Add mechanicus-session-names extension

Auto-generates a flavored session name on session_start when the
session is new and has no name yet. Format:
  "<Adj>-<Noun> · <3-digit>"
e.g. "Sacred-Cogitation · 042", "Heretek-Datalink · 717".

18 adjectives × 18 nouns × 1000 = 324000 unique names. Auto-naming is
scoped to reason === "new"; resume/fork/reload/startup are untouched.

Command: /mechanicus-rename generates a fresh name for the current
session.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.gitignore

@@ -13,6 +13,7 @@
 !/local-llama.ts
 !/markdown-body-color.ts
 !/mechanicus-banner.ts
+!/mechanicus-session-names.ts
 !/mechanicus-thinking-label.ts
 !/scripts/
 !/themes/

mechanicus-session-names.ts

@@ -0,0 +1,90 @@
+/**
+ * mechanicus-session-names — auto-generate a flavored session name on
+ * session_start if the session doesn't already have one.
+ *
+ * Name format: "<Adjective>-<Noun> · <3-digit>"
+ *   e.g. "Sacred-Cogitation · 042", "Corrupted-Datalink · 119"
+ *
+ * Collision space: 18 × 18 × 1000 = 324000 unique names. Good enough.
+ *
+ * Commands:
+ *   /mechanicus-rename   Generate a new random name for the current session
+ */
+
+import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+
+const ADJECTIVES = [
+	"Sacred",
+	"Blessed",
+	"Sanctified",
+	"Forbidden",
+	"Corrupted",
+	"Heretek",
+	"Ancient",
+	"Binary",
+	"Silicon",
+	"Warp-touched",
+	"Scrapcode",
+	"Soul-harvested",
+	"Nurgle-tainted",
+	"Omnissian",
+	"Cogitator-bound",
+	"Machine-cursed",
+	"Rune-marked",
+	"Daemon-whispered",
+];
+
+const NOUNS = [
+	"Cogitation",
+	"Computation",
+	"Datalink",
+	"Litany",
+	"Ritual",
+	"Invocation",
+	"Binaric-Cant",
+	"Machine-Spirit",
+	"Servitor",
+	"Cogfragment",
+	"Forge-Thread",
+	"Tech-Rite",
+	"Soul-Harvest",
+	"Protocol",
+	"Canticle",
+	"Incantation",
+	"Anointment",
+	"Cogsworn",
+];
+
+function pick<T>(arr: readonly T[]): T {
+	return arr[Math.floor(Math.random() * arr.length)]!;
+}
+
+function generate(): string {
+	const n = String(Math.floor(Math.random() * 1000)).padStart(3, "0");
+	return `${pick(ADJECTIVES)}-${pick(NOUNS)} · ${n}`;
+}
+
+export default function (pi: ExtensionAPI) {
+	pi.on("session_start", async (event, ctx) => {
+		// Only auto-name brand-new sessions. Skip resume/fork/reload/startup
+		// — they already have a name from before or are intentionally unnamed
+		// by the user.
+		if (event.reason !== "new") return;
+		if (pi.getSessionName()) return;
+
+		const name = generate();
+		pi.setSessionName(name);
+		if (ctx.hasUI) {
+			ctx.ui.notify(`Session consecrated: ${name}`, "info");
+		}
+	});
+
+	pi.registerCommand("mechanicus-rename", {
+		description: "Re-consecrate the current session with a fresh mechanicus name",
+		handler: async (_args, ctx) => {
+			const name = generate();
+			pi.setSessionName(name);
+			ctx.ui.notify(`Session re-consecrated: ${name}`, "info");
+		},
+	});
+}