qgs-ai-summary.yml

name: qgs-ai-summary

# Post a concise, human-readable summary of the real changes to QGIS .qgs
# project files on a PR. scripts/qgs-diff.py builds a churn-free diff of the
# changed files; the GitHub Copilot CLI turns it into per-file bullet points;
# the result is posted as a single self-updating PR comment. Nothing derived
# is committed.

on:
  pull_request:
    paths:
      - '**/*.qgs'

permissions:
  contents: read
  pull-requests: write
  copilot-requests: write
concurrency:
  group: qgs-ai-summary-${{ github.event.pull_request.number }}
  cancel-in-progress: true

jobs:
  summarise:
    runs-on: ubuntu-latest
    env:
      MODEL: gpt-5.4
    steps:
      - uses: actions/checkout@v4
        with:
          ref: ${{ github.event.pull_request.head.sha }}
          fetch-depth: 0

      - name: Build churn-free diff
        id: diff
        run: |
          WORK="$RUNNER_TEMP/qgs-ai"
          mkdir -p "$WORK"
          python3 scripts/qgs-diff.py diff --base "${{ github.base_ref }}" > "$WORK/diff.txt"
          [ -s "$WORK/diff.txt" ] && echo "changed=1" >> "$GITHUB_OUTPUT" || echo "changed=0" >> "$GITHUB_OUTPUT"

      - name: Set up Node for the Copilot CLI
        if: steps.diff.outputs.changed == '1'
        uses: actions/setup-node@v4
        with:
          node-version: 24

      - name: Install Copilot CLI
        if: steps.diff.outputs.changed == '1'
        run: npm install -g @github/copilot

      - name: Summarise with the Copilot CLI
        id: ai
        if: steps.diff.outputs.changed == '1'
        env:
          # Built-in workflow token — the Copilot CLI authenticates from this
          # (via the copilot-requests permission), so no PAT/secret is needed.
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          set -euo pipefail
          WORK="$RUNNER_TEMP/qgs-ai"
          cd "$WORK"
          echo "::group::diff (contains $(wc -l < diff.txt) lines, $(wc -c < diff.txt) bytes)"
          cat diff.txt
          echo
          echo "::endgroup::"

          # Cap the inlined diff. Linux limits a single argv string to ~128 KB
          # (MAX_ARG_STRLEN), so the whole -p argument (prompt + diff) must stay
          # under that or copilot dies with "Argument list too long". The
          # churn-free diff is normally well under this; only a wholesale rewrite
          # truncates. Override with INPUT_CHAR_BUDGET.
          BUDGET="${INPUT_CHAR_BUDGET:-110000}"
          DIFF="$(head -c "$BUDGET" diff.txt)"
          if [ "$(wc -c < diff.txt)" -gt "$BUDGET" ]; then
            DIFF="$(printf '%s\n[...diff truncated to %s chars to fit the arg limit; summary is partial...]' "$DIFF" "$BUDGET")"
          fi

          echo "::group::Generating summary with Copilot CLI (model $MODEL)"
          # One-shot: the diff is INLINE (not a file to read) and the answer comes
          # back on stdout via -s. This sidesteps the agent read/write loop -- with
          # nothing to read and nothing to write, a large tool-result can't get
          # evicted and trigger endless re-reads; it's a single completion.
          PROMPT="$(printf '%s\n\n--- BEGIN CHURN-FREE DIFF ---\n%s\n--- END CHURN-FREE DIFF ---\n\n%s' \
            "$(cat "$GITHUB_WORKSPACE/scripts/assets/qgs-review-prompt.md")" \
            "$DIFF" \
            'The complete churn-free diff is included above. Do NOT read or write any files. Output ONLY the markdown summary (no preamble or conclusion).')"
          copilot \
            --model "$MODEL" \
            --allow-all-tools \
            --no-ask-user \
            --max-ai-credits 50 \
            -s \
            -p "$PROMPT" > summary.md || true
          cp summary.md "$GITHUB_WORKSPACE/summary.md" 2>/dev/null || true
          echo
          echo "::endgroup::"

      - name: Post sticky PR comment
        env:
          GH_TOKEN: ${{ github.token }}
          REPO: ${{ github.repository }}
          PR: ${{ github.event.pull_request.number }}
          CHANGED: ${{ steps.diff.outputs.changed }}
          MODEL: ${{ env.MODEL }}
        run: |
          set -euo pipefail
          MARKER='<!-- qgs-ai-summary -->'
          {
            echo "$MARKER"
            echo "## 🗺️ QGIS project change summary"
            echo
            if [ "$CHANGED" = "1" ] && [ -s summary.md ]; then
              cat summary.md
              echo
              echo "<sub>Generated by \`$MODEL\` via the GitHub Copilot CLI from a churn-free diff - verify against the file diff.</sub>"
            else
              echo "_No substantive QGIS project changes detected - only QGIS session churn._"
            fi
          } > comment.md

          id=$(gh api "repos/$REPO/issues/$PR/comments" --paginate \
                 --jq ".[] | select(.body | contains(\"$MARKER\")) | .id" | head -n1)
          if [ -n "$id" ]; then
            gh api -X PATCH "repos/$REPO/issues/comments/$id" -F body=@comment.md >/dev/null
            echo "updated comment $id"
          else
            gh api -X POST "repos/$REPO/issues/$PR/comments" -F body=@comment.md >/dev/null
            echo "created comment"
          fi