Produce the comment text within the main PR CI workflow to ensure comment and CI always match

Author: Gedochao

.github/scripts/build-pr-classification-comment.sc

@@ -13,16 +13,17 @@
 
 // Builds the Markdown body for the PR sticky comment that summarizes how the
 // `changes` job classified the diff and which suite groups will run / be
-// skipped.
+// skipped. Intended to be invoked from `ci.yml`'s `changes` job so the
+// resulting comment reflects the exact classification CI is using; the
+// `pr-classify-comment.yml` workflow then downloads the rendered body as
+// an artifact and posts it as a sticky PR comment.
 //
 // Inputs (env vars):
 //   CLASSIFY_OUTPUT_FILE  - KEY=VALUE file produced by classify-changes.sc.
 //   OVERRIDE_OUTPUT_FILE  - KEY=VALUE file produced by check-override-keywords.sc.
 //   COMMENT_OUTPUT_FILE   - Path to write the rendered Markdown to (default: comment.md).
-//   CLASSIFY_RUN_ID       - Run ID of the classification workflow (optional).
-//   CLASSIFY_RUN_URL      - URL to the classification workflow run (optional).
-//   CI_RUN_ID             - Run ID of the matching CI workflow run (optional).
-//   CI_RUN_URL            - URL to the matching CI workflow run, or a fallback.
+//   CI_RUN_ID             - Run ID of the CI workflow run (optional).
+//   CI_RUN_URL            - URL to the CI workflow run (optional).
 
 import prclassify.*
 
@@ -39,8 +40,6 @@ def overrideContributions(signals: Signals): Seq[(OverrideKey, Seq[SuiteGroup])]
 
 def renderComment(
   signals: Signals,
-  classifyRunId: Option[String],
-  classifyRunUrl: Option[String],
   ciRunId: Option[String],
   ciRunUrl: Option[String]
 ): String =
@@ -87,17 +86,8 @@ def renderComment(
     case Some(id) => Some(s"Full CI run: [#$id](${ciRunUrl.getOrElse("")})")
     case None     => ciRunUrl.map(url => s"Full CI run: $url")
 
-  val classifySection: Option[String] = classifyRunId.map: id =>
-    s"_Classified in run [#$id](${classifyRunUrl.getOrElse("")})._"
-
   val sections =
-    Seq(
-      Some(headerSection),
-      Some(suitesSection),
-      overridesSection,
-      ciRunSection,
-      classifySection
-    ).flatten
+    Seq(Some(headerSection), Some(suitesSection), overridesSection, ciRunSection).flatten
 
   sections.mkString("\n\n") + "\n"
 
@@ -111,11 +101,15 @@ val commentPath = Env.toAbsolutePath(
 
 val body = renderComment(
   signals,
-  classifyRunId = Env.opt(EnvNames.ClassifyRunId),
-  classifyRunUrl = Env.opt(EnvNames.ClassifyRunUrl),
   ciRunId = Env.opt(EnvNames.CiRunId),
   ciRunUrl = Env.opt(EnvNames.CiRunUrl)
 )
+println(
+  """Generated comment body:
+    |-----------------------
+    |$body
+    |-----------------------""".stripMargin
+)
 
 os.write.over(commentPath, body, createFolders = true)
 println(s"Wrote comment to $commentPath")

.github/scripts/fetch-pr-changed-files.sc

@@ -5,7 +5,7 @@ package prclassify
   */
 object EnvNames:
 
-  // ---- Inputs ----
+  // ---- Inputs to classify-changes.sc / check-override-keywords.sc ----
   /** "pull_request", "push", ... */
   val EventName = "EVENT_NAME"
 
@@ -20,15 +20,7 @@ object EnvNames:
   /** Body of the pull request (scanned for override markers). */
   val PrBody = "PR_BODY"
 
-  /** "owner/repo". */
-  val Repo     = "REPO"
-  val PrNumber = "PR_NUMBER"
-  val HeadSha  = "HEAD_SHA"
-
-  /** e.g. "https://github.com". */
-  val ServerUrl = "SERVER_URL"
-
-  // ---- Outputs (file-based) ----
+  // ---- KEY=VALUE / comment artifact paths ----
   /** Path where `classify-changes` writes its KEY=VALUE output. */
   val ClassifyOutputFile = "CLASSIFY_OUTPUT_FILE"
 
@@ -39,22 +31,9 @@ object EnvNames:
     */
   val CommentOutputFile = "COMMENT_OUTPUT_FILE"
 
-  // ---- Run-link context ----
-  val ClassifyRunId  = "CLASSIFY_RUN_ID"
-  val ClassifyRunUrl = "CLASSIFY_RUN_URL"
-  val CiRunId        = "CI_RUN_ID"
-  val CiRunUrl       = "CI_RUN_URL"
-
-  // ---- Script tunables ----
-  /** Name of the workflow to search for when resolving the CI run link. */
-  val WorkflowName = "WORKFLOW_NAME"
-  val MaxAttempts  = "MAX_ATTEMPTS"
-  val RetryDelayMs = "RETRY_DELAY_MS"
-  val RunIdOutput  = "RUN_ID_OUTPUT"
-  val RunUrlOutput = "RUN_URL_OUTPUT"
-
-  /** Name of the GITHUB_OUTPUT key `fetch-pr-changed-files` writes to. */
-  val OutputName = "OUTPUT_NAME"
+  // ---- CI run context (embedded in the rendered comment) ----
+  val CiRunId  = "CI_RUN_ID"
+  val CiRunUrl = "CI_RUN_URL"
 
