feat(agent-core): refine system prompt context

[RealKai42]

Related Issue

No linked issue. This PR polishes the system prompt context based on direct prompt-review feedback.

Problem

The default system prompt spent tokens on hidden directory contents and a long AGENTS.md explanation, while dynamic prompt context was mixed into the surrounding guidance. It also gave no signal when AGENTS.md files were truncated by the prompt budget.

What changed

• Collapse hidden directories in the workspace directory snapshot while keeping the top-level entries visible.
• Add prompt guidance for inspecting hidden paths with Glob, Read, and Grep.
• Compress the AGENTS.md prompt guidance and move dynamic AGENTS/skill context after the static rules.
• Add a marker when AGENTS.md content is truncated or omitted because of the prompt budget.
• Cover the new behavior with focused prompt/profile tests.

Checklist

• I have read the CONTRIBUTING document.
• I have linked a related issue, or explained the problem above.
• I have added tests that prove my feature works.
• Ran gen-changesets skill, or this PR needs no changeset.
• Ran gen-docs skill, or this PR needs no doc update.

Tests run:

pnpm --filter @moonshot-ai/agent-core exec vitest run test/tools/list-directory.test.ts test/profile/context.test.ts test/profile/default-agent-profiles.test.ts test/prompt-placeholders.test.ts test/session/subagent-host.test.ts
pnpm --filter @moonshot-ai/agent-core typecheck
pnpm exec oxlint packages/agent-core/src/tools/support/list-directory.ts packages/agent-core/src/profile/context.ts packages/agent-core/test/tools/list-directory.test.ts packages/agent-core/test/session/subagent-host.test.ts packages/agent-core/test/profile/context.test.ts packages/agent-core/test/profile/default-agent-profiles.test.ts

[changeset-bot]

🦋 Changeset detected

Latest commit: 3458ed7

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@moonshot-ai/agent-core	Patch
@moonshot-ai/kimi-code	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[pkg-pr-new]

pnpm dlx https://pkg.pr.new/@moonshot-ai/kimi-code@3458ed7

npx https://pkg.pr.new/@moonshot-ai/kimi-code@3458ed7

commit: 3458ed7