diff --git a/apps/gittensory-ui/src/lib/selfhost-env-reference.ts b/apps/gittensory-ui/src/lib/selfhost-env-reference.ts
index 373322c55a..4bdda329c7 100644
--- a/apps/gittensory-ui/src/lib/selfhost-env-reference.ts
+++ b/apps/gittensory-ui/src/lib/selfhost-env-reference.ts
@@ -7,23 +7,23 @@ export type SelfHostEnvReferenceRow = {
 export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   {
     name: "AI_COMBINE",
-    firstReference: "src/selfhost/ai.ts:936",
+    firstReference: "src/selfhost/ai.ts:968",
   },
   {
     name: "AI_EMBED_API_KEY",
-    firstReference: "src/server.ts:445",
+    firstReference: "src/server.ts:440",
   },
   {
     name: "AI_EMBED_BASE_URL",
-    firstReference: "src/server.ts:442",
+    firstReference: "src/server.ts:437",
   },
   {
     name: "AI_EMBED_MODEL",
-    firstReference: "src/selfhost/ai.ts:832",
+    firstReference: "src/selfhost/ai.ts:864",
   },
   {
     name: "AI_ON_MERGE",
-    firstReference: "src/selfhost/ai.ts:938",
+    firstReference: "src/selfhost/ai.ts:970",
   },
   {
     name: "AI_PROVIDER",
@@ -31,19 +31,19 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "ANTHROPIC_AI_BASE_URL",
-    firstReference: "src/selfhost/ai.ts:836",
+    firstReference: "src/selfhost/ai.ts:868",
   },
   {
     name: "ANTHROPIC_AI_MODEL",
-    firstReference: "src/selfhost/ai.ts:57",
+    firstReference: "src/selfhost/ai.ts:85",
   },
   {
     name: "ANTHROPIC_API_KEY",
-    firstReference: "src/selfhost/ai.ts:835",
+    firstReference: "src/selfhost/ai.ts:867",
   },
   {
     name: "BACKUP_ACKNOWLEDGED",
-    firstReference: "src/server.ts:384",
+    firstReference: "src/server.ts:379",
   },
   {
     name: "BROWSER_WS_ENDPOINT",
@@ -51,39 +51,39 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "CLAUDE_AI_EFFORT",
-    firstReference: "src/selfhost/ai.ts:108",
+    firstReference: "src/selfhost/ai.ts:136",
   },
   {
     name: "CLAUDE_AI_MODEL",
-    firstReference: "src/selfhost/ai.ts:49",
+    firstReference: "src/selfhost/ai.ts:77",
   },
   {
     name: "CLAUDE_AI_TIMEOUT_MS",
-    firstReference: "src/selfhost/ai.ts:108",
+    firstReference: "src/selfhost/ai.ts:136",
   },
   {
     name: "CODEX_AI_EFFORT",
-    firstReference: "src/selfhost/ai.ts:112",
+    firstReference: "src/selfhost/ai.ts:140",
   },
   {
     name: "CODEX_AI_MODEL",
-    firstReference: "src/selfhost/ai.ts:53",
+    firstReference: "src/selfhost/ai.ts:81",
   },
   {
     name: "CODEX_AI_TIMEOUT_MS",
-    firstReference: "src/selfhost/ai.ts:112",
+    firstReference: "src/selfhost/ai.ts:140",
   },
   {
     name: "CODEX_HOME",
-    firstReference: "src/selfhost/ai.ts:274",
+    firstReference: "src/selfhost/ai.ts:302",
   },
   {
     name: "CRON_INTERVAL_MS",
-    firstReference: "src/server.ts:921",
+    firstReference: "src/server.ts:916",
   },
   {
     name: "DATABASE_PATH",
-    firstReference: "src/server.ts:250",
+    firstReference: "src/server.ts:249",
   },
   {
     name: "DATABASE_URL",
@@ -111,19 +111,19 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "GITHUB_CACHE_TTL_SECONDS",
-    firstReference: "src/server.ts:513",
+    firstReference: "src/server.ts:508",
   },
   {
     name: "GITTENSORY_REPO_CONFIG_DIR",
-    firstReference: "src/server.ts:289",
+    firstReference: "src/server.ts:288",
   },
   {
     name: "GITTENSORY_VERSION",
-    firstReference: "src/selfhost/health.ts:29",
+    firstReference: "src/selfhost/otel.ts:62",
   },
   {
     name: "HOME",
-    firstReference: "src/selfhost/ai.ts:274",
+    firstReference: "src/selfhost/ai.ts:302",
   },
   {
     name: "MAINTENANCE_ADMISSION_ENABLED",
@@ -131,7 +131,7 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "MIGRATIONS_DIR",
