diff --git a/.github/workflows/weekly-api-diff.yml b/.github/workflows/weekly-api-diff.yml
index 1c49feb88d6..4c6a4f0e2ed 100644
--- a/.github/workflows/weekly-api-diff.yml
+++ b/.github/workflows/weekly-api-diff.yml
@@ -35,7 +35,7 @@ jobs:
         run: yarn build:api-published
 
       - name: Generate diff
-        run: yarn compare:apis --isCI > /tmp/diff-current.txt || true
+        run: yarn compare:apis --isCI > /tmp/diff-current.md || true
 
       # Check out snapshots repo so we can read the previous diff and commit the new one
       - uses: actions/checkout@v4
@@ -76,12 +76,12 @@ jobs:
 
           if [ "$NEW_RELEASE" != "true" ]; then
             # Compare against the last diff in the snapshots repo
-            PREV=$(ls snapshots/diffs/*.txt 2>/dev/null | sort -r | head -1)
+            PREV=$(ls snapshots/diffs/*.md 2>/dev/null | sort -r | head -1)
             echo ""
             echo "=== Delta computation ==="
             echo "Comparing against: ${PREV:-(none, first run)}"
             if [ -n "$PREV" ]; then
-              diff "$PREV" /tmp/diff-current.txt > /tmp/weekly-delta.txt || true
+              diff "$PREV" /tmp/diff-current.md > /tmp/weekly-delta.txt || true
             else
               echo "(first run — no previous diff to compare against)" > /tmp/weekly-delta.txt
             fi
@@ -89,7 +89,7 @@ jobs:
 
           echo ""
           echo "=== File sizes ==="
-          echo "diff-current.txt: $(wc -c < /tmp/diff-current.txt) bytes"
+          echo "diff-current.md: $(wc -c < /tmp/diff-current.md) bytes"
           ls /tmp/weekly-delta.txt 2>/dev/null && echo "weekly-delta.txt: $(wc -c < /tmp/weekly-delta.txt) bytes" || echo "weekly-delta.txt: not created"
           echo ""
           echo "=== Delta content (first 20 lines) ==="
@@ -99,9 +99,9 @@ jobs:
           # Skip if no difference from last diff (aka no change from last week/last run), or if the diff against the release code is empty
           echo ""
           echo "=== Commit decision ==="
-          if [ -s /tmp/diff-current.txt ] && ([ "$NEW_RELEASE" = "true" ] || [ -s /tmp/weekly-delta.txt ]); then
+          if [ -s /tmp/diff-current.md ] && ([ "$NEW_RELEASE" = "true" ] || [ -s /tmp/weekly-delta.txt ]); then
             echo "Committing diff to snapshots repo"
-            cp /tmp/diff-current.txt snapshots/diffs/$TODAY.txt
+            cp /tmp/diff-current.md snapshots/diffs/$TODAY.md
             mkdir -p snapshots/deltas
             if [ -s /tmp/weekly-delta.txt ]; then
               # Save processed delta: strip > / < markers and line-number markers,
@@ -115,20 +115,20 @@ jobs:
                   echo "=== API CHANGES RELEASED SINCE LAST WEEK (were in last week's diff, now gone) ==="
                   echo "$RELEASED"
                 fi
-              } > snapshots/deltas/$TODAY.txt
+              } > snapshots/deltas/$TODAY.md
             fi
             cd snapshots
             git config user.email "github-actions@github.com"
             git config user.name "GitHub Actions"
-            git add diffs/$TODAY.txt
-            [ -f deltas/$TODAY.txt ] && git add deltas/$TODAY.txt
+            git add diffs/$TODAY.md
+            [ -f deltas/$TODAY.md ] && git add deltas/$TODAY.md
             echo "$CURRENT_PUBLISH" > last-publish-hash.txt
             git add last-publish-hash.txt
             echo "=== Staged changes ==="
             git diff --cached --stat
             git diff --cached --quiet || (git commit -m "weekly api diff $TODAY" && git push)
           else
-            echo "Skipping commit — diff-current empty=$([ ! -s /tmp/diff-current.txt ] && echo yes || echo no), new_release=$NEW_RELEASE, delta_empty=$([ ! -s /tmp/weekly-delta.txt ] && echo yes || echo no)"
+            echo "Skipping commit — diff-current empty=$([ ! -s /tmp/diff-current.md ] && echo yes || echo no), new_release=$NEW_RELEASE, delta_empty=$([ ! -s /tmp/weekly-delta.txt ] && echo yes || echo no)"
           fi
 
