diff --git a/CLAUDE.md b/CLAUDE.md
index d72ab3a7..49f1b2df 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -30,7 +30,7 @@ pnpm + TypeScript ESM monorepo — four dependency tiers, one-way deps, Node ≥
   - **@cotal-ai/connector-opencode** — OpenCode adapter (native in-process plugin injected via `OPENCODE_CONFIG_CONTENT`; renders the shared `cotal_*` tool specs as plugin tools).
   - **@cotal-ai/cmux** — the cmux integration: a thin driver over the [cmux](https://github.com/) CLI (open/close a tab, send keys) **plus a self-registering `cmux` Runtime**. Importing it registers the runtime with the core `Registry`, so the manager spawns into cmux tabs without depending on this package (opt-in via one import; the `cotal` binary does it).
 - **`implementations/*` — opinionated surfaces** over core (self-contained; never import each other).
-  - **@cotal-ai/cli** — mesh CLI: `up`/`down`, `join`, `watch`, `console` (thin NATS clients), `spawn` — a foreground agent launch reusing the connector's launch recipe — and `setup`, the two-tier guided flow (bundled NATS binary, Claude plugin install, interactive Claude handoff on failures). First run (no `~/.cotal/onboarded.json`) is the full narrated/clack flow; later runs are a compact ensure+status; `setup --full` forces the full flow.
+  - **@cotal-ai/cli** — mesh CLI: `up`/`down`, `join`, `watch`, `console` (thin NATS clients), `spawn` — a foreground agent launch reusing the connector's launch recipe, with `--resume <id>` to late-join an existing Claude Code session onto the mesh (fork by default, `--in-place` to continue the same id) — and `setup`, the two-tier guided flow (bundled NATS binary, Claude plugin install, interactive Claude handoff on failures). First run (no `~/.cotal/onboarded.json`) is the full narrated/clack flow; later runs are a compact ensure+status; `setup --full` forces the full flow.
   - **@cotal-ai/manager** — agent supervisor: a mesh endpoint that spawns/manages nodes via a pluggable `Runtime` (`pty` default / `tmux` / `cmux`), plus its own control-plane commands (`start`/`stop`/`ps`/`attach`) and a WS attach endpoint.
 - **`bin/` — the published `cotal-ai` package**: `cotal.ts` is the composition root for the `cotal` binary — imports the implementations it wants (which self-register their commands) and runs them. `npx cotal-ai` with no args runs the guided `setup`.
 - **`examples/*` — use-cases** (composition roots; private, never published).
diff --git a/docs/claude-code-integration.md b/docs/claude-code-integration.md
index 14c689d0..7e44cad2 100644
--- a/docs/claude-code-integration.md
+++ b/docs/claude-code-integration.md
@@ -55,6 +55,18 @@ claude --strict-mcp-config --mcp-config '{"mcpServers":{"cotal":{"command":"node
   stays inert and never joins — so an operator's own sessions in the repo don't appear as stray peers.
 - **Hands-free spawn.** The dev-channels flag prints a one-time "Enter to confirm" prompt; the PTY
   runtime auto-clears it via `LaunchSpec.confirm`, so a supervised launch needs no keypress.
+- **Late-join an existing session.** A live `claude` can't be hot-attached (MCP/hooks/channel are
+  launch-bound), so late-join means relaunching a session's history wired to the mesh — a `--resume
+  <id>` pass-through on `cotal spawn <name>` (and `cotal start`), where `<id>` is the transcript
+  filename under `~/.claude/projects/<encoded-cwd>/<id>.jsonl`. Two modes:
+  - **fork (default)** — `--resume <id> --fork-session`: claude replays the transcript into a fresh,
+    cotal-equipped process under a **new** id, so the original keeps its identity and runs untouched
+    (the mesh peer is a copy that diverges from the fork point).
+  - **`--in-place`** (spawn only) — plain `--resume <id>`: the **same** id/transcript continues, now
+    mesh-wired. Exit the original first (two live processes writing one transcript corrupts it).
+
+  Both skip the auto-submitted greeting (the session already has context) and compose with the MCP
+  isolation above. Resume is claude-only; the other connectors ignore the flag (like `prompt`).
 