-    firstReference: "src/server.ts:397",
+    firstReference: "src/server.ts:392",
   },
   {
     name: "OBSERVABILITY_SMOKE_POLL_MS",
@@ -143,39 +143,39 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "OLLAMA_AI_API_KEY",
-    firstReference: "src/selfhost/ai.ts:829",
+    firstReference: "src/selfhost/ai.ts:861",
   },
   {
     name: "OLLAMA_AI_BASE_URL",
-    firstReference: "src/selfhost/ai.ts:825",
+    firstReference: "src/selfhost/ai.ts:857",
   },
   {
     name: "OLLAMA_AI_MODEL",
-    firstReference: "src/selfhost/ai.ts:61",
+    firstReference: "src/selfhost/ai.ts:89",
   },
   {
     name: "OPENAI_AI_BASE_URL",
-    firstReference: "src/selfhost/ai.ts:827",
+    firstReference: "src/selfhost/ai.ts:859",
   },
   {
     name: "OPENAI_AI_MODEL",
-    firstReference: "src/selfhost/ai.ts:62",
+    firstReference: "src/selfhost/ai.ts:90",
   },
   {
     name: "OPENAI_API_KEY",
-    firstReference: "src/selfhost/ai.ts:829",
+    firstReference: "src/selfhost/ai.ts:861",
   },
   {
     name: "OPENAI_COMPATIBLE_AI_API_KEY",
-    firstReference: "src/selfhost/ai.ts:829",
+    firstReference: "src/selfhost/ai.ts:861",
   },
   {
     name: "OPENAI_COMPATIBLE_AI_BASE_URL",
-    firstReference: "src/selfhost/ai.ts:828",
+    firstReference: "src/selfhost/ai.ts:860",
   },
   {
     name: "OPENAI_COMPATIBLE_AI_MODEL",
-    firstReference: "src/selfhost/ai.ts:63",
+    firstReference: "src/selfhost/ai.ts:91",
   },
   {
     name: "ORB_AIR_GAP",
@@ -191,7 +191,7 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "ORB_BROKER_URL",
-    firstReference: "src/server.ts:970",
+    firstReference: "src/server.ts:965",
   },
   {
     name: "ORB_COLLECTOR_TOKEN",
@@ -207,7 +207,7 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "ORB_RELAY_MODE",
-    firstReference: "src/server.ts:972",
+    firstReference: "src/server.ts:967",
   },
   {
     name: "OTEL_EXPORTER_OTLP_ENDPOINT",
@@ -239,11 +239,11 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "PGVECTOR_ENABLED",
-    firstReference: "src/server.ts:230",
+    firstReference: "src/server.ts:229",
   },
   {
     name: "PORT",
-    firstReference: "src/server.ts:720",
+    firstReference: "src/server.ts:715",
   },
   {
     name: "PUBLIC_API_ORIGIN",
@@ -259,7 +259,7 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "QDRANT_URL",
-    firstReference: "src/server.ts:532",
+    firstReference: "src/server.ts:527",
   },
   {
     name: "QUEUE_BACKGROUND_CONCURRENCY",
@@ -271,7 +271,7 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "REVIEW_AUDIT_DIR",
-    firstReference: "src/server.ts:577",
+    firstReference: "src/server.ts:572",
   },
   {
     name: "SELFHOST_BUNDLE_ALL",
@@ -307,7 +307,7 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
   },
   {
     name: "SETUP_OUTPUT_PATH",
-    firstReference: "src/server.ts:837",
+    firstReference: "src/server.ts:832",
   },
   {
     name: "SLACK_WEBHOOK_URL",
@@ -318,57 +318,57 @@ export const SELFHOST_ENV_REFERENCE_ROWS: SelfHostEnvReferenceRow[] = [
 export const SELFHOST_ENV_REFERENCE_MARKDOWN = [
   "| Name | First reference |",
   "| --- | --- |",
-  "| `AI_COMBINE` | `src/selfhost/ai.ts:936` |",
-  "| `AI_EMBED_API_KEY` | `src/server.ts:445` |",
-  "| `AI_EMBED_BASE_URL` | `src/server.ts:442` |",
-  "| `AI_EMBED_MODEL` | `src/selfhost/ai.ts:832` |",
-  "| `AI_ON_MERGE` | `src/selfhost/ai.ts:938` |",
+  "| `AI_COMBINE` | `src/selfhost/ai.ts:968` |",
+  "| `AI_EMBED_API_KEY` | `src/server.ts:440` |",
+  "| `AI_EMBED_BASE_URL` | `src/server.ts:437` |",
+  "| `AI_EMBED_MODEL` | `src/selfhost/ai.ts:864` |",
+  "| `AI_ON_MERGE` | `src/selfhost/ai.ts:970` |",
   "| `AI_PROVIDER` | `src/selfhost/ai-config.ts:43` |",
