feat(resume): Resume in the kebab menu (A1) + harden the resume kickoff (A2)

A1 — SessionMenu gains a Resume item, gated to status!=="finalized" && !archived
(matching the backend's 409 read-only guard), wired in AppShell to doResume ->
POST /sessions/:id/resume. SessionMenu.test.tsx (3 tests); frontend 96/96, tsc clean.

A2 — diagnosis-first clean-room repro driving `pi --mode rpc` with the backend's
exact resume handshake shows the cold-start stall NO LONGER reproduces on pi
0.79.4 (8/8 chained into `tht session show` + `read SKILL.md` in-turn, fresh and
partway sessions). The earlier narrate-and-stop predates the pi upgrade.
Defense-in-depth anyway: RIPRENDI_KICKOFF hardened to force the in-turn tool call
(gate_resume_kickoff.test.js + live regression 2/2). Gate JS 34/34.

PROJECT_STATE open-item #1 (resume stall) flipped to RESOLVED; cross-model resume
robustness folded into workstream G.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

harness/.pi/extensions/gate/__tests__/gate_resume_kickoff.test.js

@@ -0,0 +1,21 @@
+const test = require("node:test");
+const assert = require("node:assert");
+const { createFakePi } = require("./fake_pi_runtime.js");
+const installGate = require("../../tht-gate.js").default ?? require("../../tht-gate.js");
+
+// Workstream A (defense-in-depth): the resume cold-start stall (model narrates step 1
+// then ends the turn without the tool call) no longer reproduces on pi 0.79.4, but the
+// resume kickoff is hardened to force the in-turn tool call so weaker/older models don't
+// regress into a dropped turn.
+
+test("the resume kickoff injects the bootstrap steps and forces in-turn action", async () => {
+  const { pi } = createFakePi();
+  installGate(pi);
+  await pi.emit("input", { source: "rpc", text: "/riprendi-sessione 2026-06-30-000000-x" });
+  const injected = await pi.emit("before_agent_start", { systemPrompt: "" });
+  const text = injected?.systemPrompt ?? "";
+  assert.match(text, /tht session show/); // the resume kickoff is the one injected
+  // hardening: act now, in this same turn; do not stop after merely stating intent.
+  assert.match(text, /in QUESTO stesso turno/i);
+  assert.match(text, /NON terminare il turno/i);
+});

harness/.pi/extensions/tht-gate.js

@@ -104,6 +104,9 @@ const RIPRENDI_KICKOFF =
 	"comando di shell ne' `/skill:...`).\n" +
 	"3. Determina l'ultima fase completata dai fatti persistiti (le decisioni sono la verita': " +
 	"cio' che non e' registrato non e' avvenuto) e riprendi da li'.\n" +
+	"Esegui i passi 1-2 ORA, in QUESTO stesso turno, chiamando subito i tool (`bash` per " +
+	"`tht session show`, `read` per la skill): NON limitarti a dichiarare l'intenzione e NON " +
+	"terminare il turno prima di aver chiamato i tool.\n" +
 	"Valgono le stesse regole non negoziabili: una domanda per volta, conferma esplicita, tool " +
 	"reviewer_*, niente phase advance/reopen o decision add da shell, una fase alla volta.";