docs: relax single-commit rule, add fork baseline to FORK.md

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: dtoms

CLAUDE.md

@@ -4,16 +4,13 @@ Read @FORK.md for full context on this fork.
 
 ## Branch & Commit Strategy
 
-- `af-main` is the fork branch. It must always be exactly **one commit** ahead of upstream.
-- That commit has the subject line: `feat: AppFolio spec-kit fork — specify-af-cli with bundled extensions`. Use this to identify it.
-- When merging work into `af-main` (directly or via squash merge), amend into this single fork commit rather than adding new commits.
+- `af-main` is the fork branch. It accumulates commits from PRs and releases.
 - On feature branches, squash to one commit before merge.
-- Before integrating an upstream release, ensure af-main is one commit ahead, then merge the upstream tag. Resolve conflicts per @FORK.md.
+- Before integrating an upstream release, squash all af-main commits since the fork baseline (see @FORK.md) into one commit, then merge the upstream tag. Resolve conflicts per @FORK.md.
 - Use Conventional Commits on feature branches: `feat:`, `fix:`, `chore:`, etc.
 
 ## Git Rules (enforced by Claude unless user explicitly overrides)
 
-- **Never create additional commits on `af-main`** — always amend the single fork commit.
 - **Always work on a feature branch.** Never commit directly to `af-main` without user confirmation.
 - **Never push merge commits.** If a pull or merge introduces a merge commit, rebase instead.
 - **Before force-pushing `af-main`:** confirm with the user first — this rewrites shared history.

FORK.md

@@ -25,6 +25,18 @@ When merging upstream releases, expect conflicts in these files:
 - `extensions/catalog.json` — keep AF entries and catalog URL
 - `.github/workflows/release.yml` — keep `af-v*` tag filter, AF install URL, extension ZIP step
 
+## Fork Baseline
+
+The fork diverged from upstream at commit `43cb0fa` (`feat: add bundled lean preset with minimal workflow commands (#2161)`).
+The first AF modification is `f44666a` (`feat: AppFolio spec-kit fork — specify-af-cli with bundled extensions`).
+
+When integrating an upstream release:
+1. Squash all af-main commits since `43cb0fa` into one
+2. Merge the upstream tag on top
+3. Update the baseline commit below after resolving conflicts
+
+**Current baseline**: `43cb0fa` — `feat: add bundled lean preset with minimal workflow commands (#2161)`
+
 ## How to Maintain
 
 ### Local Development Setup