 ## Agent files (persona + identity)
 
diff --git a/docs/getting-started.md b/docs/getting-started.md
index b251e9be..ff0849a3 100644
--- a/docs/getting-started.md
+++ b/docs/getting-started.md
@@ -68,6 +68,7 @@ feedback). Prefer commands?
 cotal go                             # open or resume your session (reuses what's up)
 cotal spawn me                       # the session you drive (consults david/sven)
 cotal spawn david                    # ask the engineer (or sven, the guide)
+cotal spawn me --resume <id>         # late-join an existing Claude session onto the mesh
 cotal console --space main           # live mesh view in the terminal (TUI)
 cotal web --space main               # (re)open the browser dashboard
 cotal down                           # stop the background mesh + dashboard + manager
diff --git a/extensions/connector-claude-code/src/extension.ts b/extensions/connector-claude-code/src/extension.ts
index 1bddd1b8..45fde598 100644
--- a/extensions/connector-claude-code/src/extension.ts
+++ b/extensions/connector-claude-code/src/extension.ts
@@ -45,12 +45,24 @@ export const claudeConnector: Connector = {
     if (opts.creds) env.COTAL_CREDS = opts.creds;
     if (opts.servers) env.COTAL_SERVERS = opts.servers;
 
-    // A leading positional is claude's first message, auto-submitted on start —
-    // so a driving session can greet the operator the moment it joins.
-    const args = opts.prompt
+    // A leading positional is claude's first message, auto-submitted on start — so a driving
+    // session can greet the operator the moment it joins. A resumed session already carries its
+    // own context, so skip the greeting and reattach the prior conversation instead.
+    const args = opts.prompt && !opts.resume
       ? [opts.prompt, "--dangerously-load-development-channels", CHANNEL_REF]
       : ["--dangerously-load-development-channels", CHANNEL_REF];
 
+    // Resume a prior conversation into the mesh. By default --fork-session makes claude mint a
+    // fresh session id from the resumed history, so the original session this id points at keeps
+    // running untouched (we adopt its context, not its identity) — the safe choice when it may
+    // still be alive. With fork === false (an in-place late-join, original already exited) we omit
+    // it so the *same* session id continues. Composes with the strict-MCP isolation below — either
+    // way the process still loads only the cotal server.
+    if (opts.resume) {
+      args.push("--resume", opts.resume);
+      if (opts.fork !== false) args.push("--fork-session");
+    }
+
     // Pre-allow fetching the public Cotal docs so a doc-grounded persona (e.g. david)
     // can look something up under `npx` (no repo on disk) without prompting the operator
     // mid-demo. Additive under the default permission mode — leaves other tools as-is.
diff --git a/implementations/cli/src/commands/spawn.ts b/implementations/cli/src/commands/spawn.ts
index 937f172c..716ae4d4 100644
--- a/implementations/cli/src/commands/spawn.ts
+++ b/implementations/cli/src/commands/spawn.ts
@@ -44,6 +44,8 @@ export async function spawn(argv: string[]): Promise<void> {
       agent: { type: "string" },
       role: { type: "string" },
       prompt: { type: "string" },
+      resume: { type: "string" }, // resume a prior Claude session id (claude-only; others ignore)
+      "in-place": { type: "boolean" }, // continue the same id instead of forking a fresh one
     },
   });
 
