diff --git a/docs/concepts/system-prompt.md b/docs/concepts/system-prompt.md
index b46f11578..1a52fc501 100644
--- a/docs/concepts/system-prompt.md
+++ b/docs/concepts/system-prompt.md
@@ -24,7 +24,7 @@ The prompt is intentionally compact and uses fixed sections:
 - **Current Date & Time**: user-local time, timezone, and time format.
 - **Reply Tags**: optional reply tag syntax for supported providers.
 - **Heartbeats**: heartbeat prompt and ack behavior.
-- **Runtime**: host, OS, node, model, thinking level (one line).
+- **Runtime**: host, OS, node, model, repo root (when detected), thinking level (one line).
 - **Reasoning**: current visibility level + /reasoning toggle hint.
 
 ## Prompt modes
diff --git a/docs/gateway/configuration.md b/docs/gateway/configuration.md
index 6cdc39394..1665fdcc8 100644
--- a/docs/gateway/configuration.md
+++ b/docs/gateway/configuration.md
@@ -1266,6 +1266,18 @@ Default: `~/clawd`.
 If `agents.defaults.sandbox` is enabled, non-main sessions can override this with their
 own per-scope workspaces under `agents.defaults.sandbox.workspaceRoot`.
 
+### `agents.defaults.repoRoot`
+
+Optional repository root to show in the system prompt’s Runtime line. If unset, Clawdbot
+tries to detect a `.git` directory by walking upward from the workspace (and current
+working directory). The path must exist to be used.
+
+```json5
+{
+  agents: { defaults: { repoRoot: "~/Projects/clawdbot" } }
+}
+```
+
 ### `agents.defaults.skipBootstrap`
 
 Disables automatic creation of the workspace bootstrap files (`AGENTS.md`, `SOUL.md`, `TOOLS.md`, `IDENTITY.md`, `USER.md`, and `BOOTSTRAP.md`).
diff --git a/src/agents/cli-runner/helpers.ts b/src/agents/cli-runner/helpers.ts
index c1d96ea71..26ee43495 100644
--- a/src/agents/cli-runner/helpers.ts
+++ b/src/agents/cli-runner/helpers.ts
@@ -183,6 +183,8 @@ export function buildSystemPrompt(params: {
   const { runtimeInfo, userTimezone, userTime, userTimeFormat } = buildSystemPromptParams({
     config: params.config,
     agentId: params.agentId,
+    workspaceDir: params.workspaceDir,
+    cwd: process.cwd(),
     runtime: {
       host: "clawdbot",
       os: `${os.type()} ${os.release()}`,
diff --git a/src/agents/pi-embedded-runner/run/attempt.ts b/src/agents/pi-embedded-runner/run/attempt.ts
index 19450226c..f16a71759 100644
--- a/src/agents/pi-embedded-runner/run/attempt.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.ts
@@ -279,6 +279,8 @@ export async function runEmbeddedAttempt(
     const { runtimeInfo, userTimezone, userTime, userTimeFormat } = buildSystemPromptParams({
       config: params.config,
       agentId: sessionAgentId,
+      workspaceDir: effectiveWorkspace,
+      cwd: process.cwd(),
       runtime: {
         host: machineName,
         os: `${os.type()} ${os.release()}`,
diff --git a/src/agents/system-prompt-params.test.ts b/src/agents/system-prompt-params.test.ts
new file mode 100644
index 000000000..fd108a3c7
--- /dev/null
+++ b/src/agents/system-prompt-params.test.ts
@@ -0,0 +1,106 @@
+import fs from "node:fs/promises";
+import os from "node:os";
+import path from "node:path";
+
+import { describe, expect, it } from "vitest";
+
+import type { ClawdbotConfig } from "../config/config.js";
+import { buildSystemPromptParams } from "./system-prompt-params.js";
+
+async function makeTempDir(label: string): Promise<string> {
+  return fs.mkdtemp(path.join(os.tmpdir(), `clawdbot-${label}-`));
+}
+
+async function makeRepoRoot(root: string): Promise<void> {
+  await fs.mkdir(path.join(root, ".git"), { recursive: true });
+}
+
+function buildParams(params: { config?: ClawdbotConfig; workspaceDir?: string; cwd?: string }) {
+  return buildSystemPromptParams({
+    config: params.config,
+    workspaceDir: params.workspaceDir,
