ci: generate release announcement from diff via a release-note skill

.agents/skills/release-note/SKILL.md

@@ -0,0 +1,71 @@
+---
+name: release-note
+description:
+  Write a user-facing Discord release announcement for the mittwald CLI (command
+  `mw`) from a git commit log and code diff. Trigger when asked to generate,
+  summarize, or write a release note/announcement for a release tag.
+---
+
+# Release note
+
+Write a short, friendly release announcement for the **mittwald CLI** (the `mw`
+command), suitable for posting in a Discord channel aimed at users of the CLI.
+
+## Determining what changed
+
+You are given a release **tag** (e.g. `v1.20.0`). You run inside a full checkout
+of the repository, so all tags and history are available. Collect the commit log
+and the code diff for everything since the previous stable minor/major release
+by running this in the repository root:
+
+```bash
+TAG="<the release tag you were given>"
+
+# All stable minor/major tags (patch == 0), sorted ascending by version.
+MINORS=$(git tag --list 'v*' | grep -E '^v[0-9]+\.[0-9]+\.0$' | sort -V)
+
+# The stable minor tag immediately preceding TAG (empty if TAG is the first one).
+PREV=$(echo "$MINORS" | grep -B1 -x "$TAG" | grep -v -x "$TAG" | tail -1)
+
+# Range to diff: previous minor..current, or just TAG if there is no predecessor.
+if [[ -z "$PREV" ]]; then RANGE="$TAG"; else RANGE="$PREV..$TAG"; fi
+
+# Commit log — for orientation only.
+git log --no-merges --pretty=format:'- %s (%h)' $RANGE > changes.txt
+
+# The actual code diff. Exclude generated docs and lockfiles (they are noise),
+# and cap the size so it stays within the model's context window.
+git diff --stat $RANGE -- \
+  ':(exclude)docs/**' ':(exclude)**/*.lock' \
+  ':(exclude)yarn.lock' ':(exclude)package-lock.json' > diff.txt
+echo "" >> diff.txt
+git diff $RANGE -- \
+  ':(exclude)docs/**' ':(exclude)**/*.lock' \
+  ':(exclude)yarn.lock' ':(exclude)package-lock.json' >> diff.txt
+head -c 200000 diff.txt > diff.trimmed.txt && mv diff.trimmed.txt diff.txt
+```
+
+Then read `changes.txt` and `diff.txt`. **Base the release note on what the diff
+actually changes**, not merely on what the commit subjects claim; use the commit
+log only for orientation / grouping.
+
+## Rules for the note
+
+- Use GitHub-flavored Markdown and a few tasteful emoji.
+- Group related changes into a handful of bullet points; focus on user-facing
+  highlights.
+- Mention affected command names in the form `mw <group> <command>` explicitly,
+  wherever the diff makes them clear.
+- Skip pure dependency bumps, chores and internal refactors unless notable.
+- No preamble and no heading with the version number (a heading is added
+  separately by the publishing step).
+- Keep it under ~1200 characters.
+
+## Output
+
+Write **only** the finished release note to a file named `note.md` in the
+current working directory, using your file-writing tool.
+
+The content of `note.md` is the sole deliverable. Anything you say in the chat
+is discarded, and any stray text in `note.md` will be posted verbatim to
+Discord.

.github/workflows/release-announcement.yml

@@ -46,31 +46,6 @@ jobs:
         with:
           node-version: "24"
 
-      - name: Determine previous minor release and collect changes
-        if: steps.check.outputs.should_run == 'true'
-        id: changes
-        run: |
-          TAG="${{ steps.check.outputs.tag }}"
-
-          # All stable minor/major tags, sorted ascending by version.
-          MINORS=$(git tag --list 'v*' | grep -E '^v[0-9]+\.[0-9]+\.0$' | sort -V)
-
-          # The stable minor tag immediately preceding the current one.
-          PREV=$(echo "$MINORS" | grep -B1 -x "$TAG" | grep -v -x "$TAG" | tail -1)
-
-          if [[ -z "$PREV" ]]; then
-            echo "::notice::No previous minor release found; using full history."
-            RANGE="$TAG"
-          else
-            RANGE="$PREV..$TAG"
-          fi
-          echo "prev=$PREV" >> "$GITHUB_OUTPUT"
-          echo "range=$RANGE" >> "$GITHUB_OUTPUT"
-
-          # Collect the commit log for the range into a file for the model.
-          git log --no-merges --pretty=format:'- %s (%h)' $RANGE > changes.txt
-          echo "Collected $(wc -l < changes.txt) commits for range $RANGE"
-
       - name: Install OpenCode CLI
         if: steps.check.outputs.should_run == 'true'
         run: npm install -g opencode-ai
@@ -93,11 +68,18 @@ jobs:
                   "apiKey": "{env:MITTWALD_AI_API_KEY}"
                 },
                 "models": {
-                  "Ministral-3-14B-Instruct-2512": {
-                    "name": "Ministral-3-14B-Instruct-2512"
+                  "Mistral-Medium-3.5-128B": {
+                    "name": "mistral-medium-3.5"
                   }
                 }
               }
+            },
+            "permission": {
+              "skill": "allow",
+              "read": "allow",
+              "write": "allow",
+              "edit": "allow",
+              "bash": "allow"
             }
           }
           EOF
@@ -109,22 +91,17 @@ jobs:
           MITTWALD_AI_API_KEY: ${{ secrets.MITTWALD_AI_API_KEY }}
         run: |
           TAG="${{ steps.check.outputs.tag }}"
-          PREV="${{ steps.changes.outputs.prev }}"
-
-          PROMPT="You are writing a release announcement for the mittwald CLI (command 'mw').
-          Below is the git commit log for release ${TAG}${PREV:+ (changes since ${PREV})}.
-          Write a short, friendly release note aimed at users, suitable for posting in Discord.
-          Rules:
-          - Use GitHub-flavored Markdown and a few tasteful emoji.
-          - Group related changes into a handful of bullet points; focus on user-facing highlights.
-          - Skip pure dependency bumps, chores and internal refactors unless notable.
-          - No preamble, no heading with the version (that is added separately), max ~1200 characters.
-
-          Commit log:
-          $(cat changes.txt)"
-
-          # 'opencode run' executes a single non-interactive prompt and prints the response.
-          opencode run -m mittwald/Ministral-3-14B-Instruct-2512 "$PROMPT" > note.md
+
+          # Make sure a stale note.md can't leak into the announcement.
+          rm -f note.md
+
+          # 'opencode run' executes a single non-interactive prompt.
+          opencode run -m mittwald/mistral-medium-3.5 "/release-note ${TAG}"
+
+          if [[ ! -s note.md ]]; then
+            echo "::error::OpenCode did not produce a note.md file."
+            exit 1
+          fi
 
           echo "----- Generated note -----"
           cat note.md