@@ -52,7 +54,7 @@ export async function spawn(argv: string[]): Promise<void> {
   const ref = values.config ?? positionals[0] ?? values.name;
   if (!ref) {
     console.error(
-      "usage: cotal spawn <name-or-path> | --config <path> | --name <n>  [--agent <a>] [--role <r>] [--space <s>] [--server <url>] [--prompt <text>]",
+      "usage: cotal spawn <name-or-path> | --config <path> | --name <n>  [--agent <a>] [--role <r>] [--resume <id>] [--in-place] [--space <s>] [--server <url>] [--prompt <text>]",
     );
     process.exit(1);
   }
@@ -115,6 +117,9 @@ export async function spawn(argv: string[]): Promise<void> {
     servers: server,
     configPath: path,
     prompt: values.prompt,
+    resume: values.resume,
+    // Fork by default (safe — original session untouched); --in-place continues the same id.
+    fork: values["in-place"] ? false : undefined,
   });
 
   console.error(
diff --git a/implementations/cli/src/index.ts b/implementations/cli/src/index.ts
index 60187997..70c87ae4 100644
--- a/implementations/cli/src/index.ts
+++ b/implementations/cli/src/index.ts
@@ -86,7 +86,7 @@ const baseCommands: Command[] = [
     name: "spawn",
     group: "Agents",
     summary:
-      "launch an agent in this terminal from a file — spawn <name-or-path> | --name <n> --config <path> [--agent <a>] [--role <r>]",
+      "launch an agent in this terminal from a file — spawn <name-or-path> | --name <n> --config <path> [--agent <a>] [--role <r>] [--resume <id>] [--in-place]",
     run: spawn,
   },
   {
diff --git a/implementations/manager/src/commands.ts b/implementations/manager/src/commands.ts
index 058e1e37..191f5e93 100644
--- a/implementations/manager/src/commands.ts
+++ b/implementations/manager/src/commands.ts
@@ -39,6 +39,7 @@ function parse(argv: string[]): Values {
       agent: { type: "string" },
       config: { type: "string" },
       creds: { type: "string" },
+      resume: { type: "string" },
       "console-port": { type: "string" },
       drive: { type: "boolean" },
       spawn: { type: "string" }, // comma-separated agent names to pre-spawn at startup
@@ -108,6 +109,7 @@ async function start(argv: string[]): Promise<void> {
     role: v.role,
     agent: v.agent,
     config: v.config,
+    resume: v.resume,
   }, v.creds);
   failIfNotOk(reply);
   const d = reply.data as { name: string; role?: string; agent: string; mode: string };
@@ -378,7 +380,7 @@ const managerCommands: Command[] = [
     name: "start",
     group: "Control plane",
     summary:
-      "ask the manager to spawn an agent — --name <n> [--role <r>] [--agent <a>] [--config <file>] (auto-discovers .cotal/agents/<n>.md)",
+      "ask the manager to spawn an agent — --name <n> [--role <r>] [--agent <a>] [--config <file>] [--resume <id>] (auto-discovers .cotal/agents/<n>.md)",
     run: start,
   },
   {
diff --git a/implementations/manager/src/manager.ts b/implementations/manager/src/manager.ts
index 4417b9b4..76a0cf2a 100644
--- a/implementations/manager/src/manager.ts
+++ b/implementations/manager/src/manager.ts
@@ -231,6 +231,7 @@ export class Manager {
         creds: credsPath,
         servers: this.servers,
         configPath,
+        resume: args.resume ? String(args.resume) : undefined,
       });
       handle = this.runtime.spawn(name, spec, this.workspaceRoot);
     } catch (e) {
diff --git a/package.json b/package.json
index 7723a526..d5761d78 100644
--- a/package.json
+++ b/package.json
@@ -27,7 +27,8 @@
     "smoke:attention:auth": "tsx extensions/connector-core/attention-auth.smoke.ts",
     "smoke:feedback": "tsx extensions/connector-core/feedback.smoke.ts",
     "smoke:attach": "tsx implementations/manager/attach.smoke.ts",
-    "smoke:install": "tsx implementations/cli/install.smoke.ts"
+    "smoke:install": "tsx implementations/cli/install.smoke.ts",
+    "smoke:resume": "tsx resume.smoke.ts"
   },
   "dependencies": {
     "@cotal-ai/cli": "workspace:*",
diff --git a/packages/core/src/connector.ts b/packages/core/src/connector.ts
index 29e7a74c..297ab63e 100644
--- a/packages/core/src/connector.ts
+++ b/packages/core/src/connector.ts
@@ -21,6 +21,17 @@ export interface LaunchOpts {
    *  that support an auto-submitted first prompt (Claude Code) deliver it; others
    *  ignore it. Used to make a driving session greet the operator on launch. */
   prompt?: string;
+  /** Resume a prior session of this agent type instead of starting fresh — the
+   *  connector-specific session id to reattach. Like {@link prompt}, only connectors
+   *  that support resuming apply it (the Claude connector forks it: `--resume <id>
+   *  --fork-session`); others ignore it. */
+  resume?: string;
+  /** When resuming, whether to fork the session into a fresh id (`--fork-session`) so the
+   *  original keeps running untouched, vs. continue the *same* session in place. Defaults
+   *  to forking — the safe choice when the original may still be alive (two live processes
+   *  must never share one transcript). `cotal spawn --in-place` sets it false to continue
+   *  the same id after the original has exited. Ignored unless `resume` is set. */
+  fork?: boolean;
 }
 
