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

[mastermanas805]

Summary

Drives src/ to >=95% line + branch coverage via 161 new unit-level tests across three new/extended files.

Coverage (via dist-test/src/, measured by node --test --experimental-test-coverage)

File	Lines	Branches
src/client.ts	100.00%	95.04%
src/index.ts	99.70%	95.00%
src/name_schema.ts	100.00%	100.00%
All files	99.81%	95.03%

The 3 uncovered lines on src/index.ts (995-997) are the production await server.connect(transport) path — unreachable from unit tests by design (guarded by INSTANODE_MCP_NO_LISTEN).

What the tests cover

• Every InstantClient method (each create_*, listResources, listDeployments, getDeployment, deleteDeployment, claimToken, getApiToken, redeploy) — success + error envelope + AuthRequired
• Every tool handler (create_postgres → delete_deployment) — success path, catch-formatError path, optional-field absent branches
• Every formatError cascade arm — 401, 403/paid_tier_only, 403/PAT (via code + message + name-of-message detection), 429, code+message, no-code, plain Error coercion, non-Error coercion
• Every empty-2xx-body sentinel path — both request<T> and requestMultipart
• Every requireAuth gate — list_resources / get_deployment / delete_* / redeploy / get_api_token without INSTANODE_TOKEN
• Edge cases: empty-string token → AuthRequired; non-Error throw → String(err) branch; mock returns no name → arg fallback; result.dimensions precedence chain; multipart non-OK with empty body vs {} body vs JSON error envelope vs HTML body

Source refactor (minimal, all backward-compatible)

src/index.ts:

• Exports formatError, formatLimits, appendUpgradeBlock, textResult (were module-private; integration tests still exercise them via the spawned subprocess, unchanged)
• Exports the McpServer server instance so unit tests can drive registered tool callbacks in-process via _registeredTools
• Guards the top-level await server.connect(transport) behind INSTANODE_MCP_NO_LISTEN — production binary + integration tests 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

Test counts

• Before: 87 tests (integration only)
• After: 248 tests (87 integration + 161 unit, all passing)

Files

• test/client-unit.test.ts — extended from 25 to 73 tests
• test/index-unit.test.ts — new, 35 tests (pure helper coverage)
• test/tools-unit.test.ts — new, 79 tests (every tool handler)
• src/index.ts — refactor for testability (export helpers + server, guard connect)
• package.json — test script now includes --experimental-test-coverage + the two new files

Test plan

• npm test passes with all 248 tests green
• Coverage report shows src/ >=95% on both lines + branches
• Existing 87 integration tests still pass (verified, untouched)
• Production binary path (node dist/index.js) behavior unchanged (only the unit-test path sets INSTANODE_MCP_NO_LISTEN)

🤖 Generated with Claude Code

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CI fix (2026-05-22)

The build + coverage jobs were failing because the test script uses --test-coverage-exclude (Node 22.5.0+) while both workflows pinned node-version: 20 (errored bad option: --test-coverage-exclude). Bumped both to Node 22 and dropped the || true mask on the coverage job per CLAUDE.md rule 12 (no test-masking).