fix(inject-context): stop dumping Kimi rules corpus and AGENTS.md into terminal

src/runtime/inject-context.ts

@@ -22,13 +22,37 @@ export function claudeMdKey(prompt: string, ctx: string): string {
   return `claude-md:${hashText(prompt)}:${hashText(ctx)}`;
 }
 
+/**
+ * Extract the APEX preamble portion of a `buildClaudeMdContext` result, i.e.
+ * everything BEFORE the `# <docName>\n` root-doc block it prepends on dev
+ * prompts. Returns "" when `ctx` has no preamble (plain prompt: `ctx` starts
+ * directly with the root-doc heading).
+ * @param ctx - The full `buildClaudeMdContext` return value.
+ * @param docName - Root doc file name (e.g. "AGENTS.md").
+ * @returns The preamble text, or "" when absent.
+ */
+function extractApexPreamble(ctx: string, docName: string): string {
+  const heading = `# ${docName}\n`;
+  if (ctx.startsWith(heading)) return "";
+  const sep = `\n\n${heading}`;
+  const idx = ctx.indexOf(sep);
+  return idx === -1 ? "" : ctx.slice(0, idx);
+}
+
 /**
  * UserPromptSubmit context injection: render the CLAUDE.md (+ optional APEX)
  * preamble as a Claude `additionalContext` response, or "" when nothing to emit.
  * Guarded by {@link oncePerWindow} via {@link claudeMdKey}: only a
  * near-simultaneous double-fire of the SAME turn (identical prompt AND identical
  * block, within {@link DEDUP_WINDOW_MS}) is suppressed. The invariant "CLAUDE.md
  * is emitted on EVERY message" is thus preserved.
+ *
+ * On kimi specifically, the root doc body is dropped from the emitted text:
+ * Kimi loads `<kimiHome>/AGENTS.md` natively at session start (`apex-target.ts`),
+ * so re-injecting its full body on every prompt is redundant terminal noise
+ * (kimi has no model-only hook channel — `runtime/inform.ts`). The APEX
+ * preamble, which is NOT part of `AGENTS.md`, is still emitted in full when the
+ * prompt is dev-shaped; a plain prompt leaves only the notice.
  * @param prompt - The raw user prompt.
  * @param cwd - Project root (for project-type detection).
  * @param id - Harness target id (defaults to "claude-code" — zero-regression default).
@@ -38,7 +62,12 @@ export function promptSubmitContext(prompt: string, cwd: string, id: string = "c
   const ctx = buildClaudeMdContext(prompt, cwd, id);
   if (!ctx) return "";
   if (!oncePerWindow(claudeMdKey(prompt, ctx), DEDUP_WINDOW_MS)) return "";
-  return renderInform(id, "UserPromptSubmit", ctx, `${apexDocName(id)} injected`);
+  const notice = `${apexDocName(id)} injected`;
+  if (id === "kimi") {
+    const preamble = extractApexPreamble(ctx, apexDocName(id));
+    return preamble ? renderInform(id, "UserPromptSubmit", preamble, notice) : notice;
+  }
+  return renderInform(id, "UserPromptSubmit", ctx, notice);
 }
 
 /**

src/runtime/lifecycle/inject-rules.ts

@@ -1,6 +1,7 @@
 import { existsSync, readdirSync, readFileSync } from "node:fs";
 import { join } from "node:path";
 import { renderInform } from "../inform";
+import { rulesInAgentsMd } from "./kimi-rules-native";
 
 /** Read & concatenate all `*.md` files (sorted) under `rulesDir`. */
 export function readRules(rulesDir: string): string {
@@ -29,12 +30,21 @@ export function readRules(rulesDir: string): string {
  * with the *actual* `hookEventName` — the spec requires it to match the firing
  * event (a hardcoded "SessionStart" is non-conforming and may be dropped on
  * UserPromptSubmit/SubagentStart).
+ *
+ * On kimi's `UserPromptSubmit` specifically, when the corpus is already fenced
+ * inside `<kimiHome>/AGENTS.md` (native load, {@link rulesInAgentsMd}), only the
+ * notice is emitted — the re-injected corpus would otherwise dump into the
+ * user's terminal on every single prompt for no model-context benefit.
+ * `SessionStart`/`SubagentStart` always keep the full corpus (session bootstrap
+ * / sub-agent contexts need it regardless of the native AGENTS.md load).
  * @param pluginRoot - `CLAUDE_PLUGIN_ROOT` of the claude-rules plugin.
  * @param event - The firing hook event name (e.g. "SessionStart").
  * @param id - Harness target id (defaults to "claude-code" — zero-regression default).
  * @returns The native hook stdout (possibly empty).
  */
 export function injectRules(pluginRoot: string, event: string, id: string = "claude-code"): string {
   const content = readRules(join(pluginRoot, "rules"));
-  return content ? renderInform(id, event, content, "rules 00-08 injected") : "";
+  if (!content) return "";
+  if (id === "kimi" && event === "UserPromptSubmit" && rulesInAgentsMd()) return "rules 00-08 injected";
+  return renderInform(id, event, content, "rules 00-08 injected");
 }

