PR Review Flow

# app/api/v1/webhooks.py
@router.post("/github")
async def handle_github_webhook(request: Request, db: AsyncSession):
    # Verify HMAC-SHA256 signature
    signature = request.headers.get("X-Hub-Signature-256")
    if not verify_signature(payload, signature, webhook_secret):
        raise HTTPException(status_code=403, detail="Invalid signature")
    
    # Deduplicate within 1 hour
    existing = await check_duplicate_event(db, delivery_id, within_hours=1)
    if existing:
        return {"status": "duplicate", "event_id": existing.id}
    
    # Create Event record
    event = Event(delivery_id=delivery_id, status="pending")
    db.add(event)
    await db.commit()
    
    # Process in background
    background_tasks.add_task(process_pr_in_background, payload, event.id)
    return {"status": "accepted", "event_id": event.id}

# app/services/pr_review_service.py:496-499
diff = await github_client.get_pr_diff(owner, repo, pr_number, token=github_token)
files = await github_client.get_pr_files(owner, repo, pr_number, token=github_token)
file_paths = [f.get("filename", "") for f in files if f.get("filename")]
author = (pr.get("user") or {}).get("login", "")

# app/services/pr_review_service.py:512-523
issue_details, open_pr_conflicts, candidate_issues, related_prs = await asyncio.gather(
    _fetch_issue_details(owner, repo, issue_refs),
    _get_open_pr_conflicts(owner, repo, pr_number, file_paths),
    _find_candidate_issues(
        owner, repo,
        pr_title, pr_body,
        file_paths,
        already_referenced=set(issue_refs),
    ),
    graph_builder.get_related_prs(repo_full_name, file_paths[:10], top_k=5),
    return_exceptions=True,
)

# app/services/pr_review_service.py:566-569
review_result = await ai_service.analyze_pull_request_agentic(
    pr, diff, files, tool_executor, issue_refs=issue_refs
)

for round_num in range(max_rounds):
    response = await self.client.messages.create(
        model=self.model,
        max_tokens=4000,
        tools=REVIEW_TOOLS,
        messages=messages,
    )
    
    if response.stop_reason == "tool_use":
        for block in response.content:
            if block.type == "tool_use":
                result = await tool_executor.execute(block.name, block.input)
                tool_results.append({
                    "type": "tool_result",
                    "tool_use_id": block.id,
                    "content": result,
                })
        messages.append({"role": "user", "content": tool_results})

# app/services/pr_review_service.py:560-564
use_parallel = getattr(settings, 'PARALLEL_REVIEW_AGENTS', False)
if use_parallel:
    review_result = await ai_service.analyze_pull_request_parallel(
        pr, diff, files, tool_executor, issue_refs=issue_refs
    )

# app/services/ai_service.py:770-773
security_out, performance_out, style_out = await asyncio.gather(
    security_task, performance_task, style_task,
    return_exceptions=True
)

# app/services/ai_service.py:787-795
return await self._synthesize_review(
    pr=pr,
    diff=diff,
    files=files,
    security_findings=security_findings,
    performance_findings=performance_findings,
    style_findings=style_findings,
    issue_refs=issue_refs,
)

# app/services/pr_review_service.py:716-725
try:
    await github_client.post_pr_review(
        owner, repo, pr_number,
        commit_id=head_sha,
        body=comment_body,
        event=github_event,  # "APPROVE" | "REQUEST_CHANGES" | "COMMENT"
        comments=inline_comments,
        token=github_token,
    )
except Exception as review_err:
    # Fallback to flat comment if review fails
    await github_client.post_pr_comment(owner, repo, pr_number, comment_body, token=github_token)

# app/services/pr_review_service.py:771-779
await graph_builder.index_pr(
    repo_full_name=repo_full_name,
    pr_number=pr_number,
    title=pr_title,
    author=author,
    files_changed=file_paths,
    verdict=review_result.verdict,
    issue_numbers=all_issue_numbers,
)

# app/services/pr_review_service.py:782-789
await extract_and_store(
    repo_full_name=repo_full_name,
    pr_number=pr_number,
    author=author,
    title=pr_title,
    files=files,
    review_summary=summary,
)

# app/services/pr_review_service.py:745-756
workflow.status = "completed"
workflow.result = json.dumps({
    "ai_summary": summary,
    "files_analyzed": len(files),
    "comment_posted": True,
    "verdict": review_result.verdict,
    "inline_suggestions": len(inline_comments),
    "linked_issues": [i["number"] for i in linked_issues],
    "related_prs": len(related_prs),
    "open_pr_conflicts": len(open_pr_conflicts),
    "semantic_issue_matches": [m["number"] for m in review_result.semantic_issue_matches],
})