Fix dead assertion in Slack private-channel audience test

[kapunahelewong]

Problem

The test `"ignores Slack bot and app members when deriving a private-channel audience"` in templates/brain/server/lib/brain.test.ts asserted:

expect(
  mocks.rows.audienceMembers.map((member) => member.principalId),
).toEqual(["ada@example.test"]);

But ./audiences.js is fully mocked at the top of the same test file, and the mocked ensureCaptureAudience never writes to mocks.rows.audienceMembers — it always hardcodes kind: "org" and ignores whatever memberEmails/kind are actually passed in. So the real audience-membership logic in audiences.ts never runs during this test, and mocks.rows.audienceMembers is always []. The assertion could never pass — deterministic, not a flake.

This was blocking PR #2711 (an unrelated docs-only PR) from going green in CI.

Fix

Switched the assertion to the same convention already used by sibling tests in this describe block (e.g. around L2979/L3025/L3031): assert on what the mocked ensureCaptureAudience was actually called with, rather than reading back a mock table the stub never populates.

expect(vi.mocked(ensureCaptureAudience)).toHaveBeenCalledWith(
  expect.objectContaining({
    kind: "slack-private-channel",
    memberEmails: ["ada@example.test"],
    upstreamRefHash: "G123",
  }),
);

This matches what createSlackThreadCapture in connectors.ts actually passes through createCapture → ensureCaptureAudience.

Verification

• Target test passes in isolation.
• Confirmed the test actually catches a regression: temporarily disabled the bot/app-user filter (is_bot/is_app_user/is_workflow_bot/deleted) in connectors.ts, reran, saw it fail, then restored the filter (git diff on connectors.ts shows no residual changes).
• Full brain suite: 282/282 tests passing across 34 files.

Only one file changed — templates/brain/server/lib/brain.test.ts.

🤖 Generated with Claude Code

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Review Details

Code Review Summary

PR #2748 replaces a dead assertion in the Slack private-channel audience test with an assertion against the mocked ensureCaptureAudience call. This aligns the test with the actual mock boundary and verifies the filtered member email, private-channel audience kind, and upstream reference hash that createSlackThreadCapture should pass through.

The approach is sound for this low-risk, test-only change. Two independent reviews found no confirmed correctness, security, or performance issues. The new assertion is materially stronger than reading mocks.rows.audienceMembers, which the fully mocked audience implementation does not populate, and the reported targeted and full-suite verification supports the change. No comments are required.

Risk assessment: Low risk (test-only change).

🧪 Browser testing: Skipped — PR only modifies backend/config/docs, no UI impact