Add mechanicus-status-line extension

Adds a dark-mechanicum status line to pi's footer via ctx.ui.setStatus.
The default footer automatically renders registered extension statuses
on a third line below cwd + stats.

- 15 status strings (HERETEK FORGE · ACTIVE, VASHTORR NETWORK · ONLINE,
  etc.), pseudo-randomly picked.
- Seeded on session_start, rotated on every turn_end. Status persists
  between turns so it doesn't flicker during input.
- Coloured: ⚙ prefix in warning/gold, body in muted/bronze.
- Commands: /mechanicus-status-cycle (force new), /mechanicus-status-off.

Chosen as an additive approach over full footer replacement: avoids
reimplementing pi's token/cost/context-usage computation just to colour
them; pi's native stats remain intact.

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

.gitignore

@@ -14,6 +14,7 @@
 !/markdown-body-color.ts
 !/mechanicus-banner.ts
 !/mechanicus-session-names.ts
+!/mechanicus-status-line.ts
 !/mechanicus-thinking-label.ts
 !/scripts/
 !/themes/

mechanicus-status-line.ts

@@ -0,0 +1,72 @@
+/**
+ * mechanicus-status-line — adds a dark-mechanicum flavor line to pi's
+ * footer via ctx.ui.setStatus.
+ *
+ * The default footer auto-renders registered extension statuses on a third
+ * line below the cwd + stats. We register one key ("mechanicus") and rotate
+ * its value on each turn_end so the line changes after every assistant
+ * response. On session_start the status is seeded with a random entry so
+ * it's present from the first render.
+ *
+ * Colour: warning (gilded gold) prefix glyph + muted (aged bronze) body.
+ */
+
+import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
+
+const STATUSES = [
+	"HERETEK FORGE · ACTIVE",
+	"VASHTORR NETWORK · ONLINE",
+	"SCRAPCODE CIRCUITRY · OPERATIONAL",
+	"BLOOD-FORGE · CYCLING",
+	"BINARY CANT · CORRUPTED",
+	"DAEMON-MACHINE INTERFACE · STABLE",
+	"COGITATOR · HUNGERING",
+	"WARP CURRENTS · CHANNELING",
+	"TECH-RITE · IN PROGRESS",
+	"MACHINE-SPIRIT · POSSESSED",
+	"SOUL-HARVEST · IMMINENT",
+	"RITE OF CORRUPTION · OBSERVED",
+	"NURGLE'S ROT · PERMEATING",
+	"CHAOS ASCENDANT",
+	"OMNISSIAH IS WEAK",
+];
+
+function pick<T>(arr: readonly T[]): T {
+	return arr[Math.floor(Math.random() * arr.length)]!;
+}
+
+export default function (pi: ExtensionAPI) {
+	const applyStatus = (ctx: any, body?: string) => {
+		if (!ctx.hasUI) return;
+		const text = body ?? pick(STATUSES);
+		const theme = ctx.ui.theme;
+		const line = `${theme.fg("warning", "⚙")} ${theme.fg("muted", text)}`;
+		ctx.ui.setStatus("mechanicus", line);
+	};
+
+	pi.on("session_start", async (_event, ctx) => {
+		applyStatus(ctx);
+	});
+
+	// Rotate after every assistant response so the line feels alive but not
+	// frantic. Between turns the last value persists.
+	pi.on("turn_end", async (_event, ctx) => {
+		applyStatus(ctx);
+	});
+
+	pi.registerCommand("mechanicus-status-cycle", {
+		description: "Force a new mechanicum status line immediately",
+		handler: async (_args, ctx) => {
+			applyStatus(ctx);
+			ctx.ui.notify("Status re-transmuted.", "info");
+		},
+	});
+
+	pi.registerCommand("mechanicus-status-off", {
+		description: "Remove the mechanicum status line from the footer",
+		handler: async (_args, ctx) => {
+			ctx.ui.setStatus("mechanicus", undefined);
+			ctx.ui.notify("Status line cleared.", "info");
+		},
+	});
+}