src/runtime/lifecycle/kimi-rules-native.ts

@@ -0,0 +1,44 @@
+/**
+ * Guard for the kimi notice-only rules injection. Kimi Code CLI has no
+ * model-only hook channel (`src/runtime/inform.ts`) — every `UserPromptSubmit`
+ * stdout is BOTH appended to the model's context AND rendered raw in the
+ * user's terminal. `injectRules` (`inject-rules.ts`) normally re-injects the
+ * full ~18 Ko rules corpus on every prompt; when the installer has already
+ * merged that same corpus into `<kimiHome>/AGENTS.md` — which Kimi loads
+ * natively at session start via its documented `${agents_md}` mechanism,
+ * independent of hooks — the re-injection is pure noise the user has to
+ * scroll past. Confirmed present, fenced, in the local install:
+ * `~/.kimi-code/AGENTS.md:87` / `:335`.
+ *
+ * Fail-safe semantics: fences absent, file absent, or any read error ⟹
+ * `false` — the caller then falls back to the full corpus. A dump is
+ * verbose but never wrong; a false `true` would silently drop the rules.
+ */
+import { existsSync, readFileSync } from "node:fs";
+import { join } from "node:path";
+import { harnessHome } from "../../config/home-dir";
+
+/** Opening fence the fusengine installer writes around the merged corpus. */
+const FENCE_START = "<!-- fusengine:kimi-rules:start -->";
+
+/** Closing fence the fusengine installer writes around the merged corpus. */
+const FENCE_END = "<!-- fusengine:kimi-rules:end -->";
+
+/**
+ * Check whether the kimi rules corpus is already present, fenced, inside
+ * `<kimiHome>/AGENTS.md`.
+ * @param home - Kimi home dir override (defaults to `harnessHome("kimi")`,
+ * which honors `KIMI_CODE_HOME`).
+ * @returns `true` only when both fences are found in a readable file.
+ */
+export function rulesInAgentsMd(home?: string): boolean {
+  try {
+    const kimiHome = home ?? harnessHome("kimi");
+    const agentsMd = join(kimiHome, "AGENTS.md");
+    if (!existsSync(agentsMd)) return false;
+    const content = readFileSync(agentsMd, "utf-8");
+    return content.includes(FENCE_START) && content.includes(FENCE_END);
+  } catch {
+    return false;
+  }
+}

