && <p className="pr-create-template-hint">{t("pr.usingTemplate", "Using <code>.github/pull_request_template.md</code>")}</p>}
             </section>
@@ -790,7 +825,7 @@ export function PrCreateModal({
 
         <div className="modal-actions">
           <button type="button" className="btn" onClick={onClose} disabled={submitting}>{t("actions.cancel", "Cancel")}</button>
-          <button type="button" className="btn btn-primary" onClick={() => void submit()} disabled={!preflight || preflightLoading || !canSubmit || !hasRequiredPrContent || submitting}>
+          <button type="button" className="btn btn-primary" onClick={() => void submit()} disabled={!preflight || preflightLoading || metadataLoading || !canSubmit || !hasRequiredPrContent || submitting}>
             {submitting ? <RefreshCw size={14} className="spin" /> : null}
             {draft ? t("pr.createDraftPr", "Create draft PR") : t("pr.createPr", "Create PR")}
           </button>
diff --git a/packages/dashboard/app/components/__tests__/PrCreateModal.test.tsx b/packages/dashboard/app/components/__tests__/PrCreateModal.test.tsx
index fd990311ce..9d12a72875 100644
--- a/packages/dashboard/app/components/__tests__/PrCreateModal.test.tsx
+++ b/packages/dashboard/app/components/__tests__/PrCreateModal.test.tsx
@@ -87,6 +87,32 @@ function stubPointerCapture(element: HTMLElement) {
   Object.defineProperty(element, "releasePointerCapture", { configurable: true, value: vi.fn() });
 }
 
+function expectMetadataLoadingAffordance() {
+  const titleInput = screen.getByLabelText(/title/i);
+  const bodyInput = screen.getByLabelText(/body/i);
+  expect(screen.getByText(/generating ai title/i)).toBeInTheDocument();
+  expect(screen.getByText(/generating ai body/i)).toBeInTheDocument();
+  expect(screen.getByTestId("pr-title-loading-skeleton")).toBeInTheDocument();
+  expect(screen.getByTestId("pr-body-loading-skeleton")).toBeInTheDocument();
+  expect(titleInput).toBeDisabled();
+  expect(bodyInput).toBeDisabled();
+  expect(titleInput).toHaveAttribute("aria-busy", "true");
+  expect(bodyInput).toHaveAttribute("aria-busy", "true");
+}
+
+function expectMetadataLoadingCleared() {
+  const titleInput = screen.getByLabelText(/title/i);
+  const bodyInput = screen.getByLabelText(/body/i);
+  expect(screen.queryByText(/generating ai title/i)).not.toBeInTheDocument();
+  expect(screen.queryByText(/generating ai body/i)).not.toBeInTheDocument();
+  expect(screen.queryByTestId("pr-title-loading-skeleton")).not.toBeInTheDocument();
+  expect(screen.queryByTestId("pr-body-loading-skeleton")).not.toBeInTheDocument();
+  expect(titleInput).toBeEnabled();
+  expect(bodyInput).toBeEnabled();
+  expect(titleInput).not.toHaveAttribute("aria-busy");
+  expect(bodyInput).not.toHaveAttribute("aria-busy");
+}
+
 describe("PrCreateModal", () => {
   beforeEach(() => {
     localStorage.clear();
@@ -408,7 +434,7 @@ describe("PrCreateModal", () => {
     expect(document.querySelectorAll(".pr-create-modal__commit-row")).toHaveLength(0);
   });
 
-  it("renders preflight and options before metadata resolves", async () => {
+  it("renders preflight and options while metadata shows a disabled loading affordance, then clears into AI content", async () => {
     const metadataDeferred = createDeferred<typeof metadata>();
     mocks.generatePrMetadata.mockReturnValueOnce(metadataDeferred.promise);
 
@@ -417,20 +443,19 @@ describe("PrCreateModal", () => {
     expect(await screen.findByText("Branch pushed to remote")).toBeInTheDocument();
     expect(screen.getByLabelText(/base branch/i)).toBeEnabled();
     expect(screen.getByText("Reviewers")).toBeInTheDocument();
-    expect(screen.getByText(/generating ai title/i)).toBeInTheDocument();
+    expectMetadataLoadingAffordance();
     expect(screen.getByRole("button", { name: "Create PR" })).toBeDisabled();
 