       # Summarize with GitHub Models (free via GITHUB_TOKEN) and post to Slack
@@ -136,6 +136,7 @@ jobs:
         env:
           SLACK_TSDIFF_CHROMATIC_BOT_TOKEN: ${{ secrets.SLACK_TSDIFF_CHROMATIC_BOT_TOKEN }}
           SLACK_CHANNEL_ID: ${{ secrets.SLACK_CHANNEL_ID }}
+          TEST_SLACK_ID: ${{ secrets.TEST_SLACK_ID }}
           GITHUB_TOKEN: ${{ github.token }}
         run: |
           python3 << 'PYEOF'
@@ -152,15 +153,15 @@ jobs:
           slack_token = os.environ['SLACK_TSDIFF_CHROMATIC_BOT_TOKEN']
           github_token = os.environ['GITHUB_TOKEN']
           workspace = os.environ['GITHUB_WORKSPACE']
-          diff_url = f"https://github.com/{snapshots_repo}/blob/main/diffs/{today}.txt"
-          delta_url = f"https://github.com/{snapshots_repo}/blob/main/deltas/{today}.txt"
+          diff_url = f"https://github.com/{snapshots_repo}/blob/main/diffs/{today}.md"
+          delta_url = f"https://github.com/{snapshots_repo}/blob/main/deltas/{today}.md"
 
-          vs_release_size = os.path.getsize('/tmp/diff-current.txt')
+          vs_release_size = os.path.getsize('/tmp/diff-current.md')
           vs_last_week_size = os.path.getsize('/tmp/weekly-delta.txt') if os.path.exists('/tmp/weekly-delta.txt') else 0
 
-          prev_files = sorted(glob.glob(f"{workspace}/snapshots/diffs/*.txt"), reverse=True)
-          prev_date = os.path.basename(prev_files[0]).replace('.txt', '') if prev_files else None
-          prev_url = f"https://github.com/{snapshots_repo}/blob/main/diffs/{prev_date}.txt" if prev_date else None
+          prev_files = sorted(glob.glob(f"{workspace}/snapshots/diffs/*.md"), reverse=True)
+          prev_date = os.path.basename(prev_files[0]).replace('.md', '') if prev_files else None
+          prev_url = f"https://github.com/{snapshots_repo}/blob/main/diffs/{prev_date}.md" if prev_date else None
 
           new_release = os.environ.get('NEW_RELEASE') == 'true'
 
@@ -191,7 +192,7 @@ jobs:
             body = f"New release since last diff — resetting baseline. Full diff vs release: {diff_url}\n\nReact ✅ if changes look expected, or 🚨 if something looks wrong."
           else:
             # Read the already-processed delta saved by the shell step
-            delta_path = f"{workspace}/snapshots/deltas/{today}.txt"
+            delta_path = f"{workspace}/snapshots/deltas/{today}.md"
             model_input_full = open(delta_path).read() if os.path.exists(delta_path) else ""
             TRUNCATE_LIMIT = 8000
             truncated = len(model_input_full) > TRUNCATE_LIMIT
diff --git a/scripts/buildBranchAPI.js b/scripts/buildBranchAPI.js
index b663c368cd3..954d338db58 100644
--- a/scripts/buildBranchAPI.js
+++ b/scripts/buildBranchAPI.js
@@ -163,6 +163,23 @@ async function build() {
     recursive: true
   });
 
+  // Collect workspace package names so we can strip intra-monorepo dependencies.
+  // Sibling packages may pin exact versions (e.g. "@adobe/react-spectrum": "3.47.0")
+  // that don't match the workspace version being built, causing yarn to install from
+  // npm instead of symlinking to the workspace. Removing these entries lets yarn always
+  // resolve them via the workspace.
+  let workspacePackageNames = new Set(
+    packages
+      .map(p => {
+        try {
+          return JSON.parse(fs.readFileSync(path.join(srcDir, 'packages', p), 'utf8')).name;
+        } catch {
+          return null;
+        }
+      })
+      .filter(Boolean)
+  );
+
   let excludeList = ['@react-spectrum/story-utils'];
   // Copy packages over to temp dir
   console.log('copying over');
@@ -186,6 +203,13 @@ async function build() {
       delete json.main;
       delete json.module;
       delete json.devDependencies;
+      if (json.dependencies) {
+        for (let dep of Object.keys(json.dependencies)) {
+          if (workspacePackageNames.has(dep)) {
+            delete json.dependencies[dep];
+          }
+        }
+      }
       json.apiCheck = 'dist/api.json';
       json.targets = {
         apiCheck: {}