+    cwd: params.cwd,
+    runtime: {
+      host: "host",
+      os: "os",
+      arch: "arch",
+      node: "node",
+      model: "model",
+    },
+  });
+}
+
+describe("buildSystemPromptParams repo root", () => {
+  it("detects repo root from workspaceDir", async () => {
+    const temp = await makeTempDir("workspace");
+    const repoRoot = path.join(temp, "repo");
+    const workspaceDir = path.join(repoRoot, "nested", "workspace");
+    await fs.mkdir(workspaceDir, { recursive: true });
+    await makeRepoRoot(repoRoot);
+
+    const { runtimeInfo } = buildParams({ workspaceDir });
+
+    expect(runtimeInfo.repoRoot).toBe(repoRoot);
+  });
+
+  it("falls back to cwd when workspaceDir has no repo", async () => {
+    const temp = await makeTempDir("cwd");
+    const repoRoot = path.join(temp, "repo");
+    const workspaceDir = path.join(temp, "workspace");
+    await fs.mkdir(workspaceDir, { recursive: true });
+    await makeRepoRoot(repoRoot);
+
+    const { runtimeInfo } = buildParams({ workspaceDir, cwd: repoRoot });
+
+    expect(runtimeInfo.repoRoot).toBe(repoRoot);
+  });
+
+  it("uses configured repoRoot when valid", async () => {
+    const temp = await makeTempDir("config");
+    const repoRoot = path.join(temp, "config-root");
+    const workspaceDir = path.join(temp, "workspace");
+    await fs.mkdir(repoRoot, { recursive: true });
+    await fs.mkdir(workspaceDir, { recursive: true });
+    await makeRepoRoot(workspaceDir);
+
+    const config: ClawdbotConfig = {
+      agents: {
+        defaults: {
+          repoRoot,
+        },
+      },
+    };
+
+    const { runtimeInfo } = buildParams({ config, workspaceDir });
+
+    expect(runtimeInfo.repoRoot).toBe(repoRoot);
+  });
+
+  it("ignores invalid repoRoot config and auto-detects", async () => {
+    const temp = await makeTempDir("invalid");
+    const repoRoot = path.join(temp, "repo");
+    const workspaceDir = path.join(repoRoot, "workspace");
+    await fs.mkdir(workspaceDir, { recursive: true });
+    await makeRepoRoot(repoRoot);
+
+    const config: ClawdbotConfig = {
+      agents: {
+        defaults: {
+          repoRoot: path.join(temp, "missing"),
+        },
+      },
+    };
+
+    const { runtimeInfo } = buildParams({ config, workspaceDir });
+
+    expect(runtimeInfo.repoRoot).toBe(repoRoot);
+  });
+
+  it("returns undefined when no repo is found", async () => {
+    const workspaceDir = await makeTempDir("norepo");
+
+    const { runtimeInfo } = buildParams({ workspaceDir });
+
+    expect(runtimeInfo.repoRoot).toBeUndefined();
+  });
+});
diff --git a/src/agents/system-prompt-params.ts b/src/agents/system-prompt-params.ts
index 21a97831a..9de8f481a 100644
--- a/src/agents/system-prompt-params.ts
+++ b/src/agents/system-prompt-params.ts
@@ -1,3 +1,6 @@
+import fs from "node:fs";
+import path from "node:path";
+
 import type { ClawdbotConfig } from "../config/config.js";
 import {
   formatUserTime,
@@ -18,6 +21,7 @@ export type RuntimeInfoInput = {
   capabilities?: string[];
   /** Supported message actions for the current channel (e.g., react, edit, unsend) */
   channelActions?: string[];
+  repoRoot?: string;
 };
 
 export type SystemPromptRuntimeParams = {
@@ -31,7 +35,14 @@ export function buildSystemPromptParams(params: {
   config?: ClawdbotConfig;
   agentId?: string;
   runtime: Omit<RuntimeInfoInput, "agentId">;
+  workspaceDir?: string;
+  cwd?: string;
 }): SystemPromptRuntimeParams {
+  const repoRoot = resolveRepoRoot({
+    config: params.config,
+    workspaceDir: params.workspaceDir,
+    cwd: params.cwd,
+  });
   const userTimezone = resolveUserTimezone(params.config?.agents?.defaults?.userTimezone);
   const userTimeFormat = resolveUserTimeFormat(params.config?.agents?.defaults?.timeFormat);
