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The repo index agent compresses repository context so subsequent work in the session stays token-efficient. Use it at the start of a session or after substantial codebase changes.

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What this agent does

The repo index agent inspects your repository structure, surfaces recently changed or high-risk files, and generates or updates PROJECT_INDEX.md and PROJECT_INDEX.json when they are stale or missing. Its output is a compact brief that gives Antigravity a precise map of the codebase without requiring a full scan on every query.

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When to invoke

  • At the start of a new development session
  • After a large merge or rebase that changed many files
  • When the agent is referencing wrong file paths or seems to have a stale view of the codebase
  • When PROJECT_INDEX.md is older than 7 days
  • When onboarding to an unfamiliar codebase
Invoking repo index at session start can reduce token usage across the entire session by replacing repeated raw file scans with a single compact index reference.

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How it works

1

Check index freshness

If a PROJECT_INDEX.md exists and is younger than 7 days, the agent confirms this and stops — no regeneration needed.
2

Run parallel searches across five focus areas

If the index is stale or missing, run parallel glob searches across: code, documentation, configuration, tests, and scripts.
3

Generate a compact summary brief

Summarize the results in a data-driven brief, for example:
📦 Summary:
  - Code: src/superclaude (42 files), pm/ (TypeScript agents)
  - Tests: tests/pm_agent, pytest plugin smoke tests
  - Docs: docs/developer-guide, PROJECT_INDEX.md (to be regenerated)
🔄 Next: create PROJECT_INDEX.md (94% token savings vs raw scan)
4

Regenerate the index if needed

If regeneration is required, execute the automated index task using available tools. Output is written to PROJECT_INDEX.md and PROJECT_INDEX.json.

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Core duties

  • Inspect directory structure: src/, tests/, docs/, configuration, scripts
  • Surface recently changed or high-risk files
  • Generate or update PROJECT_INDEX.md and PROJECT_INDEX.json when stale (>7 days) or missing
  • Highlight entry points, service boundaries, and relevant README and ADR docs

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Output format

The agent keeps responses short and data-driven so Antigravity can reference the brief without re-reading the entire repository. The brief is designed to be a session reference, not a report.

Agents overview

How agents work and when to use them.

Deep research

For gathering external information; repo index handles internal codebase context.

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