2 files changed, 231 insertions, 0 deletions
diff --git a/src/features/cwd-lsp/logic/view-model.test.ts b/src/features/cwd-lsp/logic/view-model.test.ts
new file mode 100644
index 0000000..7bc0aad
--- /dev/null
+++ b/src/features/cwd-lsp/logic/view-model.test.ts
@@ -0,0 +1,101 @@
+import type { LspServerInfo } from "@dispatch/transport-contract";
+import { describe, expect, it } from "vitest";
+import {
+  cwdChanged,
+  isSubmittableCwd,
+  normalizeCwd,
+  summarizeServers,
+  viewLspServer,
+  viewLspServers,
+} from "./view-model";
+
+const server = (over: Partial<LspServerInfo> = {}): LspServerInfo => ({
+  id: "typescript",
+  name: "TypeScript",
+  root: "/home/me/project",
+  extensions: [".ts", ".tsx"],
+  state: "connected",
+  ...over,
+});
+
+describe("cwd helpers", () => {
+  it("normalizeCwd trims surrounding whitespace", () => {
+    expect(normalizeCwd("  /a/b  ")).toBe("/a/b");
+    expect(normalizeCwd("\t/x\n")).toBe("/x");
+  });
+
+  it("isSubmittableCwd is false for empty / whitespace-only", () => {
+    expect(isSubmittableCwd("")).toBe(false);
+    expect(isSubmittableCwd("   ")).toBe(false);
+    expect(isSubmittableCwd("/a")).toBe(true);
+  });
+
+  it("cwdChanged: true only when a non-empty trimmed value differs from current", () => {
+    expect(cwdChanged("/a/b", null)).toBe(true);
+    expect(cwdChanged("/a/b", "/a/b")).toBe(false);
+    expect(cwdChanged("  /a/b  ", "/a/b")).toBe(false); // trim-equal → no change
+    expect(cwdChanged("/a/c", "/a/b")).toBe(true);
+    expect(cwdChanged("", "/a/b")).toBe(false); // empty is not a change (can't clear)
+    expect(cwdChanged("   ", null)).toBe(false);
+  });
+});
+
+describe("viewLspServer", () => {
+  it("connected → success badge, not busy, no error", () => {
+    const v = viewLspServer(server({ state: "connected" }));
+    expect(v.badge).toBe("success");
+    expect(v.statusLabel).toBe("Connected");
+    expect(v.busy).toBe(false);
+    expect(v.error).toBeNull();
+    expect(v.extensionsLabel).toBe(".ts .tsx");
+  });
+
+  it("starting / not-started → busy (spinner) with warning / neutral badge", () => {
+    const starting = viewLspServer(server({ state: "starting" }));
+    expect(starting.badge).toBe("warning");
+    expect(starting.busy).toBe(true);
+
+    const notStarted = viewLspServer(server({ state: "not-started" }));
+    expect(notStarted.badge).toBe("neutral");
+    expect(notStarted.busy).toBe(true);
+  });
+
+  it("error → error badge + surfaces the reason (with a fallback)", () => {
+    const withReason = viewLspServer(server({ state: "error", error: "ENOENT" }));
+    expect(withReason.badge).toBe("error");
+    expect(withReason.busy).toBe(false);
+    expect(withReason.error).toBe("ENOENT");
+
+    const noReason = viewLspServer(server({ state: "error" }));
+    expect(noReason.error).toBe("Failed to start");
+  });
+
+  it("viewLspServers maps a list preserving order", () => {
+    const views = viewLspServers([server({ id: "a" }), server({ id: "b" })]);
+    expect(views.map((v) => v.id)).toEqual(["a", "b"]);
+  });
+});
+
+describe("summarizeServers", () => {
+  it("empty list", () => {
+    expect(summarizeServers([])).toBe("No language servers");
+  });
+
+  it("counts connected / starting / errors", () => {
+    expect(summarizeServers([server({ state: "connected" })])).toBe("1 connected");
+    expect(
+      summarizeServers([
+        server({ id: "a", state: "connected" }),
+        server({ id: "b", state: "error" }),
+      ]),
+    ).toBe("1 connected, 1 error");
+    expect(
+      summarizeServers([
+        server({ id: "a", state: "connected" }),
+        server({ id: "b", state: "starting" }),
+        server({ id: "c", state: "error" }),
+        server({ id: "d", state: "error" }),
+      ]),
+    ).toBe("1 connected, 1 starting, 2 errors");
+  });
+});
diff --git a/src/features/cwd-lsp/logic/view-model.ts b/src/features/cwd-lsp/logic/view-model.ts
new file mode 100644
index 0000000..7642418
--- /dev/null
+++ b/src/features/cwd-lsp/logic/view-model.ts
@@ -0,0 +1,130 @@
+import type { LspServerInfo, LspServerState } from "@dispatch/transport-contract";
+
+/**
+ * Pure core for the cwd-lsp feature — zero DOM, zero effects, zero Svelte.