   const userTime = formatUserTime(new Date(), userTimezone, userTimeFormat);
@@ -39,9 +50,56 @@ export function buildSystemPromptParams(params: {
     runtimeInfo: {
       agentId: params.agentId,
       ...params.runtime,
+      repoRoot,
     },
     userTimezone,
     userTime,
     userTimeFormat,
   };
 }
+
+function resolveRepoRoot(params: {
+  config?: ClawdbotConfig;
+  workspaceDir?: string;
+  cwd?: string;
+}): string | undefined {
+  const configured = params.config?.agents?.defaults?.repoRoot?.trim();
+  if (configured) {
+    try {
+      const resolved = path.resolve(configured);
+      const stat = fs.statSync(resolved);
+      if (stat.isDirectory()) return resolved;
+    } catch {
+      // ignore invalid config path
+    }
+  }
+  const candidates = [params.workspaceDir, params.cwd]
+    .map((value) => value?.trim())
+    .filter(Boolean) as string[];
+  const seen = new Set<string>();
+  for (const candidate of candidates) {
+    const resolved = path.resolve(candidate);
+    if (seen.has(resolved)) continue;
+    seen.add(resolved);
+    const root = findGitRoot(resolved);
+    if (root) return root;
+  }
+  return undefined;
+}
+
+function findGitRoot(startDir: string): string | null {
+  let current = path.resolve(startDir);
+  for (let i = 0; i < 12; i += 1) {
+    const gitPath = path.join(current, ".git");
+    try {
+      const stat = fs.statSync(gitPath);
+      if (stat.isDirectory() || stat.isFile()) return current;
+    } catch {
+      // ignore missing .git at this level
+    }
+    const parent = path.dirname(current);
+    if (parent === current) break;
+    current = parent;
+  }
+  return null;
+}
diff --git a/src/agents/system-prompt.test.ts b/src/agents/system-prompt.test.ts
index fce27677a..2f0e936e4 100644
--- a/src/agents/system-prompt.test.ts
+++ b/src/agents/system-prompt.test.ts
@@ -284,6 +284,7 @@ describe("buildAgentSystemPrompt", () => {
       {
         agentId: "work",
         host: "host",
+        repoRoot: "/repo",
         os: "macOS",
         arch: "arm64",
         node: "v20",
@@ -297,6 +298,7 @@ describe("buildAgentSystemPrompt", () => {
 
     expect(line).toContain("agent=work");
     expect(line).toContain("host=host");
+    expect(line).toContain("repo=/repo");
     expect(line).toContain("os=macOS (arm64)");
     expect(line).toContain("node=v20");
     expect(line).toContain("model=anthropic/claude");
diff --git a/src/agents/system-prompt.ts b/src/agents/system-prompt.ts
index dbf30414f..772f154e4 100644
--- a/src/agents/system-prompt.ts
+++ b/src/agents/system-prompt.ts
@@ -160,6 +160,7 @@ export function buildAgentSystemPrompt(params: {
     defaultModel?: string;
     channel?: string;
     capabilities?: string[];
+    repoRoot?: string;
   };
   messageToolHints?: string[];
   sandboxInfo?: {
@@ -570,6 +571,7 @@ export function buildRuntimeLine(
     node?: string;
     model?: string;
     defaultModel?: string;
+    repoRoot?: string;
   },
   runtimeChannel?: string,
   runtimeCapabilities: string[] = [],
@@ -578,6 +580,7 @@ export function buildRuntimeLine(
   return `Runtime: ${[
     runtimeInfo?.agentId ? `agent=${runtimeInfo.agentId}` : "",
     runtimeInfo?.host ? `host=${runtimeInfo.host}` : "",
+    runtimeInfo?.repoRoot ? `repo=${runtimeInfo.repoRoot}` : "",
     runtimeInfo?.os
       ? `os=${runtimeInfo.os}${runtimeInfo?.arch ? ` (${runtimeInfo.arch})` : ""}`
       : runtimeInfo?.arch
diff --git a/src/auto-reply/reply/commands-context-report.ts b/src/auto-reply/reply/commands-context-report.ts
index 5ba3aedc9..ac93e5fed 100644
--- a/src/auto-reply/reply/commands-context-report.ts
+++ b/src/auto-reply/reply/commands-context-report.ts
@@ -102,6 +102,8 @@ async function resolveContextReport(
