Feature/stacked prs

[desireddymohithreddy0925]

Closes #818

Description

This PR implements the core database schema additions required for the Stacked PRs / Dependent PR Chaining feature.

Changes Made

• Added base_branch and head_branch columns to the pullRequests table in src/lib/db/schema.ts.

Next Steps

By tracking the base and head branches of all synchronized PRs, the backend webhook handlers can now automatically calculate parent-child relationships (e.g. if PR B has a base branch that matches PR A's head branch, it is a dependent PR).

Future PRs will use this data layer to render the Mermaid.js / React Flow dependency graph on the frontend PR view and implement the backend merge-block logic.

Screenshots / UI Thoughts

Schema changes only. The visual graph implementation will follow in a subsequent PR.

[vercel]

Someone is attempting to deploy a commit to the codersogs-3057's projects Team on Vercel.

A member of the Team first needs to authorize it.

[jakharmonika364]

Three spots, assuming the branch gets rebased onto clean main first (drop the carried-over mergeFreezeWindows commit):

1. Rebase (do this first, not a code edit)

git fetch origin main
git rebase origin/main feature/stacked-prs

This drops the duplicate feat: implement database schema merge freeze windows (#819) commit so the diff only shows the base_branch/head_branch change.

---

2. src/lib/db/schema.ts - pullRequests table, line ~446 (the (t) => ({...}) index block)

Add a repo-scoped index next to the existing ones:

(t) => ({
  uniqRepoNumber: uniqueIndex('pull_requests_repo_number_unique').on(t.repoFullName, t.number),
  repoStateIdx: index('pull_requests_repo_state_idx').on(
    t.repoFullName,
    t.state,
    t.githubUpdatedAt,
  ),
  authorIdx: index('pull_requests_author_idx').on(t.authorUserId, t.state),
  repoHeadBranchIdx: index('pull_requests_repo_head_branch_idx').on(
    t.repoFullName,
    t.headBranch,
  ),
}),

---

3. New file supabase/migrations/0044_pull_requests_branch_tracking.sql (next number after 0043_activity_log_read_at.sql - coordinate with #824 so they don't collide on the same number):

alter table pull_requests
add column base_branch text,
add column head_branch text;

create index pull_requests_repo_head_branch_idx on pull_requests(repo_full_name, head_branch);

That's it - pull_requests already has RLS/policies from prior migrations, so no new policy needed here, just the column + index.