Add unit tests for 6 low-coverage modules (89 new tests)

[devin-ai-integration]

What Changed

Added 89 new unit tests across 6 test files targeting modules that previously had 0% or very low function/line coverage:

Module	Prev Function Cov	Prev Line Cov	Tests Added
src/subagents/linter.ts	0%	14%	17
src/subagents/audit.ts	0%	2%	9
src/scheduler/human.ts	40%	26%	23
src/agent/prompt-blocks/evolved.ts	0%	0%	14
src/agent/message-param-utils.ts	50%	9%	14
src/chat/storage.ts	41%	44%	12

Why

Coverage analysis revealed these modules had the lowest test coverage in the codebase. All contain pure logic or simple I/O that is straightforward to unit test without external dependencies.

How I Tested

bun test                # 2740 tests pass (89 new), 0 failures
bun run lint            # Clean
bun run typecheck       # Clean

Each new test file also passes independently:

bun test src/subagents/__tests__/linter.test.ts
bun test src/subagents/__tests__/audit.test.ts
bun test src/scheduler/__tests__/human.test.ts
bun test src/agent/prompt-blocks/__tests__/evolved.test.ts
bun test src/agent/__tests__/message-param-utils.test.ts
bun test src/chat/__tests__/storage.test.ts

Checklist

• Tests pass (bun test)
• Lint passes (bun run lint)
• Typecheck passes (bun run typecheck)
• No secrets or .env files included
• Files stay under 300 lines
• No Cardinal Rule violations (TypeScript does plumbing only, the Agent SDK does reasoning)
• No default exports or barrel files added

Link to Devin session: https://app.devin.ai/sessions/83c3044c5f0e4769a1195f4e810df92b
Requested by: @mcheemaa

[devin-ai-integration]

🤖 Devin AI Engineer

I'll be helping with this pull request! Here's what you should know:

✅ I will automatically:

• Address comments on this PR. Add '(aside)' to your comment to have me ignore it.
• Look at CI failures and help fix them

Note: I can only respond to comments from users who have write access to this repository.

⚙️ Control Options:

• Disable automatic comment, CI, and merge conflict monitoring