   const { runtimeInfo, userTimezone, userTime, userTimeFormat } = buildSystemPromptParams({
     config: params.cfg,
     agentId: sessionAgentId,
+    workspaceDir,
+    cwd: process.cwd(),
     runtime: {
       host: "unknown",
       os: "unknown",
diff --git a/src/config/schema.ts b/src/config/schema.ts
index cd22e94d9..953205cd6 100644
--- a/src/config/schema.ts
+++ b/src/config/schema.ts
@@ -197,6 +197,7 @@ const FIELD_LABELS: Record<string, string> = {
   "skills.load.watch": "Watch Skills",
   "skills.load.watchDebounceMs": "Skills Watch Debounce (ms)",
   "agents.defaults.workspace": "Workspace",
+  "agents.defaults.repoRoot": "Repo Root",
   "agents.defaults.bootstrapMaxChars": "Bootstrap Max Chars",
   "agents.defaults.envelopeTimezone": "Envelope Timezone",
   "agents.defaults.envelopeTimestamp": "Envelope Timestamp",
@@ -432,6 +433,8 @@ const FIELD_HELP: Record<string, string> = {
   "auth.cooldowns.failureWindowHours": "Failure window (hours) for backoff counters (default: 24).",
   "agents.defaults.bootstrapMaxChars":
     "Max characters of each workspace bootstrap file injected into the system prompt before truncation (default: 20000).",
+  "agents.defaults.repoRoot":
+    "Optional repository root shown in the system prompt runtime line (overrides auto-detect).",
   "agents.defaults.envelopeTimezone":
     'Timezone for message envelopes ("utc", "local", "user", or an IANA timezone string).',
   "agents.defaults.envelopeTimestamp":
diff --git a/src/config/types.agent-defaults.ts b/src/config/types.agent-defaults.ts
index 11f7cf10d..46bd25d64 100644
--- a/src/config/types.agent-defaults.ts
+++ b/src/config/types.agent-defaults.ts
@@ -99,6 +99,8 @@ export type AgentDefaultsConfig = {
   models?: Record<string, AgentModelEntryConfig>;
   /** Agent working directory (preferred). Used as the default cwd for agent runs. */
   workspace?: string;
+  /** Optional repository root for system prompt runtime line (overrides auto-detect). */
+  repoRoot?: string;
   /** Skip bootstrap (BOOTSTRAP.md creation, etc.) for pre-configured deployments. */
   skipBootstrap?: boolean;
   /** Max chars for injected bootstrap files before truncation (default: 20000). */
diff --git a/src/config/zod-schema.agent-defaults.ts b/src/config/zod-schema.agent-defaults.ts
index c6c0ab3b2..fd624bfe3 100644
--- a/src/config/zod-schema.agent-defaults.ts
+++ b/src/config/zod-schema.agent-defaults.ts
@@ -42,6 +42,7 @@ export const AgentDefaultsSchema = z
       )
       .optional(),
     workspace: z.string().optional(),
+    repoRoot: z.string().optional(),
     skipBootstrap: z.boolean().optional(),
     bootstrapMaxChars: z.number().int().positive().optional(),
     userTimezone: z.string().optional(),
diff --git a/src/telegram/bot.create-telegram-bot.accepts-group-messages-mentionpatterns-match-without-botusername.test.ts b/src/telegram/bot.create-telegram-bot.accepts-group-messages-mentionpatterns-match-without-botusername.test.ts
index eae2de919..1d40a6ac5 100644
--- a/src/telegram/bot.create-telegram-bot.accepts-group-messages-mentionpatterns-match-without-botusername.test.ts
+++ b/src/telegram/bot.create-telegram-bot.accepts-group-messages-mentionpatterns-match-without-botusername.test.ts
@@ -226,7 +226,9 @@ describe("createTelegramBot", () => {
     expect(payload.SenderName).toBe("Ada Lovelace");
     expect(payload.SenderId).toBe("99");
     expect(payload.SenderUsername).toBe("ada");
-    expect(payload.Body).toMatch(/^\[Telegram Ops id:42 (\+\d+[smhd] )?2025-01-09 00:00 [^\]]+\]/);
+    expect(payload.Body).toMatch(
+      /^\[Telegram Ops id:42 (\+\d+[smhd] )?2025-01-09 00:00 [^\]]+\]/,
+    );
   });
   it("reacts to mention-gated group messages when ackReaction is enabled", async () => {
     onSpy.mockReset();