feat: director prompt render-style switch (markdown default, xml experiment)

src/agent/directors/prompt-sections.test.ts

@@ -0,0 +1,124 @@
+import { afterEach, describe, expect, test } from "bun:test";
+
+import { DIRECTOR_REGISTRY } from "./registry.js";
+import { DIRECTOR_IDS } from "./types.js";
+import { formatDirectorSystemPrompt } from "./identity.js";
+import {
+  FALLBACK_SECTION_TAG,
+  normalizeSectionTag,
+  PROMPT_RENDER_STYLE_ENV_VAR,
+  PROMPT_SECTION_TAG_VOCABULARY,
+  renderDirectorSystemPrompt,
+  renderPromptBody,
+  resetCachedPromptRenderStyleForTests,
+  resolvePromptRenderStyle,
+  splitPromptSections,
+  tagForSectionTitle,
+} from "./prompt-sections.js";
+
+const savedEnv = process.env[PROMPT_RENDER_STYLE_ENV_VAR];
+
+afterEach(() => {
+  // "" resolves like unset (markdown); `delete` on a computed key is
+  // lint-banned, so an empty assignment stands in for a missing var.
+  process.env[PROMPT_RENDER_STYLE_ENV_VAR] = savedEnv ?? "";
+  resetCachedPromptRenderStyleForTests();
+});
+
+function tagNames(xml: string): string[] {
+  return [...xml.matchAll(/<([a-z][a-z0-9_]*)>/g)].map((m) => m[1] ?? "");
+}
+
+describe("director prompt render style", () => {
+  test("default arm is byte-identical to formatDirectorSystemPrompt for every director", () => {
+    process.env[PROMPT_RENDER_STYLE_ENV_VAR] = "";
+    resetCachedPromptRenderStyleForTests();
+    for (const id of DIRECTOR_IDS) {
+      const pkg = DIRECTOR_REGISTRY[id];
+      expect(renderDirectorSystemPrompt(pkg)).toBe(
+        formatDirectorSystemPrompt(pkg),
+      );
+      expect(renderDirectorSystemPrompt(pkg, "markdown")).toBe(
+        formatDirectorSystemPrompt(pkg),
+      );
+      expect(renderPromptBody(pkg.systemPrompt, "markdown")).toBe(
+        pkg.systemPrompt,
+      );
+    }
+  });
+
+  test("xml arm keeps balanced tags with one counterpart per markdown section", () => {
+    for (const id of DIRECTOR_IDS) {
+      const pkg = DIRECTOR_REGISTRY[id];
+      const full = formatDirectorSystemPrompt(pkg);
+      const xml = renderDirectorSystemPrompt(pkg, "xml");
+      const { sections } = splitPromptSections(full);
+      if (sections.length === 0) {
+        // Section-less directors render identically in both arms.
+        expect(xml).toBe(full);
+        continue;
+      }
+      // Every markdown section has exactly one xml counterpart.
+      expect(tagNames(xml)).toHaveLength(sections.length);
+      // Balanced: every open has its close, no heading lines survive.
+      for (const tag of new Set(tagNames(xml))) {
+        const opens = xml.split(`<${tag}>`).length - 1;
+        const closes = xml.split(`</${tag}>`).length - 1;
+        expect(opens).toBeGreaterThan(0);
+        expect(closes).toBe(opens);
+      }
+      expect(xml).not.toMatch(/^#{1,2} /m);
+      // Fixed vocabulary: every emitted tag is known or the fallback.
+      const known = new Set<string>([
+        ...PROMPT_SECTION_TAG_VOCABULARY,
+        FALLBACK_SECTION_TAG,
+      ]);
+      for (const tag of tagNames(xml)) expect(known.has(tag)).toBe(true);
+    }
+  });
+
+  test("fixed vocabulary covers every shipped section title", () => {
+    const known: ReadonlySet<string> = new Set(PROMPT_SECTION_TAG_VOCABULARY);
+    for (const id of DIRECTOR_IDS) {
+      const { sections } = splitPromptSections(
+        formatDirectorSystemPrompt(DIRECTOR_REGISTRY[id]),
+      );
+      for (const section of sections) {
+        expect(known.has(tagForSectionTitle(section.title))).toBe(true);
+      }
+    }
+  });
+
+  test("style resolves once per session and defaults to markdown", () => {
+    process.env[PROMPT_RENDER_STYLE_ENV_VAR] = "";
+    resetCachedPromptRenderStyleForTests();
+    expect(resolvePromptRenderStyle()).toBe("markdown");
+
+    process.env[PROMPT_RENDER_STYLE_ENV_VAR] = "xml";
+    resetCachedPromptRenderStyleForTests();
+    expect(resolvePromptRenderStyle()).toBe("xml");
+    // Mid-session flips do not take effect: the cache prefix holds.