-    fireEvent.change(screen.getByLabelText(/title/i), { target: { value: "Manual PR title" } });
-    expect(screen.getByRole("button", { name: "Create PR" })).toBeDisabled();
-    fireEvent.change(screen.getByLabelText(/body/i), { target: { value: "Manual PR body" } });
-    await waitFor(() => expect(screen.getByRole("button", { name: "Create PR" })).toBeEnabled());
-
     fireEvent.change(screen.getByPlaceholderText("Filter reviewers"), { target: { value: "rev" } });
     fireEvent.click(screen.getByRole("button", { name: /reviewer 1/i }));
     expect(screen.getByRole("button", { name: /remove reviewer 1/i })).toBeInTheDocument();
 
     metadataDeferred.resolve(metadata);
-    expect(await screen.findByDisplayValue("Manual PR title")).toBeInTheDocument();
+    expect(await screen.findByDisplayValue("AI title")).toBeInTheDocument();
+    const bodyInput = screen.getByLabelText(/body/i) as HTMLTextAreaElement;
+    expect(bodyInput.value).toContain("## Summary");
+    expectMetadataLoadingCleared();
+    expect(screen.getByRole("button", { name: "Create PR" })).toBeEnabled();
   });
 
   it("keeps submit disabled while preflight is pending or failed", async () => {
@@ -448,13 +473,20 @@ describe("PrCreateModal", () => {
     expect(screen.getByRole("button", { name: "Create PR" })).toBeDisabled();
   });
 
-  it("keeps metadata failure scoped so the modal remains usable", async () => {
-    mocks.generatePrMetadata.mockRejectedValueOnce(new Error("metadata blew up"));
+  it("clears metadata loading affordance into the error and manual fallback state", async () => {
+    const metadataDeferred = createDeferred<typeof metadata>();
+    mocks.generatePrMetadata.mockReturnValueOnce(metadataDeferred.promise);
     renderModal();
 
+    expect(await screen.findByText("Branch pushed to remote")).toBeInTheDocument();
+    expectMetadataLoadingAffordance();
+
+    metadataDeferred.reject(new Error("metadata blew up"));
+
     expect(await screen.findByText("metadata blew up")).toBeInTheDocument();
     expect(screen.getByText("Branch pushed to remote")).toBeInTheDocument();
     expect(screen.getByLabelText(/base branch/i)).toBeEnabled();
+    expectMetadataLoadingCleared();
 
     const bodyInput = screen.getByLabelText(/body/i) as HTMLTextAreaElement;
     expect(bodyInput.value).toContain("## Summary");
@@ -550,7 +582,7 @@ describe("PrCreateModal", () => {
     expect(screen.getByLabelText(/base branch/i)).toBeDisabled();
   });
 
-  it("regenerates AI content without re-blocking preflight and options", async () => {
+  it("regenerates AI content without re-blocking preflight and options while restoring the loading affordance", async () => {
     const regenerateDeferred = createDeferred<typeof metadata>();
     mocks.generatePrMetadata.mockResolvedValueOnce(metadata).mockReturnValueOnce(regenerateDeferred.promise);
     await renderModalLoaded();
@@ -560,9 +592,13 @@ describe("PrCreateModal", () => {
     fireEvent.click(screen.getAllByRole("button", { name: /^regenerate$/i })[0]);
     expect(screen.getByText("Branch pushed to remote")).toBeInTheDocument();
     expect(screen.getByLabelText(/base branch/i)).toBeEnabled();
-    expect(screen.getByText(/generating ai title/i)).toBeInTheDocument();
+    expectMetadataLoadingAffordance();
+    expect(screen.getByRole("button", { name: "Create PR" })).toBeDisabled();
+    fireEvent.click(screen.getByRole("button", { name: "Create PR" }));
+    expect(mocks.createPr).not.toHaveBeenCalled();
     regenerateDeferred.resolve({ title: "New title", body: "New body", templateUsed: false });
     await screen.findByDisplayValue("New title");
+    expectMetadataLoadingCleared();
     fireEvent.change(screen.getByDisplayValue("New title"), { target: { value: "edited" } });
     fireEvent.click(screen.getByRole("button", { name: /revert to ai version/i }));
     expect(screen.getByDisplayValue("New title")).toBeInTheDocument();
diff --git a/packages/dashboard/src/__tests__/pr-metadata-generator.test.ts b/packages/dashboard/src/__tests__/pr-metadata-generator.test.ts
index a3d314ddd0..1fab342b17 100644
--- a/packages/dashboard/src/__tests__/pr-metadata-generator.test.ts
+++ b/packages/dashboard/src/__tests__/pr-metadata-generator.test.ts
@@ -30,7 +30,7 @@ vi.mock("@fusion/engine", () => ({
 }));
 
