Remove post-turn "Cogitated for Xs" inline summary

Caused more trouble than it was worth — even with the context-event
filter stripping the custom message from LLM input, the transcript
entry could still influence the agent in subtle ways (model looking
at it on re-render, extension-interactions, export), and the visual
clutter after every turn wasn't worth the diagnostic value.

Removed:
- pi.registerMessageRenderer("cogitation-summary", ...)
- pi.sendMessage on turn_end
- pi.on("context") filter (no longer needed; nothing to strip)
- Box/Text imports from @mariozechner/pi-tui
- SUMMARY_TYPE constant

Kept:
- Live indicator: ⚙ <quote> · <elapsed> during streaming, with the
  cog pulse and quote rotation and the "Working..." suppression.
- Footer tok/s (lives in mechanicus-footer, not affected).

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

dark-mechanicus-indicator.ts

@@ -1,35 +1,25 @@
 /**
- * dark-mechanicus-indicator — the working indicator AND the post-turn
- * duration summary, all in one extension.
+ * dark-mechanicus-indicator — live working indicator during streaming.
  *
- * Mechanics:
- *
- * 1. Live indicator (during streaming):
  * "⚙ <quote> · <elapsed>"
- *    The ⚙ pulses through four shades of gold (dim → normal → bright →
- *    normal, 250ms each) so a full pulse lasts 1 second. Every second
- *    the frames array is rebuilt with a freshly-formatted elapsed time
- *    and (every 10 seconds) a rotated quote. Because 1s of wall time
- *    equals exactly one pulse cycle, the reset lands at frame 0 and
- *    the animation looks seamless.
  *
- * 2. Post-turn summary:
- *    "✴ Cogitated for <total>"
- *    Injected as a custom message in the transcript right after the
- *    last assistant message, via pi.sendMessage + a registered
- *    message renderer.
+ * The ⚙ pulses through four shades of gold (dim → normal → bright →
+ * normal, 250ms each) so a full pulse lasts 1 second. Every second the
+ * frames array is rebuilt with a freshly-formatted elapsed time and
+ * (every 10 seconds) a rotated quote. Because 1s of wall time equals
+ * exactly one pulse cycle, the reset lands at frame 0 and the animation
+ * looks seamless.
  *
  * Quote pool (45 lines = 15 heretek / 15 dark / 15 operational). Fresh
  * Fisher-Yates shuffle on every turn_start so the order differs per
  * assistant response.
  *
  * Commands:
- *   /dark-mechanicus-indicator-off   Restore pi's default spinner + skip summary
+ *   /dark-mechanicus-indicator-off   Restore pi's default spinner
  *   /dark-mechanicus-indicator-on    Re-enable the mechanicum indicator
  */
 
 import type { ExtensionAPI } from "@mariozechner/pi-coding-agent";
-import { Box, Text } from "@mariozechner/pi-tui";
 
 // ─── Quote pools (15 per category) ───────────────────────────────────────
 
@@ -104,7 +94,6 @@ const PULSE_SHADES = [GOLD_DIM, GOLD_NORMAL, GOLD_BRIGHT, GOLD_NORMAL];
 const FRAME_INTERVAL_MS = 250; // 4 shades × 250ms = 1s pulse
 const TICK_MS = 1000; // rebuild frames once per second
 const QUOTE_DWELL_MS = 10_000; // switch quote every 10 seconds
-const SUMMARY_TYPE = "cogitation-summary";
 
 // ─── Helpers ─────────────────────────────────────────────────────────────
 
@@ -174,37 +163,6 @@ export default function (pi: ExtensionAPI) {
 		});
 	};
 
-	// ── Post-turn summary renderer ───────────────────────────────────
-	pi.registerMessageRenderer(
-		SUMMARY_TYPE,
-		(message, _options, theme) => {
-			const details = message.details as { elapsedMs?: number } | undefined;
-			const elapsedMs = details?.elapsedMs ?? 0;
-			const text = `${theme.fg("accent", "✴")} ${theme.fg(
-				"muted",
-				`Cogitated for ${formatElapsed(elapsedMs)}`,
-			)}`;
-			const box = new Box(1, 0, (t) => theme.bg("customMessageBg", t));
-			box.addChild(new Text(text, 0, 0));
-			return box;
-		},
-	);
-
-	// ── Strip summary messages from LLM context ─────────────────────
-	// pi's convertToLlm() turns every custom message into a `role: "user"`
-	// entry before sending to the provider, so without filtering here the
-	// model sees "Cogitated for 1m 24s" as a user turn and responds to it.
-	// This hook runs before each provider call and returns a messages array
-	// with our summaries removed.
-	pi.on("context", async (event) => {
-		return {
-			messages: event.messages.filter(
-				(m: any) =>
-					!(m.role === "custom" && m.customType === SUMMARY_TYPE),
-			),
-		};
-	});
-
 	// ── Seed at session start so pi's default spinner never appears ──
 	pi.on("session_start", async (_event, ctx) => {
 		suppressWorkingMessage(ctx);
@@ -221,22 +179,9 @@ export default function (pi: ExtensionAPI) {
 		tickerHandle = setInterval(() => applyFrame(ctx), TICK_MS);
 	});
 
-	pi.on("turn_end", async (_event, _ctx) => {
+	pi.on("turn_end", async () => {
 		stopTicker();
-		if (startedAt === null) return;
-		const elapsedMs = Date.now() - startedAt;
 		startedAt = null;
-		if (mode === "off") return;
-		try {
-			await pi.sendMessage({
-				customType: SUMMARY_TYPE,
-				content: `Cogitated for ${formatElapsed(elapsedMs)}`,
-				display: true,
-				details: { elapsedMs },
-			});
-		} catch {
-			// sendMessage may not be available in non-interactive modes; ignore.
-		}
 	});
 
 	pi.on("session_shutdown", async () => {