diff --git a/apps/opencode-plugin/cli-bridge.test.ts b/apps/opencode-plugin/cli-bridge.test.ts
index 50188e3aa..7ea2f6236 100644
--- a/apps/opencode-plugin/cli-bridge.test.ts
+++ b/apps/opencode-plugin/cli-bridge.test.ts
@@ -7,8 +7,12 @@ import {
   buildCliBridgeEnv,
   buildCliSpawnConfig,
   buildReviewPromptFromBridgeOutcome,
+  formatDetachedPlanReviewMessage,
   formatUserFacingCliStderrLine,
+  getDetachedPlanReviewUrl,
   getRecentAssistantMessages,
+  isOpenChamberRuntime,
+  resolveDetachedPlanReviewPort,
 } from "./cli-bridge";
 import { getReviewDeniedSuffix } from "@plannotator/shared/prompts";
 
@@ -84,6 +88,25 @@ describe("OpenCode CLI bridge helpers", () => {
     expect(formatUserFacingCliStderrLine("Fetching: https://example.com")).toBeUndefined();
   });
 
+  test("detects OpenChamber runtime without recursing in the detached child", () => {
+    expect(isOpenChamberRuntime({ OPENCHAMBER_RUNTIME: "desktop" } as NodeJS.ProcessEnv)).toBe(true);
+    expect(isOpenChamberRuntime({ OPENCHAMBER_RUNTIME: "desktop", PLANNOTATOR_DETACHED_CHILD: "1" } as NodeJS.ProcessEnv)).toBe(false);
+    expect(isOpenChamberRuntime({} as NodeJS.ProcessEnv)).toBe(false);
+  });
+
+  test("chooses a concrete detached review port for immediate OpenChamber URLs", () => {
+    expect(resolveDetachedPlanReviewPort({ PLANNOTATOR_PORT: "4432" } as NodeJS.ProcessEnv)).toBe(4432);
+    expect(resolveDetachedPlanReviewPort({ PLANNOTATOR_PORT: "0" } as NodeJS.ProcessEnv, () => 0)).toBe(19_000);
+    expect(resolveDetachedPlanReviewPort({ PLANNOTATOR_PORT: "bad" } as NodeJS.ProcessEnv, () => 0.5)).toBe(29_000);
+  });
+
+  test("formats the detached OpenChamber review URL message", () => {
+    const url = getDetachedPlanReviewUrl(4432);
+    expect(url).toBe("http://localhost:4432");
+    expect(formatDetachedPlanReviewMessage(url)).toContain("Review UI is starting at http://localhost:4432");
+    expect(formatDetachedPlanReviewMessage(url)).toContain("approval or comments");
+  });
+
   test("resolves Windows CLI commands to an executable without shell mode", () => {
     const dir = mkdtempSync(path.join(tmpdir(), "plannotator-cli-"));
     try {
diff --git a/apps/opencode-plugin/cli-bridge.ts b/apps/opencode-plugin/cli-bridge.ts
index 00dbc8316..16af041d4 100644
--- a/apps/opencode-plugin/cli-bridge.ts
+++ b/apps/opencode-plugin/cli-bridge.ts
@@ -60,6 +60,12 @@ interface RunCliResult {
   exitCode: number | null;
 }
 
+export interface DetachedPlanReviewLaunch {
+  url: string;
+  port: number;
+  message: string;
+}
+
 interface CliSpawnConfig {
   command: string;
   args: string[];
@@ -245,6 +251,127 @@ function logReadyFile(client: OpenCodeClient, readyFile: string, readyLabel: str
   }
 }
 