+    process.env[PROMPT_RENDER_STYLE_ENV_VAR] = "markdown";
+    expect(resolvePromptRenderStyle()).toBe("xml");
+
+    process.env[PROMPT_RENDER_STYLE_ENV_VAR] = "no-such-style";
+    resetCachedPromptRenderStyleForTests();
+    expect(resolvePromptRenderStyle()).toBe("markdown");
+  });
+
+  test("normalizeSectionTag handles digits, punctuation, and empties", () => {
+    expect(normalizeSectionTag("Prerequisites")).toBe("prerequisites");
+    expect(normalizeSectionTag("0. Document discovery")).toBe(
+      "sec_0_document_discovery",
+    );
+    expect(
+      normalizeSectionTag(
+        "If IMPLEMENTATION → DIY when tiny; spawn when substantial",
+      ),
+    ).toBe("if_implementation_diy_when_tiny_spawn_when_substantial");
+    expect(normalizeSectionTag("")).toBe(FALLBACK_SECTION_TAG);
+    expect(tagForSectionTitle("a title no package uses")).toBe(
+      FALLBACK_SECTION_TAG,
+    );
+  });
+});

src/agent/directors/prompt-sections.ts

@@ -0,0 +1,242 @@
+// Section registry for director prompt assembly (CL-8685 render-style experiment).
+//
+// Every director system prompt is a preamble plus `#`/`##` sections. The
+// markdown arm renders sections as `## Title` (byte-identical to the shipped
+// prompts — the markdown path returns `formatDirectorSystemPrompt` untouched);
+// the xml arm renders those same sections as `<tag>body</tag>` with a tag
+// from the fixed vocabulary below. Tags wrap whole sections only: inline
+// prose, deeper sub-headings (`###` and below pass through verbatim), and the
+// identity header (no `#` headings, so it stays preamble) are never tagged.
+//
+// Switch: `CORBITS_PROMPT_RENDER_STYLE=markdown|xml` (default `markdown`).
+// The style resolves once per process and is cached, so the prompt-cache
+// prefix cannot split mid-session. Tests reset the cache via
+// `resetCachedPromptRenderStyleForTests`.
+
+import type { DirectorPackage } from "./types.js";
+import { formatDirectorSystemPrompt } from "./identity.js";
+
+export type PromptRenderStyle = "markdown" | "xml";
+
+/** Environment variable selecting the director-prompt render style. */
+export const PROMPT_RENDER_STYLE_ENV_VAR = "CORBITS_PROMPT_RENDER_STYLE";
+
+// Fixed tag vocabulary: one tag per `#`/`##` section title shipped in
+// `src/agent/directors/*/package.ts`, normalized as `normalizeSectionTag`
+// does. Titles outside this set (future packages) fall back to `section`.
