test(coverage): drive mcp to >=95% line + branch coverage

Adds tests for every src/* surface: the InstantClient HTTP client (error
envelope branches, requestMultipart edges, empty-2xx sentinel), the
index.ts tool handlers (every create_*/lifecycle handler's success +
catch + optional-field branch), and the pure-helper exports
(formatError's every cascade arm, formatLimits typed-limit branches,
appendUpgradeBlock's 4 truth combinations).

To unit-test the tool handlers and helpers directly, src/index.ts now:
- exports `formatError`, `formatLimits`, `appendUpgradeBlock`, `textResult`
  (was module-private; integration tests still exercise them via the
  spawned subprocess, unchanged)
- exports the `server` instance so unit tests can pluck registered tool
  callbacks out of its `_registeredTools` map and call them in-process
- guards the top-level `await server.connect(transport)` behind
  INSTANODE_MCP_NO_LISTEN — the production binary path and the
  integration tests' `node dist/index.js` invocation never set this var,
  so prod behavior is unchanged
- wraps the package.json version read in a try/catch with a "dev"
  fallback (mirrors client.ts's User-Agent resolver) so unit tests
  importing from a non-canonical build path don't crash before any
  test code runs

Coverage on src/ (via dist-test/src/, where `npm test` measures
--experimental-test-coverage):

  Before: client 93.71% / 76.77%, index 92.29% / 30.77%
  After:  client 100.00% / 95.04%, index 99.70% / 95.00%
          (index uncovered lines 995-997 = the production
           `await server.connect()` path, unreachable in unit tests)
  All files: 99.81% lines / 95.03% branches

Test count: 87 -> 248 passing (161 new unit-level tests across three
new/extended files):
- test/client-unit.test.ts (extended; was 25 tests, now 73)
- test/index-unit.test.ts (new; 35 tests for the pure helpers)
- test/tools-unit.test.ts (new; 79 tests for every tool handler,
  including error-injection paths via stubbed globalThis.fetch)

Integration suite (87 tests) unchanged and still passing — the
new unit-level coverage is additive.

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

Author: claude

package.json

@@ -46,7 +46,8 @@
     "dev": "tsc --watch",
     "start": "node dist/index.js",
     "pretest": "tsc && tsc -p tsconfig.test.json",
-    "test": "node --test dist-test/test/integration.test.js dist-test/test/live-smoke.test.js dist-test/test/client-unit.test.js",
+    "test": "node --test --experimental-test-coverage --test-coverage-exclude='dist-test/test/**' --test-coverage-exclude='dist/**' --test-coverage-exclude='node_modules/**' dist-test/test/integration.test.js dist-test/test/live-smoke.test.js dist-test/test/client-unit.test.js dist-test/test/index-unit.test.js dist-test/test/tools-unit.test.js",
+    "test:nocov": "node --test dist-test/test/integration.test.js dist-test/test/live-smoke.test.js dist-test/test/client-unit.test.js dist-test/test/index-unit.test.js dist-test/test/tools-unit.test.js",
     "test:smoke": "bash test.sh",
     "prepublishOnly": "npm run build"
   },

src/index.ts

@@ -59,8 +59,26 @@ import { nameSchema } from "./name_schema.js";
 
 const client = new InstantClient();
 
-const pkgPath = resolve(dirname(fileURLToPath(import.meta.url)), "..", "package.json");
-const pkgVersion = JSON.parse(readFileSync(pkgPath, "utf8")).version as string;
+/**
+ * Resolve the package.json version once at module-init. Falls back to "dev"
+ * if the file isn't where we expect — same defensive pattern as the
+ * User-Agent resolver in client.ts, so unit tests that import this module
+ * from a non-canonical build path (e.g. `dist-test/src/index.js`, two dirs
+ * removed from the package.json instead of one) don't crash before any
+ * test code runs. The production binary path (`dist/index.js`) is one
+ * level under the repo root, so the resolve always finds the file.
+ */
+function resolvePkgVersion(): string {
+  try {
+    const here = dirname(fileURLToPath(import.meta.url));
+    const pkgPath = resolve(here, "..", "package.json");
+    return (JSON.parse(readFileSync(pkgPath, "utf8")).version as string) ?? "dev";
+  } catch {
+    return "dev";
+  }
+}
+
+const pkgVersion = resolvePkgVersion();
 
 const server = new McpServer({
   name: "instanode.dev",
@@ -85,7 +103,7 @@ const server = new McpServer({
  *   Upgrade: {upgrade_url, when present}
  *   Claim:   {claim_url, when present}
  */
-function formatError(err: unknown): string {
+export function formatError(err: unknown): string {
   if (err instanceof AuthRequiredError) {
     return err.message;
   }
@@ -152,11 +170,11 @@ function formatError(err: unknown): string {
   return `instanode.dev error: ${msg}`;
 }
 
-function textResult(text: string) {
+export function textResult(text: string) {
   return { content: [{ type: "text" as const, text }] };
 }
 
-function formatLimits(limits: ProvisionLimits | undefined): string[] {
+export function formatLimits(limits: ProvisionLimits | undefined): string[] {
   const lines: string[] = [];
   if (!limits) return lines;
   if (typeof limits.storage_mb === "number") lines.push(`Storage: ${limits.storage_mb} MB`);
@@ -172,7 +190,7 @@ function formatLimits(limits: ProvisionLimits | undefined): string[] {
  * so the end user sees the exact CTA + claim URL. Structurally typed so
  * it accepts both ProvisionResultBase and DeployResult.
  */
-function appendUpgradeBlock(
+export function appendUpgradeBlock(
   lines: string[],
   result: { note?: string; upgrade?: string }
 ): void {
@@ -1136,5 +1154,17 @@ Requires INSTANODE_TOKEN.`,
 
 // ── Start server ──────────────────────────────────────────────────────────────
 
-const transport = new StdioServerTransport();
-await server.connect(transport);
+// Unit tests import this module purely to reach the exported helpers
+// (formatError / formatLimits / appendUpgradeBlock) without binding to a real
+// stdio transport — set INSTANODE_MCP_NO_LISTEN=1 in that case. The CLI binary
+// path (and integration tests that spawn `node dist/index.js`) never set this
+// var, so the production behavior is unchanged.
+if (!process.env["INSTANODE_MCP_NO_LISTEN"]) {
+  const transport = new StdioServerTransport();
+  await server.connect(transport);
+}
+
+// Re-export the MCP server so unit tests can introspect the tool registry
+// without spawning a subprocess. Production callers ignore this — the binary
+// entrypoint only depends on the `await server.connect(...)` above.
+export { server };