+export function isOpenChamberRuntime(env: NodeJS.ProcessEnv = process.env): boolean {
+  return Boolean(env.OPENCHAMBER_RUNTIME?.trim()) && env.PLANNOTATOR_DETACHED_CHILD !== "1";
+}
+
+export function resolveDetachedPlanReviewPort(
+  env: NodeJS.ProcessEnv = process.env,
+  random: () => number = Math.random,
+): number {
+  const rawPort = env.PLANNOTATOR_PORT?.trim();
+  if (rawPort) {
+    const parsed = Number.parseInt(rawPort, 10);
+    if (Number.isFinite(parsed) && parsed > 0 && parsed < 65_536) {
+      return parsed;
+    }
+  }
+
+  return 19_000 + Math.floor(random() * 20_000);
+}
+
+export function getDetachedPlanReviewUrl(port: number): string {
+  return `http://localhost:${port}`;
+}
+
+export function formatDetachedPlanReviewMessage(url: string): string {
+  return `[Plannotator] Review UI is starting at ${url}
+
+Open this URL in your browser to review the plan. Do not continue implementation yet; Plannotator will send your approval or comments back into this session when you submit the review.`;
+}
+
+export function startDetachedCliPlanReview(input: {
+  client: OpenCodeClient;
+  planContent: string;
+  cwd?: string;
+  timeoutSeconds: number | null;
+  bridge?: OpenCodeBridgeContext;
+  onResult?: (result: OpenCodePlanReviewResult) => void | Promise<void>;
+  onError?: (error: Error) => void | Promise<void>;
+}): DetachedPlanReviewLaunch {
+  const port = resolveDetachedPlanReviewPort();
+  const url = getDetachedPlanReviewUrl(port);
+  const cwd = input.cwd || process.cwd();
+  const payload = JSON.stringify({
+    plan: input.planContent,
+    timeoutSeconds: input.timeoutSeconds,
+    ...buildBridgePayload(input.bridge),
+  });
+  const env = {
+    ...process.env,
+    ...buildCliBridgeEnv(input.bridge),
+    OPENCHAMBER_RUNTIME: "",
+    PLANNOTATOR_DETACHED_CHILD: "1",
+    PLANNOTATOR_SKIP_BROWSER_OPEN: "1",
+    PLANNOTATOR_PORT: String(port),
+    OPENCODE: "1",
+    PLANNOTATOR_ORIGIN: "opencode",
+    PLANNOTATOR_CWD: cwd,
+  };
+
+  const notifyError = (error: Error) => {
+    log(input.client, "error", `[Plannotator] Detached plan review failed: ${error.message}`);
+    void input.onError?.(error);
+  };
+
+  const bin = getPlannotatorBin();
+  const spawnConfig = buildCliSpawnConfig(bin, ["opencode-plan"]);
+  const child = spawn(spawnConfig.command, spawnConfig.args, {
+    cwd,
+    env,
+    shell: spawnConfig.shell,
+    detached: true,
+    stdio: ["pipe", "pipe", "pipe"],
+  });
+
+  if (!child.stdin || !child.stdout || !child.stderr) {
+    throw new Error("Failed to open pipes for the detached plannotator CLI process.");
+  }
+
+  let stdout = "";
+  let stderr = "";
+  const stderrForwarder = createCliStderrForwarder(input.client);
+
+  child.stdout.setEncoding("utf-8");
+  child.stderr.setEncoding("utf-8");
+  child.stdout.on("data", (chunk) => {
+    stdout += chunk;
+  });
+  child.stderr.on("data", (chunk) => {
+    stderr += chunk;
+    stderrForwarder.push(chunk);
+  });
+  child.on("error", (error: NodeJS.ErrnoException) => {
+    const hint = error.code === "ENOENT"
+      ? "Could not find the plannotator CLI. Install it with: curl -fsSL https://plannotator.ai/install.sh | bash"
+      : error.message;
+    notifyError(new Error(hint));
+  });
+  child.stdin.on("error", (error: Error) => {
+    notifyError(new Error(`Failed to write detached plan payload: ${error.message}`));
+  });
+  child.on("close", (exitCode) => {
+    stderrForwarder.flush();
+    if (exitCode !== 0) {
+      notifyError(new Error(stderr.trim() || `Plannotator CLI exited with code ${exitCode}`));
+      return;
+    }
+
+    try {
+      logCliWarnings(input.client, stderr);
+      const result = parseLastJson<OpenCodePlanReviewResult>(stdout);
+      void input.onResult?.(result);
+    } catch (error) {
+      notifyError(error instanceof Error ? error : new Error(String(error)));
+    }
+  });
+
+  child.stdin.end(payload);
+  log(input.client, "info", `[Plannotator] Starting detached plan review: ${url}`);
+
+  return { url, port, message: formatDetachedPlanReviewMessage(url) };
+}
+
 async function runPlannotatorCli(options: RunCliOptions): Promise<RunCliResult> {
   const readyFile = path.join(
     tmpdir(),
diff --git a/apps/opencode-plugin/index.ts b/apps/opencode-plugin/index.ts
index 3c9ee45c5..c2071dbc7 100644
--- a/apps/opencode-plugin/index.ts
+++ b/apps/opencode-plugin/index.ts
@@ -55,7 +55,9 @@ import {
 } from "./plan-edits";
 import {
   handleCliCommand,
+  isOpenChamberRuntime,
   runCliPlanReview,
+  startDetachedCliPlanReview,
   type OpenCodeBridgeContext,
   type OpenCodePlanReviewResult,
 } from "./cli-bridge";
@@ -635,6 +637,90 @@ Use /plannotator-last or /plannotator-annotate for manual review, or set workflo
           writeFileSync(backingPath, planContent, "utf-8");
 