-  "| `ANTHROPIC_AI_BASE_URL` | `src/selfhost/ai.ts:836` |",
-  "| `ANTHROPIC_AI_MODEL` | `src/selfhost/ai.ts:57` |",
-  "| `ANTHROPIC_API_KEY` | `src/selfhost/ai.ts:835` |",
-  "| `BACKUP_ACKNOWLEDGED` | `src/server.ts:384` |",
+  "| `ANTHROPIC_AI_BASE_URL` | `src/selfhost/ai.ts:868` |",
+  "| `ANTHROPIC_AI_MODEL` | `src/selfhost/ai.ts:85` |",
+  "| `ANTHROPIC_API_KEY` | `src/selfhost/ai.ts:867` |",
+  "| `BACKUP_ACKNOWLEDGED` | `src/server.ts:379` |",
   "| `BROWSER_WS_ENDPOINT` | `src/selfhost/stubs/puppeteer.ts:11` |",
-  "| `CLAUDE_AI_EFFORT` | `src/selfhost/ai.ts:108` |",
-  "| `CLAUDE_AI_MODEL` | `src/selfhost/ai.ts:49` |",
-  "| `CLAUDE_AI_TIMEOUT_MS` | `src/selfhost/ai.ts:108` |",
-  "| `CODEX_AI_EFFORT` | `src/selfhost/ai.ts:112` |",
-  "| `CODEX_AI_MODEL` | `src/selfhost/ai.ts:53` |",
-  "| `CODEX_AI_TIMEOUT_MS` | `src/selfhost/ai.ts:112` |",
-  "| `CODEX_HOME` | `src/selfhost/ai.ts:274` |",
-  "| `CRON_INTERVAL_MS` | `src/server.ts:921` |",
-  "| `DATABASE_PATH` | `src/server.ts:250` |",
+  "| `CLAUDE_AI_EFFORT` | `src/selfhost/ai.ts:136` |",
+  "| `CLAUDE_AI_MODEL` | `src/selfhost/ai.ts:77` |",
+  "| `CLAUDE_AI_TIMEOUT_MS` | `src/selfhost/ai.ts:136` |",
+  "| `CODEX_AI_EFFORT` | `src/selfhost/ai.ts:140` |",
+  "| `CODEX_AI_MODEL` | `src/selfhost/ai.ts:81` |",
+  "| `CODEX_AI_TIMEOUT_MS` | `src/selfhost/ai.ts:140` |",
+  "| `CODEX_HOME` | `src/selfhost/ai.ts:302` |",
+  "| `CRON_INTERVAL_MS` | `src/server.ts:916` |",
+  "| `DATABASE_PATH` | `src/server.ts:249` |",
   "| `DATABASE_URL` | `src/selfhost/preflight.ts:201` |",
   "| `DISCORD_REPO_WEBHOOKS` | `src/services/notify-discord.ts:41` |",
   "| `DISCORD_WEBHOOK_URL` | `src/services/notify-discord.ts:78` |",
   "| `FOREGROUND_LIVENESS_ENABLED` | `src/selfhost/foreground-liveness.ts:41` |",
   "| `GITHUB_APP_ID` | `src/selfhost/orb-collector.ts:59` |",
   "| `GITHUB_APP_PRIVATE_KEY` | `src/selfhost/orb-collector.ts:166` |",
-  "| `GITHUB_CACHE_TTL_SECONDS` | `src/server.ts:513` |",
-  "| `GITTENSORY_REPO_CONFIG_DIR` | `src/server.ts:289` |",
-  "| `GITTENSORY_VERSION` | `src/selfhost/health.ts:29` |",
-  "| `HOME` | `src/selfhost/ai.ts:274` |",
+  "| `GITHUB_CACHE_TTL_SECONDS` | `src/server.ts:508` |",
+  "| `GITTENSORY_REPO_CONFIG_DIR` | `src/server.ts:288` |",
+  "| `GITTENSORY_VERSION` | `src/selfhost/otel.ts:62` |",
+  "| `HOME` | `src/selfhost/ai.ts:302` |",
   "| `MAINTENANCE_ADMISSION_ENABLED` | `src/selfhost/maintenance-admission.ts:126` |",
-  "| `MIGRATIONS_DIR` | `src/server.ts:397` |",
+  "| `MIGRATIONS_DIR` | `src/server.ts:392` |",
   "| `OBSERVABILITY_SMOKE_POLL_MS` | `scripts/smoke-observability-traces.mjs:8` |",
   "| `OBSERVABILITY_SMOKE_TIMEOUT_MS` | `scripts/smoke-observability-traces.mjs:6` |",
-  "| `OLLAMA_AI_API_KEY` | `src/selfhost/ai.ts:829` |",
-  "| `OLLAMA_AI_BASE_URL` | `src/selfhost/ai.ts:825` |",
-  "| `OLLAMA_AI_MODEL` | `src/selfhost/ai.ts:61` |",
-  "| `OPENAI_AI_BASE_URL` | `src/selfhost/ai.ts:827` |",
-  "| `OPENAI_AI_MODEL` | `src/selfhost/ai.ts:62` |",
-  "| `OPENAI_API_KEY` | `src/selfhost/ai.ts:829` |",
-  "| `OPENAI_COMPATIBLE_AI_API_KEY` | `src/selfhost/ai.ts:829` |",
-  "| `OPENAI_COMPATIBLE_AI_BASE_URL` | `src/selfhost/ai.ts:828` |",
-  "| `OPENAI_COMPATIBLE_AI_MODEL` | `src/selfhost/ai.ts:63` |",
+  "| `OLLAMA_AI_API_KEY` | `src/selfhost/ai.ts:861` |",
+  "| `OLLAMA_AI_BASE_URL` | `src/selfhost/ai.ts:857` |",
+  "| `OLLAMA_AI_MODEL` | `src/selfhost/ai.ts:89` |",
+  "| `OPENAI_AI_BASE_URL` | `src/selfhost/ai.ts:859` |",
+  "| `OPENAI_AI_MODEL` | `src/selfhost/ai.ts:90` |",
+  "| `OPENAI_API_KEY` | `src/selfhost/ai.ts:861` |",
+  "| `OPENAI_COMPATIBLE_AI_API_KEY` | `src/selfhost/ai.ts:861` |",
+  "| `OPENAI_COMPATIBLE_AI_BASE_URL` | `src/selfhost/ai.ts:860` |",
