feat(lsp,cwd): LSP integration + per-conversation cwd; fix cache-warming cache bust

LSP + per-conversation CWD feature:
- new bundled `lsp` extension: hand-rolled JSON-RPC codec (framing/rpc), lazy
  one-server-per-(serverID,root), per-cwd config resolution, on-demand `lsp` tool
- `conversation-store`: getCwd/setCwd (cwdKey); `session-orchestrator` defaults a
  turn's cwd from the store
- `transport-http`: cwd + lsp status endpoints; wire types in transport-contract
- host-bin: register lsp; config wiring

Cache-warming fix (the warm read 0% on the first reheat after a message):
- warm assembled tools under a different cwd than the real turn (a reheat sends no
  cwd, and the warm service had no store fallback). The skills filter rewrites the
  cwd-sensitive `load_skill` description, so the tools block — the first bytes of
  the prompt-cache prefix — diverged and the cache missed entirely. Warm now
  resolves cwd as opts.cwd ?? conversationStore.getCwd(), mirroring handleMessage.
- capture warm sends as `provider.request` spans flagged `warm:true` (thread a
  child logger into providerOpts) so warm vs real bodies are diffable (obs §3.1).
- kernel logger: span-close now merges child-bound attrs like span-open, so a
  `warm:true` query finds the closed span (with usage/status), not just the open.

Tests: warm forwards a warm-flagged logger; warm falls back to stored cwd; logger
open/close attr consistency. Full suite green (873).

1 files changed, 51 insertions, 0 deletions

diff --git a/packages/lsp/src/root.test.ts b/packages/lsp/src/root.test.ts
new file mode 100644
index 0000000..ffe2e31
--- /dev/null
+++ b/packages/lsp/src/root.test.ts
@@ -0,0 +1,51 @@
+import { describe, expect, it } from "vitest";
+import { findRoot } from "./root.js";
+
+describe("root", () => {
+	it("findRoot returns nearest marker ancestor bounded by cwd", async () => {
+		const existingFiles = new Set([
+			"/project/src/components/tsconfig.json",
+			"/project/tsconfig.json",
+		]);
+
+		const result = await findRoot(
+			"/project/src/components/widgets",
+			"/project",
+			["tsconfig.json"],
+			async (path) => existingFiles.has(path),
+		);
+
+		expect(result).toBe("/project/src/components");
+	});
+
+	it("falls back to cwd", async () => {
+		const result = await findRoot(
+			"/project/src/deep/nested",
+			"/project",
+			["tsconfig.json"],
+			async () => false,
+		);
+
+		expect(result).toBe("/project");
+	});
+
+	it("finds marker at start directory", async () => {
+		const existingFiles = new Set(["/project/tsconfig.json"]);
+
+		const result = await findRoot("/project", "/project", ["tsconfig.json"], async (path) =>
+			existingFiles.has(path),
+		);
+
+		expect(result).toBe("/project");
+	});
+
+	it("respects cwd boundary", async () => {
+		const existingFiles = new Set(["/tsconfig.json"]);
+
+		const result = await findRoot("/project/src", "/project", ["tsconfig.json"], async (path) =>
+			existingFiles.has(path),
+		);
+
+		expect(result).toBe("/project");
+	});
+});