Fork release: credit fork changes to the build that has them

FORK.md

@@ -84,7 +84,7 @@ check.
   `T3CODE_CLERK_CLI_OAUTH_CLIENT_ID`. Upstream's telemetry tokens are deliberately not copied.
 - The tag sits on the `collin/main` commit. The release notes (`fork/release-notes.sh`) are
   upstream's notes for every nightly since the previous fork build, then the fork's pull
-  requests since then; the update popup shows them. A hidden comment at the end records the fork
+  requests and direct commits since the commit that build built; the update popup shows them. A hidden comment at the end records the fork
   and upstream commits, which the skip check, the watcher and the watchdog read.
 
 ## Keeping changes mergeable

fork/release-notes.sh

@@ -1,11 +1,11 @@
 #!/usr/bin/env bash
 # Release notes of a fork build: the notes of every upstream nightly since the previous fork
-# release, then the fork's own pull requests since then. The app's update popup and the GitHub
-# release page both show this body. A trailing HTML comment, invisible in both, records what was
-# built for fork-release.yml and the watcher.
+# release, then the fork's own changes since the commit that release built. The app's update
+# popup and the GitHub release page both show this body. A trailing HTML comment, invisible in
+# both, records what was built for fork-release.yml and the watcher.
 #
-# Env: REPO (owner/name), TAG (new release tag), TARGET (fork commit), UPSTREAM_TAG,
-# UPSTREAM_SHA, PREVIOUS_TAG (the fork's latest release before this one, may be empty).
+# Env: REPO (owner/name), TARGET (fork commit), UPSTREAM_TAG, UPSTREAM_SHA, PREVIOUS_TAG (the
+# fork's latest release before this one, may be empty).
 set -euo pipefail
 
 # Only the bullet list of a GitHub "What's Changed" body; the app stops reading at
@@ -15,9 +15,11 @@ changes() {
 }
 
 previous_upstream=""
+previous_fork=""
 if [[ -n "$PREVIOUS_TAG" ]]; then
   previous_body=$(gh release view "$PREVIOUS_TAG" --repo "$REPO" --json body --jq .body)
   previous_upstream=$(grep -oE 'upstream-tag=[^ ]+|builds of upstream [^ ]+' <<<"$previous_body" | head -n 1 | sed -E 's/.*[= ]//' || true)
+  previous_fork=$(grep -oE 'fork=[0-9a-f]+|Fork: [0-9a-f]+' <<<"$previous_body" | head -n 1 | sed -E 's/.*[= ]//' || true)
 fi
 
 # Upstream nightlies after the previous build's, up to this build's, oldest first: the app
@@ -33,16 +35,30 @@ for nightly in $nightlies; do
   upstream_changes+=$'\n'
 done
 
+# Between the built commits, not the release tags: a tag lands on the branch head at publish
+# time, which can already hold changes the build did not. First-parent commits of collin/main
+# are its pull request merges, direct commits and upstream syncs; the syncs are left out.
 fork_changes=""
-if [[ -n "$PREVIOUS_TAG" ]]; then
-  fork_changes=$(gh api "repos/$REPO/releases/generate-notes" -f tag_name="$TAG" \
-    -f target_commitish="$TARGET" -f previous_tag_name="$PREVIOUS_TAG" --jq .body | changes)
+if [[ -n "$previous_fork" ]]; then
+  git_dir=$(mktemp -d)
+  git -C "$git_dir" init -q
+  git -C "$git_dir" fetch -q --filter=tree:0 --no-tags "https://github.com/$REPO.git" "$TARGET" "$previous_fork"
+  while read -r commit; do
+    subject=$(git -C "$git_dir" log -1 --format=%s "$commit")
+    if [[ "$subject" =~ ^Merge\ pull\ request\ \#([0-9]+) ]]; then
+      title=$(git -C "$git_dir" log -1 --format=%b "$commit" | head -n 1)
+      fork_changes+="* ${title:-$subject} in https://github.com/$REPO/pull/${BASH_REMATCH[1]}"$'\n'
+    elif [[ $(git -C "$git_dir" rev-list --parents -n 1 "$commit" | wc -w) -eq 2 ]]; then
+      fork_changes+="* $subject"$'\n'
+    fi
+  done < <(git -C "$git_dir" rev-list --first-parent --reverse "$previous_fork..$TARGET")
+  rm -rf "$git_dir"
 fi
 
 if [[ -n "${upstream_changes//[[:space:]]/}" ]]; then
   printf '## T3 Code\n%s\n' "$upstream_changes"
 fi
 if [[ -n "$fork_changes" ]]; then
-  printf '## Fork\n%s\n\n' "$fork_changes"
+  printf '## Fork\n%s\n' "$fork_changes"
 fi
 printf '<!-- fork-release fork=%s upstream=%s upstream-tag=%s -->\n' "$TARGET" "$UPSTREAM_SHA" "$UPSTREAM_TAG"