+  "| `OPENAI_COMPATIBLE_AI_MODEL` | `src/selfhost/ai.ts:91` |",
   "| `ORB_AIR_GAP` | `src/selfhost/orb-collector.ts:161` |",
   "| `ORB_ANONYMIZE` | `src/selfhost/orb-collector.ts:174` |",
   "| `ORB_APP_ID` | `src/selfhost/orb-collector.ts:59` |",
-  "| `ORB_BROKER_URL` | `src/server.ts:970` |",
+  "| `ORB_BROKER_URL` | `src/server.ts:965` |",
   "| `ORB_COLLECTOR_TOKEN` | `src/selfhost/orb-collector.ts:205` |",
   "| `ORB_COLLECTOR_URL` | `src/selfhost/orb-collector.ts:172` |",
   "| `ORB_ENROLLMENT_SECRET` | `src/selfhost/orb-collector.ts:165` |",
-  "| `ORB_RELAY_MODE` | `src/server.ts:972` |",
+  "| `ORB_RELAY_MODE` | `src/server.ts:967` |",
   "| `OTEL_EXPORTER_OTLP_ENDPOINT` | `src/selfhost/otel.ts:47` |",
   "| `OTEL_EXPORTER_OTLP_TRACES_ENDPOINT` | `src/selfhost/otel.ts:45` |",
   "| `OTEL_SERVICE_ENVIRONMENT` | `src/selfhost/otel.ts:60` |",
@@ -376,15 +376,15 @@ export const SELFHOST_ENV_REFERENCE_MARKDOWN = [
   "| `OTEL_TRACES_EXPORTER` | `src/selfhost/otel.ts:40` |",
   "| `OTEL_TRACES_SAMPLER` | `src/selfhost/otel.ts:74` |",
   "| `OTEL_TRACES_SAMPLER_ARG` | `src/selfhost/otel.ts:76` |",
-  "| `PGVECTOR_ENABLED` | `src/server.ts:230` |",
-  "| `PORT` | `src/server.ts:720` |",
+  "| `PGVECTOR_ENABLED` | `src/server.ts:229` |",
+  "| `PORT` | `src/server.ts:715` |",
   "| `PUBLIC_API_ORIGIN` | `src/selfhost/preflight.ts:192` |",
   "| `QDRANT_API_KEY` | `src/selfhost/qdrant-vectorize.ts:50` |",
   "| `QDRANT_DIM` | `src/selfhost/qdrant-vectorize.ts:71` |",
-  "| `QDRANT_URL` | `src/server.ts:532` |",
+  "| `QDRANT_URL` | `src/server.ts:527` |",
   "| `QUEUE_BACKGROUND_CONCURRENCY` | `src/selfhost/queue-common.ts:120` |",
   "| `REDIS_URL` | `src/selfhost/preflight.ts:144` |",
-  "| `REVIEW_AUDIT_DIR` | `src/server.ts:577` |",
+  "| `REVIEW_AUDIT_DIR` | `src/server.ts:572` |",
   "| `SELFHOST_BUNDLE_ALL` | `scripts/build-selfhost.mjs:13` |",
   "| `SELFHOST_SERVICE` | `scripts/smoke-observability-traces.mjs:5` |",
   "| `SELFHOST_SETUP_TOKEN` | `src/selfhost/preflight.ts:186` |",
@@ -393,6 +393,6 @@ export const SELFHOST_ENV_REFERENCE_MARKDOWN = [
   "| `SENTRY_RELEASE` | `src/selfhost/otel.ts:62` |",
   "| `SENTRY_SERVER_NAME` | `src/selfhost/sentry.ts:383` |",
   "| `SENTRY_TRACES_SAMPLE_RATE` | `src/selfhost/sentry.ts:171` |",
-  "| `SETUP_OUTPUT_PATH` | `src/server.ts:837` |",
+  "| `SETUP_OUTPUT_PATH` | `src/server.ts:832` |",
   "| `SLACK_WEBHOOK_URL` | `src/services/notify-discord.ts:173` |",
 ].join("\n");
diff --git a/src/selfhost/ai.ts b/src/selfhost/ai.ts
index 7da290ebb9..9bf5844e54 100644
--- a/src/selfhost/ai.ts
+++ b/src/selfhost/ai.ts
@@ -16,6 +16,7 @@ import { delimiter } from "node:path";
 interface AiRunOptions {
   messages?: Array<{ role: string; content: string }>;
   prompt?: string;
+  systemAppend?: string;
   text?: string[]; // embedding input — the core's embedTexts passes { text: string[] }
   max_tokens?: number;
   temperature?: number;
@@ -32,6 +33,33 @@ function toMessages(options: AiRunOptions): Array<{ role: string; content: strin
   return [{ role: "user", content: String(options.prompt ?? "") }];
 }
 
+function normalizedSystemAppend(options: AiRunOptions): string | undefined {
+  const trimmed = options.systemAppend?.trim();
+  return trimmed ? trimmed : undefined;
+}
+
+function stripSystemAppend(content: string, systemAppend: string): string {
+  const index = content.indexOf(systemAppend);
+  if (index < 0) return content;
+  return `${content.slice(0, index)}${content.slice(index + systemAppend.length)}`.trimEnd();
+}
+
+function toCliPrompt(options: AiRunOptions, systemAppend: string | undefined): string {
+  return toMessages(options)
+    .map((message) =>