 import { createFnAgent } from "@fusion/engine";
-import { generatePrMetadata } from "../pr-metadata-generator.js";
+import { generatePrMetadata, PR_METADATA_SYSTEM_PROMPT } from "../pr-metadata-generator.js";
 
 function createTask(): Task {
   return {
@@ -71,11 +71,7 @@ function capturedSystemPrompt(): string {
   return call?.systemPrompt ?? "";
 }
 
-const BASE_PR_METADATA_SYSTEM_PROMPT = [
-  "Generate GitHub PR metadata.",
-  "Respond with strict JSON only.",
-  "Schema: {title, summary, changes, testing, linkedTask}",
-].join("\n");
+const BASE_PR_METADATA_SYSTEM_PROMPT = PR_METADATA_SYSTEM_PROMPT;
 
 describe("generatePrMetadata", () => {
   let repoRoot: string;
@@ -148,7 +144,8 @@ describe("generatePrMetadata", () => {
     });
 
     expect(capturedSystemPrompt()).toBe(BASE_PR_METADATA_SYSTEM_PROMPT);
-    expect(capturedSystemPrompt()).toContain("Schema: {title, summary, changes, testing, linkedTask}");
+    expect(capturedSystemPrompt()).toContain("\"title\": string");
+    expect(capturedSystemPrompt()).toContain("\"linkedTask\": string");
     expect(result.title).toBe("feat: add routes");
     expect(result.body).toContain("## Summary");
   });
@@ -213,6 +210,39 @@ describe("generatePrMetadata", () => {
     expect(result.body).toContain("## Testing");
   });
 
+  it("sends the upgraded prompt contract and keeps all context inputs", async () => {
+    await generatePrMetadata({
+      task: createTask(),
+      repoRoot,
+      settings: {
+        titleSummarizerProvider: "anthropic",
+        titleSummarizerModelId: "claude-haiku",
+      } as never,
+    });
+
+    expect(PR_METADATA_SYSTEM_PROMPT).toContain("STRICT JSON ONLY");
+    expect(PR_METADATA_SYSTEM_PROMPT).toContain("conventional-commit style");
+    expect(PR_METADATA_SYSTEM_PROMPT).toContain("at most 72 characters");
+    expect(PR_METADATA_SYSTEM_PROMPT).toContain("commit log and diff stat first");
+    for (const field of ["title", "summary", "changes", "testing", "linkedTask"]) {
+      expect(PR_METADATA_SYSTEM_PROMPT).toContain(field);
+    }
+    expect(vi.mocked(createFnAgent)).toHaveBeenCalledWith(
+      expect.objectContaining({
+        systemPrompt: PR_METADATA_SYSTEM_PROMPT,
+      }),
+    );
+
+    const contextPrompt = promptMock.mock.calls[0]?.[0] as string;
+    expect(contextPrompt).toContain("Ground the PR title, summary, changes, and testing in the commit log and diff stat");
+    expect(contextPrompt).toContain("Task ID: FN-4991");
+    expect(contextPrompt).toContain("Task title: Route contracts");
+    expect(contextPrompt).toContain("Task description: Implement route contracts");
+    expect(contextPrompt).toContain("Commit log (source of truth):\n\ncommit");
+    expect(contextPrompt).toContain("Diff stat (source of truth):\n\n1 file changed");
+    expect(contextPrompt).toContain("Task prompt (supporting context):\n\n# Prompt");
+  });
+
   it("fills known sections when template exists and preserves unknown headings", async () => {
     mkdirSync(join(repoRoot, ".github"), { recursive: true });
     writeFileSync(
diff --git a/packages/dashboard/src/pr-metadata-generator.ts b/packages/dashboard/src/pr-metadata-generator.ts
index e70ee8ed4c..93c10a16a7 100644
--- a/packages/dashboard/src/pr-metadata-generator.ts
+++ b/packages/dashboard/src/pr-metadata-generator.ts
@@ -9,6 +9,22 @@ import { createFnAgent, resolveMcpServersForStore } from "@fusion/engine";
 const execAsync = promisify(execCb);
 export const PR_METADATA_TIMEOUT_MS = 60_000;
 