+ *
+ * The cwd-lsp feature exposes a conversation's per-tab working directory (cwd)
+ * and the live status of the language servers configured for that cwd. This
+ * module holds the pure logic: cwd normalization/validation, the mapping of a
+ * backend `LspServerState` to a display badge, and a one-line server summary.
+ * The effects (the HTTP get/set cwd + get LSP status) are INJECTED via the ports
+ * below; the composition root implements them.
+ */
+
+// ── Injected ports (consumer-defines-port; the composition root adapts the
+//    store's HTTP calls to these shapes). ──────────────────────────────────────
+
+/** Outcome of `PUT /conversations/:id/cwd`; `null` when no real conversation is focused. */
+export type CwdSaveResult =
+  | { readonly ok: true; readonly cwd: string | null }
+  | { readonly ok: false; readonly error: string };
+
+export type SaveCwd = (cwd: string) => Promise<CwdSaveResult | null>;
+
+/** Outcome of `GET /conversations/:id/lsp`; `null` when no real conversation is focused. */
+export type LspStatusResult =
+  | { readonly ok: true; readonly cwd: string | null; readonly servers: readonly LspServerInfo[] }
+  | { readonly ok: false; readonly error: string };
+
+export type LoadLspStatus = () => Promise<LspStatusResult | null>;
+
+// ── cwd helpers ───────────────────────────────────────────────────────────────
+
+/** Trim surrounding whitespace; the backend rejects an empty cwd. */
+export function normalizeCwd(raw: string): string {
+  return raw.trim();
+}
+
+/** Whether a typed cwd is submittable (non-empty after trim). */
+export function isSubmittableCwd(raw: string): boolean {
+  return normalizeCwd(raw).length > 0;
+}
+
+/**
+ * Whether saving `typed` would change the persisted `current` cwd. A no-op save
+ * (unchanged, or empty) should be disabled.
+ */
+export function cwdChanged(typed: string, current: string | null): boolean {
+  const next = normalizeCwd(typed);
+  if (next.length === 0) return false;
+  return next !== (current ?? "");
+}
+
+// ── LSP server status → display view ──────────────────────────────────────────
+
+export type Badge = "success" | "warning" | "error" | "neutral";
+
+export interface LspServerView {
+  readonly id: string;
+  readonly name: string;
+  readonly root: string;
+  /** Space-joined extension list, e.g. ".ts .tsx". */
+  readonly extensionsLabel: string;
+  readonly state: LspServerState;
+  readonly statusLabel: string;
+  readonly badge: Badge;
+  /** True while the state is transient (show a spinner). */
+  readonly busy: boolean;
+  /** The error reason when `state === "error"`, else null. */
+  readonly error: string | null;
+}
+
+/** Map a server's state to a display label + badge severity + busy flag. */
+export function viewLspServer(server: LspServerInfo): LspServerView {
+  let statusLabel: string;
+  let badge: Badge;
+  let busy = false;
+  switch (server.state) {
+    case "connected":
+      statusLabel = "Connected";
+      badge = "success";
+      break;
+    case "starting":
+      statusLabel = "Starting…";
+      badge = "warning";
+      busy = true;
+      break;
+    case "not-started":
+      statusLabel = "Not started";
+      badge = "neutral";
+      busy = true;
+      break;
+    case "error":
+      statusLabel = "Error";
+      badge = "error";
+      break;
+  }
+  return {
+    id: server.id,
+    name: server.name,
+    root: server.root,
+    extensionsLabel: server.extensions.join(" "),
+    state: server.state,
+    statusLabel,
+    badge,
+    busy,
+    error: server.state === "error" ? (server.error ?? "Failed to start") : null,
+  };
+}
+
+export function viewLspServers(servers: readonly LspServerInfo[]): readonly LspServerView[] {
+  return servers.map(viewLspServer);
+}
+
+/** A short one-line summary, e.g. "2 connected" / "1 connected, 1 error". */
+export function summarizeServers(servers: readonly LspServerInfo[]): string {
+  if (servers.length === 0) return "No language servers";
+  let connected = 0;
+  let errored = 0;
+  let pending = 0;
+  for (const s of servers) {
+    if (s.state === "connected") connected++;
+    else if (s.state === "error") errored++;
+    else pending++;
+  }
+  const parts: string[] = [];
+  if (connected > 0) parts.push(`${connected} connected`);
+  if (pending > 0) parts.push(`${pending} starting`);
+  if (errored > 0) parts.push(`${errored} error${errored === 1 ? "" : "s"}`);
+  return parts.join(", ");
+}