+      systemAppend && message.role === "system"
+        ? stripSystemAppend(message.content, systemAppend)
+        : message.content,
+    )
+    .join("\n\n");
+}
+
+function prependCodexSystemAppend(prompt: string, systemAppend: string | undefined): string {
+  return systemAppend
+    ? `ADDITIONAL SYSTEM INSTRUCTIONS:\n${systemAppend}\n\n${prompt}`
+    : prompt;
+}
+
 /** The core passes a Workers-AI model id (e.g. "@cf/meta/llama-3.1-8b-instruct-fp8-fast") that is meaningless
  *  off-Workers — handing it to Ollama or `claude --model` fails. Prefer the provider-specific self-host model,
  *  then any non-Workers model the core passed, then a provider default. */
@@ -565,12 +593,15 @@ export function createClaudeCodeAi(parentEnv: Record<string, string | undefined>
       try {
         if (!token) throw new Error("claude_code_no_oauth_token");
         const env = subscriptionCliEnv(parentEnv, { CLAUDE_CODE_OAUTH_TOKEN: token });
-        const prompt = toMessages(options).map((m) => m.content).join("\n\n");
+        const systemAppend = normalizedSystemAppend(options);
+        const prompt = toCliPrompt(options, systemAppend);
         const spawn = spawnImpl ?? (await defaultSpawn());
+        const args = ["--print", "--output-format", "json", "--model", claudeModel, "--permission-mode", "plan", "--effort", effort, "--disallowedTools", "Bash,Edit,Write,WebFetch,WebSearch"];
+        if (systemAppend) args.push("--append-system-prompt", systemAppend);
         attempted = true;
         const { stdout, code, stderr, timedOut } = await spawn(
           "claude",
-          ["--print", "--output-format", "json", "--model", claudeModel, "--permission-mode", "plan", "--effort", effort, "--disallowedTools", "Bash,Edit,Write,WebFetch,WebSearch"],
+          args,
           { env, input: prompt, timeoutMs, cwd: await isolatedCliCwd() },
         );
         stdoutForMetrics = stdout;
@@ -619,7 +650,8 @@ export function createCodexAi(
         assertCodexCredentialIsolation(parentEnv);
         await authCheckImpl(parentEnv);
         const env = codexCliEnv(parentEnv);
-        const prompt = toMessages(options).map((m) => m.content).join("\n\n");
+        const systemAppend = normalizedSystemAppend(options);
+        const prompt = prependCodexSystemAppend(toCliPrompt(options, systemAppend), systemAppend);
         const spawn = spawnImpl ?? (await defaultSpawn());
         const args = ["exec", "--json", "--skip-git-repo-check", "--sandbox", "read-only"];
         if (codexModel) args.push("--model", codexModel);
diff --git a/src/services/ai-review.ts b/src/services/ai-review.ts
index e541267b98..9e1d1a9c8c 100644
--- a/src/services/ai-review.ts
+++ b/src/services/ai-review.ts
@@ -355,6 +355,13 @@ type AiRunner = {
   ) => Promise<unknown>;
 };
 
+function selfHostCliSystemAppend(model: string, systemAppend: string): string | undefined {
+  const trimmed = systemAppend.trim();
+  if (!trimmed) return undefined;
+  const [provider = ""] = model.trim().toLowerCase().split(":");
+  return provider === "claude-code" || provider === "codex" ? trimmed : undefined;
+}
+
 // Exported so the sibling AI-advisory features (e.g. the slop advisory in `./ai-slop`) share ONE budget
 // window + neuron estimator and never drift from the review path's accounting.
 export function isEnabled(value: string | undefined): boolean {
@@ -648,13 +655,19 @@ function buildSystemPrompt(input: GittensoryAiReviewInput): string {
   const pathSuffix = input.pathGuidance?.trim() ? input.pathGuidance : "";
   // `.gittensory.yml` review.instructions (#review-instructions): a repo-level maintainer brief appended to every
   // review; empty ⇒ nothing appended (byte-identical).
