feat(ai_review): parse .pr-review.json:static_message + render as banner

Repos can pin a free-text notice (e.g. 'this repo is in maintenance mode',
or 'reviewers: focus on the public API only for this quarter') in
.pr-review.json:static_message. The string is stripped and capped at 400
chars (mirror of the existing instructions cap), then rendered as a
Markdown blockquote (> {msg}) directly under the REVIEW_HEADER so it
surfaces on every review without scrolling.

Plumbing: parse_repo_config exposes 'static_message'; format_review_body
accepts a static_message kwarg and inserts the blockquote before the
'### Summary of Changes' section; review_pr threads
config.get('static_message') to both call sites (salvage path + happy
path). Empty / non-string values are silently dropped, mirroring the
parser's 'ignore blank' handling for every other text field.

pilot/ai_review.py

@@ -215,12 +215,16 @@ def format_review_body(
     risks: list[str] | None = None,
     findings_for_table: list[dict] | None = None,
     inline_count: int = 0,
+    static_message: str = "",
 ) -> str:
     """Format the posted review summary body.
 
     Layout (per the operator's format guide):
 
       * Header line (``🤖 AI Review …``).
+      * Optional static banner (``> {static_message}``) — repo-wide call-out
+        from `.pr-review.json:static_message`, placed under the header so
+        every reviewer sees it on every review without scrolling.
       * **Summary of Changes** — 2–4 bullets of what the PR introduces
         (`summary_changes`); falls back to the opencode prose `summary` if
         the agent didn't emit the list.
@@ -241,6 +245,11 @@ def format_review_body(
     header = REVIEW_HEADER.format(model=model, sha=sha[:8] if sha else "unknown")
     parts: list[str] = [header]
 
+    # Optional free-text banner. Rendered as a Markdown blockquote immediately
+    # after the header — front-of-mind for any maintainer scanning the review.
+    if static_message and static_message.strip():
+        parts.append(f"> {static_message.strip()}")
+
     # --- Summary of Changes ---
     sc = list(summary_changes or [])
     if not sc and summary:
@@ -1137,6 +1146,7 @@ CONFIG_MAX_ITEM_CHARS = 200
 CONFIG_MAX_INSTRUCTIONS_CHARS = 4000
 CONFIG_MAX_PATTERNS_ITEMS = 16  # allow + deny separately, total 32 entries
 CONFIG_MAX_FINDINGS = 30
+CONFIG_MAX_STATIC_MESSAGE_CHARS = 400  # free-text banner, mirror of instructions
 
 STYLES = frozenset(STYLE_DEFAULTS)
 SEVERITY_VALUES = frozenset(SEVERITIES)
@@ -1152,6 +1162,7 @@ def parse_repo_config(raw: str) -> dict:
 
     Recognised keys (all optional):
       focus, exclude_paths, languages, instructions    — text steer
+      static_message  ≤ CONFIG_MAX_STATIC_MESSAGE_CHARS — banner under header
       style          strict|balanced|lenient            — default: balanced
       severity_threshold low|medium|high|critical       — default: per style
       max_findings   1..CONFIG_MAX_FINDINGS              — default: per style
@@ -1185,6 +1196,10 @@ def parse_repo_config(raw: str) -> dict:
     if isinstance(instr, str) and instr.strip():
         out["instructions"] = instr.strip()[:CONFIG_MAX_INSTRUCTIONS_CHARS]
 
+    sm = data.get("static_message")
+    if isinstance(sm, str) and sm.strip():
+        out["static_message"] = sm.strip()[:CONFIG_MAX_STATIC_MESSAGE_CHARS]
+
     style = data.get("style")
     if isinstance(style, str) and style.strip().lower() in STYLES:
         out["style"] = style.strip().lower()
@@ -1945,7 +1960,8 @@ def review_pr(
                 usage_section = _render_collapsible_usage(usage, display_model, config=config) if report_usage else ""
                 post_review(api, repo, index, token, format_review_body(
                     salvaged or "AI review produced no parseable output.",
-                    display_model, sha, usage_section=usage_section))
+                    display_model, sha, usage_section=usage_section,
+                    static_message=(config or {}).get("static_message", "")))
                 return True
         else:
             user_prompt = build_user_prompt(title, body + compression_note, diff, config, prior, additional_context)
@@ -2015,6 +2031,7 @@ def review_pr(
             risks=risks,
             findings_for_table=findings,
             inline_count=len(anchored),
+            static_message=(config or {}).get("static_message", ""),
         )
 
         post_inline_review(api, repo, index, token, summary_body, anchored)

tests/pilot/test_ai_review.py

@@ -401,6 +401,24 @@ def test_parse_repo_config_partial_and_bad():
     assert parse_repo_config('{"instructions":"   "}') == {}
 
 
+def test_parse_repo_config_reads_static_message():
+    cfg = parse_repo_config(json.dumps({"static_message": "  NOTE: this repo is in maintenance mode  "}))
+    assert cfg == {"static_message": "NOTE: this repo is in maintenance mode"}
+
+
+def test_parse_repo_config_static_message_caps_length():
+    long_text = "x" * 9999
+    cfg = parse_repo_config(json.dumps({"static_message": long_text}))
+    assert "static_message" in cfg
+    assert len(cfg["static_message"]) <= 400
+
+
+def test_parse_repo_config_static_message_ignores_blank():
+    assert "static_message" not in parse_repo_config(json.dumps({"static_message": "   "}))
+    assert "static_message" not in parse_repo_config(json.dumps({"static_message": ""}))
+    assert "static_message" not in parse_repo_config(json.dumps({"static_message": 42}))
+
+
 # ---------------------------------------------------------------------------
 # dedupe / prior-context parsing
 # ---------------------------------------------------------------------------
@@ -823,6 +841,22 @@ def test_format_review_body_no_usage_section_omitted():
     assert "AI usage" not in body
 
 
+def test_format_review_body_renders_static_message_banner():
+    body = format_review_body(
+        "", "glm-5.2:cloud", "abcdef1234567890",
+        static_message="NOTE: this repo is in maintenance mode.",
+    )
+    assert "> NOTE: this repo is in maintenance mode." in body
+    # Banner sits under the header and above the rest of the body.
+    assert body.index("NOTE") > body.index("🤖")
+    assert body.index("NOTE") < body.index("### Summary of Changes")
+
+
+def test_format_review_body_omits_static_message_when_blank():
+    body = format_review_body("", "glm-5.2:cloud", "abcdef1234567890")
+    assert "> " not in body
+
+
 def test_format_review_body_with_summary_changes_and_risks():
     body = format_review_body(
         "", "glm-5.2:cloud", "abcdef1234567890",