diff --git a/experimental/papyrus/TESTING.md b/experimental/papyrus/TESTING.md
index c030597..554d8ae 100644
--- a/experimental/papyrus/TESTING.md
+++ b/experimental/papyrus/TESTING.md
@@ -66,7 +66,7 @@ these red, where the client suite stays green.
 - `server-tests/silverwood-contract.test.ts` — the wrapper (`services/silverwood.ts`) argv
   contract: create/get/list/rename/archive, kv, and the full session lifecycle. Native-free.
 - `server-tests/api.e2e.test.ts` — the canvas CUJs through the routes: create / edit /
-  delete a node, session-tab metadata, and error propagation.
+  delete a node, session-tab metadata, session creation/reconnect launch argv, and errors.
 - `server-tests/helpers/` — `forest.ts` (temp forest + `cli()` runner, the TS analog of
   silverwood's `tests/common/mod.rs`) and `app.ts` (stubs the native `bun-pty` — pulled in
   transitively via `sessionManager` — before loading the routes, the same trick the client
@@ -84,8 +84,9 @@ SILVERWOOD_BIN=../silverwood/target/debug/silverwood OPENUI_QUIET=1 bun test ser
 the package root (the "tests" substring would also match `client/tests/`, whose happy-dom
 preload only loads under `client/`).
 
-**Scope / constraints.** Every journey uses silverwood `--checkout-extent skip`, so nothing
-clones — the suite is network-free and runs in the `nix flake check` sandbox via the
+**Scope / constraints.** Basic workstreams use `--checkout-extent skip`; session launch
+journeys use `local-blank` with mocked PTYs, so no agent runs. The suite is network-free
+and runs in the `nix flake check` sandbox via the
 `server-tests` derivation (`flake.nix`), which sets `SILVERWOOD_BIN` to the flake's wrapped
 silverwood. The full create→checkout→live-terminal journey needs network + jj and is **out of
 scope** here, matching silverwood's own `#[ignore]`d e2e split.
diff --git a/experimental/papyrus/server-tests/api.e2e.test.ts b/experimental/papyrus/server-tests/api.e2e.test.ts
index fe0f865..de377cb 100644
--- a/experimental/papyrus/server-tests/api.e2e.test.ts
+++ b/experimental/papyrus/server-tests/api.e2e.test.ts
@@ -145,6 +145,54 @@ describe("papyrus routes → silverwood (in-process, skip-mode)", () => {
     expect(tab(await nodes())).toBeUndefined();
   });
 
+  test.each([
+    "claude-code",
+    "claude-code-noninteractiveshell",
+    "plain-shell",
+    "disk-space",
+  ])("fresh %s session and reconnect use the saved-session command", async (kind) => {
+    const created = await api(
+      "/sessions",
+      jsonInit("POST", { name: "session-ws", path: ["local-blank"], args: [] }),
+    );
+    expect(created.status).toBe(200);
+    const id = created.body.nodeId;
+    const options = kind === "claude-code-noninteractiveshell"
+      ? { "run-direnv-exec": "false" }
+      : {};
+
+    const started = await api(
+      `/sessions/${id}/sessions`,
+      jsonInit("POST", { kind, options }),
+    );
+    expect(started.status).toBe(200);
+    expect(started.body).toMatchObject({ connected: true, kind });
+    const sid = started.body.sessionId;
+    expect((await sw.sessionLs(id))[sid]?.kind).toBe(kind);
+    expect(spawnCalls).toEqual([["session", "run", id, sid]]);
+    expect(sessions.get(sid)?.cwd).toBe(created.body.cwd);
+
+    const disconnected = await api(`/sessions/${id}/sessions/${sid}/disconnect`, {
+      method: "POST",
+    });
+    expect(disconnected.status).toBe(200);
+    expect(sessions.has(sid)).toBe(false);
+    expect((await sw.sessionLs(id))[sid]?.kind).toBe(kind);
+
+    const reconnected = await api(
+      `/sessions/${id}/sessions/connect`,
+      jsonInit("POST", { sessionId: sid }),
+    );
+    expect(reconnected.status).toBe(200);
+    expect(reconnected.body).toMatchObject({ sessionId: sid, connected: true });
+    expect(spawnCalls).toEqual([
+      ["session", "run", id, sid],
+      ["session", "run", id, sid],
+    ]);
+    expect(sessions.get(sid)?.cwd).toBe(created.body.cwd);
+    await api(`/sessions/${id}/sessions/${sid}/disconnect`, { method: "POST" });
+  });
+
   test("fresh codex registers and keeps its title after reconnect", async () => {
     const created = await api(
       "/sessions",
@@ -229,6 +277,10 @@ describe("papyrus routes → silverwood (in-process, skip-mode)", () => {
       jsonInit("POST", { sessionId: durableId }),
     );
     expect(reconnected.status).toBe(200);
+    expect(spawnCalls).toEqual([
+      ["session", "create", "codex", id, "--name", runtimeId],
+      ["session", "run", id, durableId],
+    ]);
     expect(sessions.get(durableId)?.durableSessionId).toBe(durableId);
     const resumed = (await nodes()).find((n) => n.nodeId === id);
     expect(resumed.sessions).toEqual([
diff --git a/experimental/papyrus/server-tests/helpers/app.ts b/experimental/papyrus/server-tests/helpers/app.ts
index 45f7492..efecce1 100644
--- a/experimental/papyrus/server-tests/helpers/app.ts
+++ b/experimental/papyrus/server-tests/helpers/app.ts
@@ -1,9 +1,5 @@
-// Gateway to the real Hono routes for in-process e2e. `server/routes/api.ts` imports
-// `sessionManager.ts`, which statically imports the native `bun-pty`. No sandbox CUJ
-// spawns a PTY (the create route's terminal spawn lives in a background branch that
-// never runs here), so we stub `bun-pty` BEFORE importing the routes — the same
-// technique the client behavioral test uses for the `Terminal` component. This is the
-// only module that loads the routes, so the mock is always registered first.
+// Gateway to the real Hono routes for in-process e2e. Stub native `bun-pty` before
+// importing the routes so session journeys can assert launch argv without running agents.
 
 import { mock } from "bun:test";