-  const repoInstructionsSuffix = input.repoInstructions?.trim()
-    ? ` REPOSITORY REVIEW INSTRUCTIONS (maintainer conventions for this repo — honor them unless they conflict with a real defect): ${input.repoInstructions.trim()}`
-    : "";
+  const repoInstructionsAppend = buildRepoInstructionsSystemAppend(input.repoInstructions);
+  const repoInstructionsSuffix = repoInstructionsAppend ? ` ${repoInstructionsAppend}` : "";
   const inlineSuffix = input.inlineFindings ? INLINE_FINDINGS_SUFFIX : "";
   return `${REVIEW_SYSTEM_PROMPT}${groundingSuffix}${enrichmentSuffix}${profileSuffix}${securityFocusSuffix}${pathSuffix}${repoInstructionsSuffix}${inlineSuffix}`;
 }
 
+function buildRepoInstructionsSystemAppend(repoInstructions: string | null | undefined): string {
+  const trimmed = repoInstructions?.trim();
+  return trimmed
+    ? `REPOSITORY REVIEW INSTRUCTIONS (maintainer conventions for this repo — honor them unless they conflict with a real defect): ${trimmed}`
+    : "";
+}
+
 /** One Workers-AI opinion with a per-slot reliable fallback and a 3× retry on the primary. */
 async function runWorkersOpinion(
   env: Env,
@@ -664,6 +677,7 @@ async function runWorkersOpinion(
   user: string,
   maxTokens: number,
   diagnostics: AiReviewDiagnostic[] = [],
+  systemAppend = "",
 ): Promise<ReviewerOpinionOutcome> {
   const ai = env.AI as unknown as AiRunner | undefined;
   if (!ai || typeof ai.run !== "function") return { review: null };
@@ -685,6 +699,7 @@ async function runWorkersOpinion(
     : [primary]) {
     for (let attempt = 0; attempt < 3; attempt += 1) {
       try {
+        const cliSystemAppend = selfHostCliSystemAppend(model, systemAppend);
         const result = await ai.run(
           model,
           {
@@ -694,6 +709,7 @@ async function runWorkersOpinion(
               { role: "system", content: system },
               { role: "user", content: user },
             ],
+            ...(cliSystemAppend ? { systemAppend: cliSystemAppend } : {}),
           },
           extra,
         );
@@ -1162,6 +1178,7 @@ export async function runGittensoryAiReview(
   // reviewers are told to verify claims against the attached CI/files; otherwise this is REVIEW_SYSTEM_PROMPT
   // unchanged (byte-identical). Computed from `promptInput` so it travels with the (possibly defanged) input.
   const system = buildSystemPrompt(promptInput);
+  const repoInstructionsSystemAppend = buildRepoInstructionsSystemAppend(promptInput.repoInstructions);
   // The daily neuron budget governs FREE Workers-AI spend only. BYOK advisory calls bill the maintainer's
   // own provider account, so they are not counted here (and a BYOK advisory still runs when the free
   // budget is exhausted). Free calls = the consensus pair in block mode (always Workers AI), plus the
@@ -1286,6 +1303,7 @@ export async function runGittensoryAiReview(
       user,
       maxTokens,
       reviewDiagnostics,
+      repoInstructionsSystemAppend,
     );
     advisoryReview = outcome.review;
     if (outcome.fallbackNote) fallbackNotes.push(outcome.fallbackNote);
@@ -1311,6 +1329,7 @@ export async function runGittensoryAiReview(
               user,
               maxTokens,
               reviewDiagnostics,
+              repoInstructionsSystemAppend,
             )
           : Promise.resolve<ReviewerOpinionOutcome>({ review: advisoryReview }),
         runWorkersOpinion(
@@ -1321,6 +1340,7 @@ export async function runGittensoryAiReview(
           user,
           maxTokens,
           reviewDiagnostics,
+          repoInstructionsSystemAppend,
         ),
       ]);
       if (a.fallbackNote) fallbackNotes.push(a.fallbackNote);
@@ -1345,6 +1365,7 @@ export async function runGittensoryAiReview(
             user,
             maxTokens,
             reviewDiagnostics,
+            repoInstructionsSystemAppend,
           )
         : ({ review: advisoryReview } as ReviewerOpinionOutcome);
       if (a.fallbackNote) fallbackNotes.push(a.fallbackNote);
diff --git a/test/unit/ai-review.test.ts b/test/unit/ai-review.test.ts
index f181c2f053..628ac3d476 100644
--- a/test/unit/ai-review.test.ts
+++ b/test/unit/ai-review.test.ts
@@ -341,9 +341,12 @@ describe("review.profile shapes the reviewer system prompt (#review-profile)", (
   });
 
   it("repoInstructions (#review-instructions) is appended to the system prompt; absent leaves it byte-identical", async () => {
+    const optionsOf = (run: ReturnType<typeof vi.fn>): { messages?: Array<{ content?: string }>; systemAppend?: string } => {
+      const calls = run.mock.calls as unknown as Array<[unknown, { messages?: Array<{ content?: string }>; systemAppend?: string }]>;