           const timeoutSeconds = getPlanTimeoutSeconds();
+          if (isOpenChamberRuntime()) {
+            const sendDetachedResult = async (result: OpenCodePlanReviewResult) => {
+              try {
+                if (result.approved) {
+                  try { unlinkSync(backingPath); } catch { /* already gone */ }
+
+                  const shouldSwitchAgent = result.agentSwitch && result.agentSwitch !== 'disabled';
+                  const targetAgent = result.agentSwitch || 'build';
+                  const text = result.feedback
+                    ? getPlanApprovedWithNotesPrompt("opencode", undefined, {
+                        planFilePath: backingPath,
+                        doneMsg: result.savedPath ? `Saved to: ${result.savedPath}` : "",
+                        feedback: result.feedback,
+                        proceedSuffix: shouldSwitchAgent
+                          ? "\n\nProceed with implementation, incorporating these notes where applicable."
+                          : "",
+                      })
+                    : getPlanApprovedPrompt("opencode", undefined, {
+                        planFilePath: backingPath,
+                        doneMsg: result.savedPath ? ` Saved to: ${result.savedPath}` : "",
+                      });
+
+                  await ctx.client.session.prompt({
+                    path: { id: context.sessionID },
+                    body: {
+                      ...(shouldSwitchAgent && { agent: targetAgent }),
+                      parts: [{ type: "text", text }],
+                    },
+                  });
+                  return;
+                }
+
+                const lineNumberedPlan = formatWithLineNumbers(planContent);
+                const totalLines = planContent.split("\n").length;
+                const text = getPlanDeniedPrompt("opencode", undefined, {
+                  toolName: getPlanToolName("opencode"),
+                  planFileRule: "",
+                  feedback: result.feedback || "Plan changes requested",
+                }) + `\n\n## Current Plan (${totalLines} lines)\n\nThe plan below shows the current state with line numbers. Use these exact line numbers in your next \`submit_plan\` call:\n\n\`\`\`\n${lineNumberedPlan}\n\`\`\`\n\nCall \`submit_plan\` with targeted edits to address the feedback above.`;
+
+                await ctx.client.session.prompt({
+                  path: { id: context.sessionID },
+                  body: { parts: [{ type: "text", text }] },
+                });
+              } catch (error) {
+                try {
+                  void ctx.client.app.log({
+                    level: "error",
+                    message: `[Plannotator] Failed to deliver detached plan result: ${error instanceof Error ? error.message : String(error)}`,
+                  });
+                } catch {}
+              }
+            };
+
+            const sendDetachedError = async (error: Error) => {
+              try {
+                await ctx.client.session.prompt({
+                  path: { id: context.sessionID },
+                  body: {
+                    parts: [{
+                      type: "text",
+                      text: `[Plannotator] Failed to complete detached plan review: ${error.message}`,
+                    }],
+                  },
+                });
+              } catch {}
+            };
+
+            try {
+              const launch = startDetachedCliPlanReview({
+                client: ctx.client,
+                planContent,
+                timeoutSeconds,
+                cwd: ctx.directory,
+                bridge: await getBridgeContext(),
+                onResult: sendDetachedResult,
+                onError: sendDetachedError,
+              });
+              return launch.message;
+            } catch (error) {
+              return `[Plannotator] Failed to start detached plan review: ${error instanceof Error ? error.message : String(error)}`;
+            }
+          }
+
           let result: OpenCodePlanReviewResult;
           try {
             result = await runPlanReview({