+/*
+FNXC:PrMetadataGeneration 2026-06-28-00:09:
+The Create PR AI prompt must produce operator-ready metadata grounded in the commit log and diff stat while preserving the strict JSON schema consumed by parseAiResult, buildBody, and fillTemplate. Keep the schema stable so later configurable-prompt work can reuse this default without changing downstream body assembly.
+*/
+export const PR_METADATA_SYSTEM_PROMPT = [
+  "You generate GitHub pull request metadata for Fusion tasks.",
+  "Respond with STRICT JSON ONLY: no markdown fences, no commentary, no prose outside the JSON object.",
+  "Use exactly this schema: {\"title\": string, \"summary\": string, \"changes\": string, \"testing\": string, \"linkedTask\": string}.",
+  "Title: concise imperative conventional-commit style, at most 72 characters, no trailing period, with a scope when the change clearly suggests one.",
+  "Summary: 1-3 short plain-sentence paragraphs explaining what changed and why; be specific and avoid marketing fluff.",
+  "Changes: a tight markdown bullet list of concrete, verifiable changes supported by the commit log or diff stat; do not speculate.",
+  "Testing: markdown bullets naming actual verification shown in the evidence; if no testing evidence exists, say '- Not provided.' or '- Not run (not provided).'.",
+  "LinkedTask: set to the task ID exactly as provided.",
+  "Ground every field in the commit log and diff stat first, then use the task title, task description, and task prompt only as supporting context.",
+].join("\n");
+
 export interface GeneratedPrMetadata {
   title: string;
   body: string;
@@ -270,11 +286,7 @@ export async function generatePrMetadata(input: {
     const template = templateExists ? await raceWithAbort(readFile(templatePath, "utf8"), combinedSignal) : "";
 
     const model = resolveTitleSummarizerSettingsModel(settings as Partial<Settings>);
-    const systemPrompt = [
-      "Generate GitHub PR metadata.",
-      "Respond with strict JSON only.",
-      "Schema: {title, summary, changes, testing, linkedTask}",
-    ];
+    const systemPrompt = [PR_METADATA_SYSTEM_PROMPT];
     const titleGuidance = settings.prTitlePromptInstructions?.trim();
     const descriptionGuidance = settings.prDescriptionPromptInstructions?.trim();
     /*
@@ -307,15 +319,20 @@ export async function generatePrMetadata(input: {
 
     try {
       const contextPrompt = [
+        "Source-of-truth guidance:",
+        "- Ground the PR title, summary, changes, and testing in the commit log and diff stat below.",
+        "- Use task title, task description, and task prompt only to clarify intent when the git evidence supports it.",
+        "- Omit speculation; when evidence for testing or a change is absent, say so instead of inventing details.",
+        "- Return only strict JSON matching the required schema.",
         `Task ID: ${task.id}`,
         `Task title: ${task.title}`,
         `Task description: ${task.description ?? ""}`,
         `Base branch: ${baseBranch}`,
-        "Commit log:",
+        "Commit log (source of truth):",
         logOut || "(none)",
-        "Diff stat:",
+        "Diff stat (source of truth):",
         diffStatOut || "(none)",
-        "Task prompt:",
+        "Task prompt (supporting context):",
         promptContent || "(none)",
       ].join("\n\n");