+      return calls[0]?.[1] ?? {};
+    };
     const systemPromptOf = (run: ReturnType<typeof vi.fn>): string =>
-      (run.mock.calls[0]?.[1] as { messages?: Array<{ content?: string }> })
-        ?.messages?.[0]?.content ?? "";
+      optionsOf(run).messages?.[0]?.content ?? "";
     const runInstr = async (repoInstructions: string | undefined) => {
       const run = vi.fn(async () => ({ response: reviewJson() }));
       const env = createTestEnv({
@@ -353,20 +356,50 @@ describe("review.profile shapes the reviewer system prompt (#review-profile)", (
         AI_DAILY_NEURON_BUDGET: "100000",
       });
       await runGittensoryAiReview(env, { ...baseInput, repoInstructions });
-      return systemPromptOf(run);
+      return { system: systemPromptOf(run), options: optionsOf(run) };
     };
     const withInstr = await runInstr("Follow our async-error conventions.");
-    expect(withInstr).toContain("REPOSITORY REVIEW INSTRUCTIONS");
-    expect(withInstr).toContain("async-error conventions");
+    expect(withInstr.system).toContain("REPOSITORY REVIEW INSTRUCTIONS");
+    expect(withInstr.system).toContain("async-error conventions");
+    expect(withInstr.options.systemAppend).toBeUndefined();
     // Absent or whitespace-only → no append (byte-identical prompt).
-    expect(await runInstr(undefined)).not.toContain(
+    expect((await runInstr(undefined)).system).not.toContain(
       "REPOSITORY REVIEW INSTRUCTIONS",
     );
-    expect(await runInstr("   ")).not.toContain(
+    expect((await runInstr("   ")).system).not.toContain(
       "REPOSITORY REVIEW INSTRUCTIONS",
     );
   });
 
+  it("repoInstructions are passed as systemAppend only for self-host CLI reviewers (#1471)", async () => {
+    const optionsFor = async (model: string, repoInstructions: string | undefined) => {
+      const run = vi.fn(async () => ({ response: reviewJson() }));
+      const env = createTestEnv({
+        AI: { run } as unknown as Ai,
+        AI_SUMMARIES_ENABLED: "true",
+        AI_PUBLIC_COMMENTS_ENABLED: "true",
+        AI_DAILY_NEURON_BUDGET: "100000",
+      });
+      await runGittensoryAiReview(env, {
+        ...baseInput,
+        reviewers: [{ model }],
+        combine: "single",
+        repoInstructions,
+      });
+      const calls = run.mock.calls as unknown as Array<[unknown, { messages?: Array<{ content?: string }>; systemAppend?: string }]>;
+      return calls[0]?.[1] ?? {};
+    };
+
+    for (const model of ["claude-code", "codex"]) {
+      const options = await optionsFor(model, "Follow our async-error conventions.");
+      expect(options.systemAppend).toContain("REPOSITORY REVIEW INSTRUCTIONS");
+      expect(options.systemAppend).toContain("async-error conventions");
+      expect(options.messages?.[0]?.content).toContain(options.systemAppend);
+    }
+    expect((await optionsFor("claude-code", undefined)).systemAppend).toBeUndefined();
+    expect((await optionsFor("claude-code", "   ")).systemAppend).toBeUndefined();
+  });
+
   it("the inline-findings instruction is appended to the system prompt ONLY when requested (#inline-comments)", async () => {
     const systemPromptOf = (run: ReturnType<typeof vi.fn>): string =>
       (run.mock.calls[0]?.[1] as { messages?: Array<{ content?: string }> })
diff --git a/test/unit/selfhost-ai.test.ts b/test/unit/selfhost-ai.test.ts
index bade34b448..dd6a3d888b 100644
--- a/test/unit/selfhost-ai.test.ts
+++ b/test/unit/selfhost-ai.test.ts
@@ -80,6 +80,10 @@ type StubSpawn = (
 // the preflight itself (resolveCodexAuthPath / assertCodexAuthConfigured) is covered separately below.
 const noAuthCheck = async () => undefined;
 
+function countOccurrences(haystack: string | undefined, needle: string): number {
+  return haystack?.split(needle).length ? haystack.split(needle).length - 1 : 0;
+}
+
 describe("createOpenAiCompatibleAi (#979)", () => {
   it("POSTs to /chat/completions and returns { response }", async () => {
     const calls: Array<{ url: string; body: { model: string } }> = [];
@@ -717,6 +721,7 @@ describe("subscription CLI helpers + fail-safe", () => {
     await createClaudeCodeAi({ CLAUDE_CODE_OAUTH_TOKEN: "t" }, cap).run("", { prompt: "x" });
     expect(seen[seen.indexOf("--model") + 1]).toBe("claude-sonnet-4-6");
     expect(seen[seen.indexOf("--effort") + 1]).toBe("high");
+    expect(seen).not.toContain("--append-system-prompt");
     expect(timeout).toBe(240_000); // high → 240s (not the old fixed 120s)
     // Provider-specific overrides flow through to the argv + timeout scale.