test/fixtures/inform-matrix.golden.json

@@ -0,0 +1,34 @@
+{
+  "injectRules|claude-code|SessionStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SessionStart\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|claude-code|SubagentStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SubagentStart\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|claude-code|UserPromptSubmit|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|codex|SessionStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SessionStart\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|codex|SubagentStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SubagentStart\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|codex|UserPromptSubmit|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|gemini-cli|SessionStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SessionStart\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|gemini-cli|SubagentStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SubagentStart\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|gemini-cli|UserPromptSubmit|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"# 00 alpha\\nalpha body\\n\\n\\n# 01 beta\\nbeta body\\n\"},\"systemMessage\":\"rules 00-08 injected\"}",
+  "injectRules|kimi|SessionStart|-": "# 00 alpha\nalpha body\n\n\n# 01 beta\nbeta body\n\n\nrules 00-08 injected",
+  "injectRules|kimi|SubagentStart|-": "# 00 alpha\nalpha body\n\n\n# 01 beta\nbeta body\n\n\nrules 00-08 injected",
+  "injectRules|kimi|UserPromptSubmit|-": "# 00 alpha\nalpha body\n\n\n# 01 beta\nbeta body\n\n\nrules 00-08 injected",
+  "lessons|claude-code|SessionStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SessionStart\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|claude-code|SubagentStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SubagentStart\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|claude-code|UserPromptSubmit|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|codex|SessionStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SessionStart\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|codex|SubagentStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SubagentStart\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|codex|UserPromptSubmit|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|gemini-cli|SessionStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SessionStart\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|gemini-cli|SubagentStart|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"SubagentStart\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|gemini-cli|UserPromptSubmit|-": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"Project lessons — never reproduce these:\\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\"},\"systemMessage\":\"lessons injected\"}",
+  "lessons|kimi|SessionStart|-": "Project lessons — never reproduce these:\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\n\nlessons injected",
+  "lessons|kimi|SubagentStart|-": "Project lessons — never reproduce these:\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\n\nlessons injected",
+  "lessons|kimi|UserPromptSubmit|-": "Project lessons — never reproduce these:\n- [2026-01-01 10:00] Fixture lesson body. → Fixture rule. [TRIGGERS keyword:fixture]\nYou may append OR refine/merge/dedupe bullets in MEMORY/LESSON.md — keep it terse.\n\nlessons injected",
+  "promptSubmit|claude-code|UserPromptSubmit|dev": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"INSTRUCTION: This is a development task. Use APEX methodology:\\n\\n**TRACKING FILE**: [project]/.claude/apex/task.json — create it yourself via apex-methodology Step 0 (init-tracking) if missing\\n\\n1. **ANALYZE** (MANDATORY - 3 AGENTS IN PARALLEL):\\n   - explore-codebase + research-expert + general-purpose (framework expertise)\\n   - Project type detected: generic\\n\\n2. **PLAN**: Use TaskCreate to break down tasks (<100 lines per file)\\n\\n3. **EXECUTE**: general-purpose, follow SOLID principles, split at 90 lines\\n\\n4. **eLICIT**: self-review with NAMED elicitation techniques (apex ref 03.5-elicit) — fix findings BEFORE validation\\n\\n5. **VERIFY**: functional check — run it, confirm references⇔declarations consistency\\n\\n6. **eXAMINE**: Run sniper agent after ANY modification\\n\\n**GATE**: eLicit + Verify BEFORE sniper — NEVER skip.\\n\\n**IMPORTANT**: Read .claude/apex/task.json to check documentation status before writing code.\\n\\n# CLAUDE.md\\n# fixture CLAUDE.md for .claude\\nBODY .claude\\n\"},\"systemMessage\":\"CLAUDE.md injected\"}",
+  "promptSubmit|claude-code|UserPromptSubmit|plain": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"# CLAUDE.md\\n# fixture CLAUDE.md for .claude\\nBODY .claude\\n\"},\"systemMessage\":\"CLAUDE.md injected\"}",
+  "promptSubmit|codex|UserPromptSubmit|dev": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"INSTRUCTION: This is a development task. Use APEX methodology:\\n\\n**TRACKING FILE**: [project]/.codex/apex/task.json — create it yourself via apex-methodology Step 0 (init-tracking) if missing\\n\\n1. **ANALYZE** (MANDATORY - 3 AGENTS IN PARALLEL):\\n   - explore-codebase + research-expert + general-purpose (framework expertise)\\n   - Project type detected: generic\\n\\n2. **PLAN**: Use update_plan to break down tasks (<100 lines per file)\\n\\n3. **EXECUTE**: general-purpose, follow SOLID principles, split at 90 lines\\n\\n4. **eLICIT**: self-review with NAMED elicitation techniques (apex ref 03.5-elicit) — fix findings BEFORE validation\\n\\n5. **VERIFY**: functional check — run it, confirm references⇔declarations consistency\\n\\n6. **eXAMINE**: Run sniper agent after ANY modification\\n\\n**GATE**: eLicit + Verify BEFORE sniper — NEVER skip.\\n\\n**IMPORTANT**: Read .codex/apex/task.json to check documentation status before writing code.\\n\\n# AGENTS.md\\n# fixture AGENTS.md for .codex\\nBODY .codex\\n\"},\"systemMessage\":\"AGENTS.md injected\"}",
+  "promptSubmit|codex|UserPromptSubmit|plain": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"# AGENTS.md\\n# fixture AGENTS.md for .codex\\nBODY .codex\\n\"},\"systemMessage\":\"AGENTS.md injected\"}",
+  "promptSubmit|gemini-cli|UserPromptSubmit|dev": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"INSTRUCTION: This is a development task. Use APEX methodology:\\n\\n**TRACKING FILE**: [project]/.gemini/apex/task.json — create it yourself via apex-methodology Step 0 (init-tracking) if missing\\n\\n1. **ANALYZE** (MANDATORY - 3 AGENTS IN PARALLEL):\\n   - explore-codebase + research-expert + general-purpose (framework expertise)\\n   - Project type detected: generic\\n\\n2. **PLAN**: Use TaskCreate to break down tasks (<100 lines per file)\\n\\n3. **EXECUTE**: general-purpose, follow SOLID principles, split at 90 lines\\n\\n4. **eLICIT**: self-review with NAMED elicitation techniques (apex ref 03.5-elicit) — fix findings BEFORE validation\\n\\n5. **VERIFY**: functional check — run it, confirm references⇔declarations consistency\\n\\n6. **eXAMINE**: Run sniper agent after ANY modification\\n\\n**GATE**: eLicit + Verify BEFORE sniper — NEVER skip.\\n\\n**IMPORTANT**: Read .gemini/apex/task.json to check documentation status before writing code.\\n\\n# CLAUDE.md\\n# fixture CLAUDE.md for .gemini\\nBODY .gemini\\n\"},\"systemMessage\":\"CLAUDE.md injected\"}",
+  "promptSubmit|gemini-cli|UserPromptSubmit|plain": "{\"hookSpecificOutput\":{\"hookEventName\":\"UserPromptSubmit\",\"additionalContext\":\"# CLAUDE.md\\n# fixture CLAUDE.md for .gemini\\nBODY .gemini\\n\"},\"systemMessage\":\"CLAUDE.md injected\"}",
+  "promptSubmit|kimi|UserPromptSubmit|dev": "INSTRUCTION: This is a development task. Use APEX methodology:\n\n**TRACKING FILE**: [project]/.kimi-code/apex/task.json — create it yourself via apex-methodology Step 0 (init-tracking) if missing\n\n1. **ANALYZE** (MANDATORY - 3 AGENTS IN PARALLEL):\n   - explore-codebase + research-expert + general-purpose (framework expertise)\n   - Project type detected: generic\n\n2. **PLAN**: Use TodoList to break down tasks (<100 lines per file)\n\n3. **EXECUTE**: general-purpose, follow SOLID principles, split at 90 lines\n\n4. **eLICIT**: self-review with NAMED elicitation techniques (apex ref 03.5-elicit) — fix findings BEFORE validation\n\n5. **VERIFY**: functional check — run it, confirm references⇔declarations consistency\n\n6. **eXAMINE**: Run sniper agent after ANY modification\n\n**GATE**: eLicit + Verify BEFORE sniper — NEVER skip.\n\n**IMPORTANT**: Read .kimi-code/apex/task.json to check documentation status before writing code.\n\nAGENTS.md injected",
+  "promptSubmit|kimi|UserPromptSubmit|plain": "AGENTS.md injected"
+}