 /** A recipe for starting an agent as a mesh node — command, args, and extra env. */
diff --git a/resume.smoke.ts b/resume.smoke.ts
new file mode 100644
index 00000000..e6e8e842
--- /dev/null
+++ b/resume.smoke.ts
@@ -0,0 +1,43 @@
+/**
+ * Resume launch composition — argv assertions (no mesh). Verifies the claude connector folds
+ * `--resume <id> --fork-session` into the launch while keeping the strict-MCP isolation and
+ * dropping the auto-submitted greeting, and that the `--in-place` fork toggle drops `--fork-session`.
+ * Resume is claude-only (other connectors ignore the flag, like `prompt`).
+ * Run: pnpm smoke:resume
+ */
+import { strict as assert } from "node:assert";
+import { claudeConnector } from "@cotal-ai/connector-claude-code";
+
+let pass = 0;
+const check = (name: string, cond: boolean, extra?: unknown) => {
+  assert.ok(cond, `${name}${extra !== undefined ? ` — ${JSON.stringify(extra)}` : ""}`);
+  pass++;
+  console.log(`  ✓ ${name}`);
+};
+
+const base = { space: "rs", name: "canary" };
+
+// claude: resume folds in `--resume <id> --fork-session` and keeps the strict-MCP isolation.
+const spec = claudeConnector.buildLaunch({ ...base, resume: "sess-123" });
+const a = spec.args;
+check("claude args include --resume", a.includes("--resume"), a);
+check("--resume is immediately followed by the session id", a[a.indexOf("--resume") + 1] === "sess-123", a);
+check("--fork-session present (original session not hijacked)", a.includes("--fork-session"), a);
+check("strict-mcp isolation preserved alongside resume", a.includes("--strict-mcp-config"), a);
+
+// The greeting prompt is skipped on resume (a resumed session already has its context); without
+// resume the prompt IS the leading positional (auto-submitted).
+const resumedWithPrompt = claudeConnector.buildLaunch({ ...base, resume: "sess-123", prompt: "hello there" });
+check("greeting prompt is NOT auto-submitted on resume", !resumedWithPrompt.args.includes("hello there"), resumedWithPrompt.args);
+const freshWithPrompt = claudeConnector.buildLaunch({ ...base, prompt: "hello there" });
+check("greeting prompt IS the leading positional when not resuming", freshWithPrompt.args[0] === "hello there", freshWithPrompt.args);
+
+// fork toggle: `cotal spawn --in-place` (fork:false) continues the SAME id — keeps --resume,
+// drops --fork-session — while the default (fork undefined) still forks. Powers the late-join modes.
+const inPlace = claudeConnector.buildLaunch({ ...base, resume: "sess-123", fork: false });
+check("in-place resume keeps --resume", inPlace.args.includes("--resume"), inPlace.args);
+check("in-place resume omits --fork-session (same id continues)", !inPlace.args.includes("--fork-session"), inPlace.args);
+check("default resume still forks when fork is unset", spec.args.includes("--fork-session"), spec.args);
+
+console.log(`\nresume smoke: ${pass} checks passed`);
+process.exit(0);