     await createClaudeCodeAi({ CLAUDE_CODE_OAUTH_TOKEN: "t", CLAUDE_AI_MODEL: "claude-opus-4-8", CLAUDE_AI_EFFORT: "max" }, cap).run("", { prompt: "x" });
@@ -725,6 +730,35 @@ describe("subscription CLI helpers + fail-safe", () => {
     expect(timeout).toBe(600_000); // max → 600s, so a large max-effort review isn't SIGKILLed at 120s
   });
 
+  it("Claude Code passes systemAppend through --append-system-prompt and strips the duplicate stdin copy (#1471)", async () => {
+    const systemAppend = "REPOSITORY REVIEW INSTRUCTIONS: Follow async-error conventions.";
+    let seen: string[] = [];
+    let capturedInput = "";
+    const cap: StubSpawn = async (_c, a, o) => {
+      seen = a;
+      capturedInput = o.input ?? "";
+      return { stdout: JSON.stringify({ type: "result", result: "ok" }), code: 0 };
+    };
+    await createClaudeCodeAi({ CLAUDE_CODE_OAUTH_TOKEN: "t" }, cap).run("", {
+      messages: [
+        { role: "system", content: `Base system. ${systemAppend}` },
+        { role: "user", content: "Review this diff." },
+      ],
+      systemAppend,
+    });
+    expect(seen[seen.indexOf("--append-system-prompt") + 1]).toBe(systemAppend);
+    expect(capturedInput).toContain("Base system.");
+    expect(capturedInput).toContain("Review this diff.");
+    expect(capturedInput).not.toContain(systemAppend);
+
+    await createClaudeCodeAi({ CLAUDE_CODE_OAUTH_TOKEN: "t" }, cap).run("", {
+      prompt: "Review this diff.",
+      systemAppend: "   ",
+    });
+    expect(seen).not.toContain("--append-system-prompt");
+    expect(capturedInput).toBe("Review this diff.");
+  });
+
   it("chat-only CLIs reject embeds so the chain routes embeddings to an embed-capable provider (Claude review + ollama embed)", async () => {
     const reviewOk: StubSpawn = async () => ({ stdout: JSON.stringify({ type: "result", result: "the review" }), code: 0 });
     // A stand-in embed-capable provider (e.g. ollama): returns `data` for an embed request, `response` for chat.
@@ -776,6 +810,36 @@ describe("subscription CLI helpers + fail-safe", () => {
     await expect(createCodexAi({ GITTENSORY_ENABLE_UNSAFE_CODEX_REVIEWER: "1" }, bad, noAuthCheck).run("", { prompt: "x" })).rejects.toThrow(/codex_exit_1/);
   });
 
+  it("Codex prepends systemAppend to stdin once and strips an existing system copy (#1471)", async () => {
+    const systemAppend = "REPOSITORY REVIEW INSTRUCTIONS: Follow async-error conventions.";
+    let capturedInput = "";
+    const ok: StubSpawn = async (_cmd, _args, opts) => {
+      capturedInput = opts.input ?? "";
+      return { stdout: JSON.stringify({ type: "result", result: "codex review" }), code: 0 };
+    };
+    await createCodexAi({ GITTENSORY_ENABLE_UNSAFE_CODEX_REVIEWER: "1" }, ok, noAuthCheck).run("", {
+      messages: [
+        { role: "system", content: `Base system. ${systemAppend}` },
+        { role: "user", content: "Review this diff." },
+      ],
+      systemAppend,
+    });
+    expect(capturedInput.startsWith("ADDITIONAL SYSTEM INSTRUCTIONS:\n")).toBe(true);
+    expect(countOccurrences(capturedInput, systemAppend)).toBe(1);
+    expect(capturedInput).toContain("Base system.");
+    expect(capturedInput).toContain("Review this diff.");
+
+    await createCodexAi({ GITTENSORY_ENABLE_UNSAFE_CODEX_REVIEWER: "1" }, ok, noAuthCheck).run("", {
+      messages: [
+        { role: "system", content: "Base system without the append block." },
+        { role: "user", content: "Review this diff." },
+      ],
+      systemAppend,
+    });
+    expect(countOccurrences(capturedInput, systemAppend)).toBe(1);
+    expect(capturedInput).toContain("Base system without the append block.");
+  });
+
   it("drives the REAL subprocess (defaultSpawn) against a fake `claude` on PATH", async () => {
     const dir = mkdtempSync(join(tmpdir(), "fakecli-"));
     const fake = join(dir, "claude");