test/helpers/capture-inform-golden.ts

@@ -0,0 +1,23 @@
+/**
+ * @module test/helpers/capture-inform-golden
+ * Manual, one-shot script: run `bun run test/helpers/capture-inform-golden.ts`
+ * to (re)write `test/fixtures/inform-matrix.golden.json` from the current
+ * `src/` behavior.
+ *
+ * NEVER re-run this in the same commit as a behavior change to `renderInform`
+ * (or anything it calls transitively). The golden is the WITNESS that the
+ * pre-change code respected the zero-regression theorem's hypotheses — it
+ * must be captured and committed BEFORE the change, as its own commit.
+ * Regenerating it alongside the change makes the proof and the change
+ * indistinguishable on review: a diff that "updates the golden" could just as
+ * easily be hiding a real regression as reflecting an intentional new branch.
+ */
+import { mkdirSync, writeFileSync } from "node:fs";
+import { join } from "node:path";
+import { runMatrix } from "./inform-matrix-run";
+
+const outDir = join(import.meta.dir, "..", "fixtures");
+const outFile = join(outDir, "inform-matrix.golden.json");
+mkdirSync(outDir, { recursive: true });
+writeFileSync(outFile, `${JSON.stringify(runMatrix(), null, 2)}\n`);
+console.log(`wrote ${outFile}`);