Codebase Q&A

Codebase Q&A answers questions about how the system works, with citations into the index. It is retrieval plus inference, not a chat log of the whole monorepo.

Ask

POST /v1/dev/qa
Authorization: Bearer eridian_sk_...
Content-Type: application/json
Idempotency-Key: qa-payment-flow-2026-09-08

{
  "project_id": "prj_dev_001",
  "repository_ids": ["repo_payments_core", "repo_payments_api"],
  "model": "auto",
  "routing_policy": "quality_optimized",
  "question": "How does the payment flow retry a posting when the ledger returns 503?",
  "filters": {
    "paths": ["src/**", "internal/ledger/**"],
    "languages": ["typescript", "go"]
  },
  "features": ["pii_redaction", "semantic_cache"]
}

Required scope: dev:write for a new question, dev:read to retrieve a prior answer while retention still holds the record.

Response

{
  "id": "qa_19c4",
  "object": "eridian.dev.qa",
  "model": "gemini",
  "answer": "postEntry retries on 503 in posting.ts. The ledger requires an Idempotency-Key on append; the retry path currently omits it.",
  "citations": [
    {
      "repository_id": "repo_payments_core",
      "path": "src/ledger/posting.ts",
      "start_line": 198,
      "end_line": 220,
      "sha": "8f3a2b1c"
    }
  ],
  "eridian": {
    "request_id": "axm_req_qa_19c4",
    "route": "gemini",
    "rag_chunks": 8,
    "cache_hit": false,
    "region": "eu-west-1",
    "cost_usd": 0.012
  }
}

If retrieval finds nothing, Eridian returns HTTP 200 with answer stating that no indexed source supports the question, and citations: []. It does not invent a path. Empty citations with a confident answer is a bug. File it with contact@geteridian.com and the request_id.

Grounding rules

• Answers must cite at least one chunk unless the question is meta (index status, repository list).
• Citations include sha. Stale SHAs mean the index lagged a push. Reindex. See Repositories.
• Cross-repo questions require every id to live in the same region.
• "auto" often selects Gemini for long context, then may not fallback. Pin gpt if your eval showed tighter citations on that desk.

Conversation

Q&A is stateless per request. To continue, send prior_qa_ids:

{
  "question": "Where is that key generated?",
  "prior_qa_ids": ["qa_19c4"]
}

The gateway loads prior questions, not prior model hidden state. Maximum thread length is 12 turns. See Dev Limits.

Python

from eridian import Eridian

client = Eridian(api_key="eridian_sk_...", project_id="prj_dev_001")

result = client.dev.qa.create(
    repository_ids=["repo_payments_core"],
    model="auto",
    question="How does the payment flow retry a posting when the ledger returns 503?",
)
print(result.answer)
for citation in result.citations:
    print(citation.path, citation.start_line, citation.sha)

What not to use it for

• Completions in the editor. Use Code Completion.
• Merge decisions. Use Code Review.
• Secrets. If the question would require a secret file, the index should not contain it.

See RAG Pipeline for the shared retrieval layer and Dev API for list and get.