   // ---- GitHub Actions built-ins ----
   val GitHubOutput      = "GITHUB_OUTPUT"

.github/scripts/pr-classify-lib/EnvNames.scala

@@ -0,0 +1,63 @@
+#!/usr/bin/env bash
+# Polls the GitHub REST API until the `changes` job of the CI workflow run
+# matching $HEAD_SHA has finished. Exits 0 on success (and writes the run id
+# to $GITHUB_OUTPUT as `run_id`), non-zero on failure or timeout.
+#
+# Expected environment variables:
+#   GH_TOKEN          - token used by `gh api`.
+#   REPO              - "owner/name" of the repository.
+#   HEAD_SHA          - PR head SHA to match CI runs against.
+#   GITHUB_OUTPUT     - standard GitHub Actions output file.
+#   MAX_ATTEMPTS      - (optional, default 40) number of polling attempts.
+#   INTERVAL_SECONDS  - (optional, default 15) seconds between attempts.
+#   CI_WORKFLOW_NAME  - (optional, default "CI") name of the workflow to wait for.
+#   CI_JOB_NAME       - (optional, default "changes") name of the job to wait for.
+set -euo pipefail
+
+: "${GH_TOKEN:?GH_TOKEN is required}"
+: "${REPO:?REPO is required}"
+: "${HEAD_SHA:?HEAD_SHA is required}"
+: "${GITHUB_OUTPUT:?GITHUB_OUTPUT is required}"
+
+max_attempts="${MAX_ATTEMPTS:-40}"
+interval="${INTERVAL_SECONDS:-15}"
+workflow_name="${CI_WORKFLOW_NAME:-CI}"
+job_name="${CI_JOB_NAME:-changes}"
+
+attempt=0
+while [ "$attempt" -lt "$max_attempts" ]; do
+  attempt=$((attempt + 1))
+
+  # Find the most recent matching workflow run for this head SHA. The run
+  # may not be discoverable for a few seconds after the PR event dispatches.
+  run_id=$(gh api \
+    "repos/$REPO/actions/runs?event=pull_request&head_sha=$HEAD_SHA&per_page=30" \
+    --jq "[.workflow_runs[] | select(.name==\"$workflow_name\")] | sort_by(.run_number) | last | .id // empty")
+
+  if [ -z "$run_id" ]; then
+    echo "$workflow_name run not yet discoverable for $HEAD_SHA (attempt $attempt/$max_attempts)"
+    sleep "$interval"
+    continue
+  fi
+
+  job=$(gh api "repos/$REPO/actions/runs/$run_id/jobs" \
+    --jq ".jobs[] | select(.name==\"$job_name\") | {status: .status, conclusion: .conclusion}")
+  status=$(echo "$job" | jq -r '.status // empty')
+  conclusion=$(echo "$job" | jq -r '.conclusion // empty')
+
+  if [ "$status" = "completed" ]; then
+    if [ "$conclusion" = "success" ]; then
+      echo "$job_name job completed in $workflow_name run $run_id"
+      echo "run_id=$run_id" >> "$GITHUB_OUTPUT"
+      exit 0
+    fi
+    echo "::error::$job_name job in $workflow_name run $run_id finished with conclusion=$conclusion"
+    exit 1
+  fi
+
+  echo "$workflow_name run $run_id, $job_name job status=$status (attempt $attempt/$max_attempts)"
+  sleep "$interval"
+done
+
+echo "::error::Timed out after $max_attempts attempts waiting for the $job_name job in $workflow_name"
+exit 1

.github/scripts/resolve-ci-run-link.sc

@@ -42,13 +42,35 @@ jobs:
       env:
         EVENT_NAME: ${{ github.event_name }}
         BASE_REF: ${{ github.event.pull_request.base.ref }}
+        CLASSIFY_OUTPUT_FILE: ${{ runner.temp }}/classify.env
       run: .github/scripts/classify-changes.sc
     - name: Check override keywords
       id: overrides
       env:
         EVENT_NAME: ${{ github.event_name }}
         PR_BODY: ${{ github.event.pull_request.body }}
+        OVERRIDE_OUTPUT_FILE: ${{ runner.temp }}/overrides.env
       run: .github/scripts/check-override-keywords.sc
+    # Build the sticky-comment body inside the CI run itself so the comment
+    # posted by pr-classify-comment.yml reflects the exact classification
+    # this CI run is using. The artifact is consumed by pr-classify-comment.yml.
+    - name: Build PR classification comment
+      if: github.event_name == 'pull_request'
+      env:
+        CLASSIFY_OUTPUT_FILE: ${{ runner.temp }}/classify.env
+        OVERRIDE_OUTPUT_FILE: ${{ runner.temp }}/overrides.env
+        COMMENT_OUTPUT_FILE: ${{ runner.temp }}/pr-classification-comment.md
+        CI_RUN_ID: ${{ github.run_id }}
+        CI_RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+      run: .github/scripts/build-pr-classification-comment.sc
+    - name: Upload PR classification comment artifact
+      if: github.event_name == 'pull_request'
+      uses: actions/upload-artifact@v7
+      with:
+        name: pr-classification-comment
+        path: ${{ runner.temp }}/pr-classification-comment.md
+        if-no-files-found: error
+        retention-days: 1
 
   unit-tests:
     needs: [changes]