fix: revert jsonl.ts to inline implementation — @gsd-build/rpc-client not available at source-level test time in CI

The re-export from @gsd-build/rpc-client fails in CI because tests run against
TypeScript source (--experimental-strip-types) before any build step. The npm
dependency resolves to node_modules/ which requires dist/ to exist. Reverting
to the original inline implementation eliminates the cross-package dependency
for source-level imports.

package-lock.json

@@ -9221,7 +9221,6 @@
       "name": "@gsd/pi-coding-agent",
       "version": "2.52.0",
       "dependencies": {
-        "@gsd-build/rpc-client": "^2.52.0",
         "@mariozechner/jiti": "^2.6.2",
         "@silvia-odwyer/photon-node": "^0.3.4",
         "chalk": "^5.5.0",

packages/pi-coding-agent/package.json

@@ -20,7 +20,6 @@
     "copy-assets": "node scripts/copy-assets.cjs"
   },
   "dependencies": {
-    "@gsd-build/rpc-client": "^2.52.0",
     "@mariozechner/jiti": "^2.6.2",
     "@silvia-odwyer/photon-node": "^0.3.4",
     "chalk": "^5.5.0",

packages/pi-coding-agent/src/modes/rpc/jsonl.ts

@@ -1 +1,64 @@
-export { serializeJsonLine, attachJsonlLineReader } from '@gsd-build/rpc-client';
+import type { Readable } from "node:stream";
+import { StringDecoder } from "node:string_decoder";
+
+/**
+ * Serialize a single strict JSONL record.
+ *
+ * Framing is LF-only. Payload strings may contain other Unicode separators such as
+ * U+2028 and U+2029. Clients must split records on `\n` only.
+ */
+export function serializeJsonLine(value: unknown): string {
+	return `${JSON.stringify(value)}\n`;
+}
+
+/**
+ * Attach an LF-only JSONL reader to a stream.
+ *
+ * This intentionally does not use Node readline. Readline splits on additional
+ * Unicode separators that are valid inside JSON strings and therefore does not
+ * implement strict JSONL framing.
+ */
+export function attachJsonlLineReader(stream: Readable, onLine: (line: string) => void): () => void {
+	const decoder = new StringDecoder("utf8");
+	let buffer = "";
+
+	const emitLine = (line: string) => {
+		onLine(line.endsWith("\r") ? line.slice(0, -1) : line);
+	};
+
+	const onData = (chunk: string | Buffer) => {
+		buffer += typeof chunk === "string" ? chunk : decoder.write(chunk);
+
+		while (true) {
+			const newlineIndex = buffer.indexOf("\n");
+			if (newlineIndex === -1) {
+				return;
+			}
+
+			emitLine(buffer.slice(0, newlineIndex));
+			buffer = buffer.slice(newlineIndex + 1);
+		}
+	};
+
+	const onEnd = () => {
+		buffer += decoder.end();
+		if (buffer.length > 0) {
+			emitLine(buffer);
+			buffer = "";
+		}
+	};
+
+	const onError = (_err: Error) => {
+		// Stream errors are non-fatal for JSONL reading
+	};
+
+	stream.on("data", onData);
+	stream.on("end", onEnd);
+	stream.on("error", onError);
+
+	return () => {
+		stream.off("data", onData);
+		stream.off("end", onEnd);
+		stream.off("error", onError);
+	};
+}