fix(connector-slack): no construct-time Slack auth (green main)

[harry-harish]

Root cause

SlackAdapter's constructor called new App({ token, appToken, socketMode: true }).
Bolt's App constructor fires a construct-time auth.test() call to api.slack.com to
fetch bot identity. In tests, fake tokens (xoxb-test / xapp-test) make this reject
with invalid_auth. Nothing awaited the rejection, so vitest reported 3 unhandled promise
rejections and failed the process — even though all 7 assertions passed.

Fix

Production fix (preferred over vi.mock): deferInitialization: true

• Added deferInitialization: true to the Bolt App constructor options. This is an
  official Bolt 4.x API that skips the construct-time auth.test() call entirely.
• SlackAdapter.start() now calls await this.app.init() before await this.app.start()
  to run the deferred initialization at the correct moment (Bolt's init() → start()
  sequence when deferInitialization is used).

No mock or test-only shim is needed — the fix is in production code, which also benefits
real integrations where you want to construct the adapter before credentials are verified
(e.g. DI containers, lazy initialization).

New guard test

Added a 'SlackAdapter construction' describe block that:

1. Constructs SlackAdapter with fake tokens and asserts no synchronous throw.
2. Flushes microtasks via await Promise.resolve() to surface any immediate rejection.
3. Asserts the adapter instance is defined.

This test locks in the network-free construction invariant so regressions are caught immediately.

Verification

pnpm --filter @peekdev/connector-slack exec vitest run src/slack-adapter.test.ts
# ✓ 8 tests, 0 unhandled rejections
pnpm build && pnpm typecheck && pnpm lint && pnpm test
# all green (1161+ tests across all packages)

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Improved Slack connector startup so creating the adapter no longer triggers an immediate network call or async rejection.
  • Startup now completes initialization before the connector begins running, making app launch more reliable.
• Tests
  • Added coverage for adapter construction to verify it can be created safely without throwing.

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 42c87b81-3a0a-415c-9f62-40d1a11e6442

📥 Commits

Reviewing files that changed from the base of the PR and between 8947f44 and 33c4b9f.

📒 Files selected for processing (2)

• packages/connector-slack/src/slack-adapter.test.ts
• packages/connector-slack/src/slack-adapter.ts

---

📝 Walkthrough

Walkthrough

SlackAdapter's Bolt App construction now sets deferInitialization: true, and start() explicitly calls app.init() before app.start() to complete deferred initialization. A new test verifies constructing SlackAdapter does not throw synchronously or trigger an immediate unhandled rejection.

Changes

Slack Adapter deferred init

Layer / File(s)	Summary
Deferred initialization and startup sequencing packages/connector-slack/src/slack-adapter.ts	Bolt App is constructed with deferInitialization: true, and start() now awaits app.init() before app.start().
Construction safety test packages/connector-slack/src/slack-adapter.test.ts	New test constructs SlackAdapter with fake tokens and confirms no synchronous throw or immediate unhandled rejection occurs.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Sequence Diagram(s)

sequenceDiagram
    participant Caller
    participant SlackAdapter
    participant BoltApp

    Caller->>SlackAdapter: new SlackAdapter(tokens)
    SlackAdapter->>BoltApp: new App({ deferInitialization: true })
    Note over BoltApp: no auth.test() call yet

    Caller->>SlackAdapter: start()
    SlackAdapter->>BoltApp: await app.init()
    SlackAdapter->>BoltApp: await app.start()

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🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: preventing Slack auth during SlackAdapter construction.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/connector-slack-bolt-defer-init

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[harry-harish]

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