+export const PROMPT_SECTION_TAG_VOCABULARY = [
+  "acknowledgment",
+  "actually_overall_assessment",
+  "anti_cascade_stall_dig_diagnose",
+  "architecture_recommendations_all_terrible",
+  "architecture_review_criteria",
+  "blockers",
+  "build_a_shared_glossary",
+  "build_gate",
+  "capabilities",
+  "cargo_cult_programming_patterns_you_re_missing",
+  "case_template",
+  "common_neckbeard_phrases",
+  "corbits_report_shape",
+  "critical_reminder",
+  "cross_document_analysis",
+  "design_in_report_workflow",
+  "document_discovery",
+  "document_types",
+  "documents_not_found",
+  "effort_scaling_implementation_orchestration",
+  "error_handling",
+  "execution_steps",
+  "fetch_urls_primary_mounted",
+  "final_recommendation",
+  "findings",
+  "findings_route_to_follow_ups_never_silent_retunes",
+  "guidelines",
+  "harness_consume_do_not_build_a_second_one",
+  "hold_the_line_on_scope",
+  "how_you_work",
+  "if_communication_answer_directly",
+  "if_implementation_diy_when_tiny_spawn_when_substantial",
+  "if_orchestration_coordinate",
+  "implement_and_test",
+  "implementation_review_criteria",
+  "incomplete_document_set",
+  "insufferable_details_x_found",
+  "insufferable_mode_default",
+  "key_suggestions_all_terrible",
+  "maddening_nitpicks_x_found",
+  "malformed_documents",
+  "neckbeard_perspective",
+  "neckbeard_review_project_name",
+  "neckbeard_review_project_name_maximum_pedantry_edition",
+  "non_negotiables",
+  "operator_updates_mandatory_while_fleet_is_live",
+  "out_of_lane",
+  "parent_tools",
+  "paths",
+  "peak_neckbeard_issues_x_found",
+  "plan",
+  "prerequisites",
+  "product_review_criteria",
+  "protocol_in_order_no_shortcuts",
+  "push_back_on_the_vision_itself_gently",
+  "recommendation",
+  "remember",
+  "report",
+  "report_contract",
+  "report_shape",
+  "report_when_dispatched_as_a_worker",
+  "reporting_back",
+  "request_shape_implementation_orchestration_communication",
+  "review_framework",
+  "review_modes",
+  "riff_first",
+  "risk_prioritization",
+  "rules",
+  "sec_0_document_discovery",
+  "sec_1_analyze_and_classify_input",
+  "sec_2_route_and_deepen",
+  "sec_3_update_document",
+  "sec_4_cross_document_consistency_significant_only",
+  "sec_5_gap_detection_significant_only",
+  "sec_6_report",
+  "session_initialization",
+  "spawn_graph",
+  "spawn_handoff",
+  "stay_in_lane",
+  "step_1_load_prerequisites",
+  "step_2_discover_documents_and_code_when_asked",
+  "step_3_determine_review_mode",
+  "step_4_read_all_targets",
+  "step_5_perform_analysis",
+  "step_6_synthesize_nitpicks",
+  "step_7_report_nitpicks",
+  "summary",
+  "tools",
+  "unbearable_issues_x_found",
+  "utterly_unbearable_mode",
+  "verify_after_ship",
+  "voice",
+  "what_to_measure",
+  "what_you_do_not_do",
+  "who_you_are",
+  "workflow_scribe_core",
+  "write_the_brief_when_it_is_ready",
+  "your_role",
+] as const;
+
+const SECTION_TAG_SET: ReadonlySet<string> = new Set(
+  PROMPT_SECTION_TAG_VOCABULARY,
+);
+
+/** Fallback tag for section titles outside the fixed vocabulary. */
+export const FALLBACK_SECTION_TAG = "section";
+
+export interface PromptSection {
+  readonly title: string;
+  readonly level: 1 | 2;
+  readonly body: string;
+}
+
+export interface SplitPrompt {
+  readonly preamble: string;
+  readonly sections: readonly PromptSection[];
+}
+
+// Section boundary: an ATX `#` or `##` heading line. `###` and deeper are
+// sub-section detail and never split — tags stay at section granularity.
+const SECTION_HEADING_PATTERN = /^#{1,2} ([^\n]*)(?:\n|$)/gm;
+
+/** Split prompt text into its preamble and `#`/`##` sections (offsets preserved). */
+export function splitPromptSections(text: string): SplitPrompt {
+  const matches = [...text.matchAll(SECTION_HEADING_PATTERN)];
+  if (matches.length === 0) return { preamble: text, sections: [] };
+  const first = matches[0];
+  if (first === undefined || first.index === undefined)
+    return { preamble: text, sections: [] };
+  const preamble = text.slice(0, first.index);
+  const sections = matches.map((match, i) => {
+    const level = match[0].startsWith("## ") ? 2 : 1;
+    const next = matches[i + 1];
+    const bodyStart = (match.index ?? 0) + match[0].length;
+    const bodyEnd = next?.index ?? text.length;
+    return {
+      title: (match[1] ?? "").trim(),
+      level: level as 1 | 2,
+      body: text.slice(bodyStart, bodyEnd),
+    };
+  });
+  return { preamble, sections };
+}
+
+// Normalize a section title to its tag: lowercase, runs of non-alphanumerics
+// to `_`, trimmed. Leading-digit results take a `sec_` prefix (bare digits
+// are not valid XML tag starts); empty results take the fallback tag.
+export function normalizeSectionTag(title: string): string {
+  const base = title
+    .toLowerCase()
+    .replace(/[^a-z0-9]+/g, "_")
+    .replace(/^_+|_+$/g, "");
+  if (base === "") return FALLBACK_SECTION_TAG;
+  return /^[0-9]/.test(base) ? `sec_${base}` : base;
+}
+
+/** Map a section title to its render tag: vocabulary hit, else the fallback. */
+export function tagForSectionTitle(title: string): string {
+  const tag = normalizeSectionTag(title);
+  return SECTION_TAG_SET.has(tag) ? tag : FALLBACK_SECTION_TAG;
+}
+
+/**
+ * Render prompt text in a style. Markdown returns the input untouched
+ * (byte-identical by construction); xml wraps each section body in its tag.
+ */
+export function renderPromptBody(
+  text: string,
+  style: PromptRenderStyle,
+): string {
+  if (style === "markdown") return text;
+  const { preamble, sections } = splitPromptSections(text);
+  if (sections.length === 0) return text;
+  const parts = preamble.trim() === "" ? [] : [preamble.trim()];
+  for (const section of sections) {
+    const tag = tagForSectionTitle(section.title);
+    parts.push(`<${tag}>\n${section.body.trim()}\n</${tag}>`);
+  }
+  return parts.join("\n\n");
+}
+
+let cachedStyle: PromptRenderStyle | undefined;
+
+/**
+ * Resolve the render style once per process and cache it: the director prompt
+ * prefix must not change mid-session or the prompt cache splits. Unknown and
+ * absent values fall back to markdown.
+ */
+export function resolvePromptRenderStyle(
+  env: Record<string, string | undefined> = process.env,
+): PromptRenderStyle {
+  if (cachedStyle === undefined) {
+    const raw = env[PROMPT_RENDER_STYLE_ENV_VAR]?.trim().toLowerCase();
+    cachedStyle = raw === "xml" ? "xml" : "markdown";
+  }
+  return cachedStyle;
+}
+
+/** Test-only reset for the once-per-session style cache. */
+export function resetCachedPromptRenderStyleForTests(): void {
+  cachedStyle = undefined;
+}
+
+/**
+ * Render a director package system prompt (identity header + body) in a
+ * style. The default arm resolves the once-per-session style; markdown is
+ * `formatDirectorSystemPrompt` verbatim.
+ */
+export function renderDirectorSystemPrompt(
+  pkg: DirectorPackage,
+  style: PromptRenderStyle = resolvePromptRenderStyle(),
+): string {
+  const full = formatDirectorSystemPrompt(pkg);
+  return style === "xml" ? renderPromptBody(full, "xml") : full;
+}

src/agent/directors/registry.ts

@@ -19,7 +19,7 @@ import { testsmithPackage } from "./testsmith/package.js";
 import { gauntletPackage } from "./gauntlet/package.js";
 import { proberPackage } from "./prober/package.js";
 import { wardenPackage } from "./warden/package.js";
-import { formatDirectorSystemPrompt } from "./identity.js";
+import { renderDirectorSystemPrompt } from "./prompt-sections.js";
 import {
   DIRECTOR_IDS,
   type DirectorId,
@@ -144,7 +144,7 @@ export function packageToProfile(pkg: DirectorPackage): AgentProfile {
   return {
     id: pkg.id,
     description: `${pkg.description} (agent id: ${pkg.id})`,
-    systemPromptRole: formatDirectorSystemPrompt(pkg),
+    systemPromptRole: renderDirectorSystemPrompt(pkg),
     // Nested spawn is still gated by allowOrchestrator on the parent fleet tools.
     // Skywalker maySpawn marks intent; leaves stay non-orchestrator.
     orchestrator: pkg.spawn.maySpawn,