Fix ai-labeler.yml YAML syntax error (#146)

* Add shared splice-prompt.py script

Extract the repeated inline Python logic that splices a user message
into a prompt YAML's messages array. Three jobs in ai-labeler.yml
duplicated this identically — pull it into a standalone script that
takes the prompt template path and output path as arguments.

* Fix ai-labeler.yml YAML syntax error

The three inline python3 -c blocks had their code body at column 0,
breaking out of the run: | block scalar and failing GitHub's YAML
validation. Replace each with a one-liner call to the new shared
splice-prompt.py script.

* Fix shellcheck SC2129 and remove stale actionlint ignore

Group consecutive GITHUB_STEP_SUMMARY redirects into a single block
to satisfy SC2129. Drop the "could not parse as YAML" ignore for
ai-labeler.yml since the inline Python that caused it is gone.

Author: jeremy

.github/actionlint.yaml

@@ -4,12 +4,6 @@ self-hosted-runner:
 config-variables: null
 
 paths:
-  # ai-labeler.yml embeds Python in a YAML run block that actionlint
-  # can't parse as valid workflow YAML.
-  .github/workflows/ai-labeler.yml:
-    ignore:
-      - 'could not parse as YAML'
-
   # SC2086 fires on ${{ }} expressions which are interpolated by GitHub
   # Actions before the shell sees them. Safe to ignore repo-wide.
   .github/workflows/**/*.yml:

.github/scripts/splice-prompt.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+"""Splice /tmp/user-message.txt into a prompt YAML's messages array."""
+import sys, yaml
+
+prompt_file = sys.argv[1]
+output_file = sys.argv[2]
+
+with open(prompt_file) as f:
+    lines = f.readlines()
+with open('/tmp/user-message.txt') as f:
+    user_msg = f.read()
+
+# Find where messages array ends: first non-blank top-level key after 'messages:'
+insert_at = len(lines)
+for i, line in enumerate(lines):
+    if i == 0:
+        continue
+    if line.strip() and not line[0].isspace():
+        insert_at = i
+        break
+
+entry = ['  - role: user\n', '    content: |\n']
+for ln in user_msg.splitlines():
+    entry.append('      ' + ln + '\n')
+
+lines[insert_at:insert_at] = entry
+with open(output_file, 'w') as f:
+    f.writelines(lines)
+
+# Validate: last message must be the user message we just added
+doc = yaml.safe_load(open(output_file))
+assert doc['messages'][-1]['role'] == 'user', 'prompt splice failed: last message is not user'

.github/workflows/ai-labeler.yml

@@ -41,34 +41,7 @@ jobs:
 
           # Build full prompt YAML: splice user message into the messages array
           # (avoids yaml round-trip which reorders keys and changes scalar styles)
-          python3 -c "
-with open('.github/prompts/classify-pr.prompt.yml') as f:
-    lines = f.readlines()
-with open('/tmp/user-message.txt') as f:
-    user_msg = f.read()
-
-# Find where messages array ends: first non-blank top-level key after 'messages:'
-insert_at = len(lines)
-for i, line in enumerate(lines):
-    if i == 0:
-        continue
-    if line.strip() and not line[0].isspace():
-        insert_at = i
-        break
-
-entry = ['  - role: user\n', '    content: |\n']
-for ln in user_msg.splitlines():
-    entry.append('      ' + ln + '\n')
-
-lines[insert_at:insert_at] = entry
-with open('/tmp/prompt.yml', 'w') as f:
-    f.writelines(lines)
-
-# Validate: last message must be the user message we just added
-import yaml
-doc = yaml.safe_load(open('/tmp/prompt.yml'))
-assert doc['messages'][-1]['role'] == 'user', 'prompt splice failed: last message is not user'
-          "
+          python3 .github/scripts/splice-prompt.py .github/prompts/classify-pr.prompt.yml /tmp/prompt.yml
 
       - name: Classify
         id: classify
@@ -151,34 +124,7 @@ assert doc['messages'][-1]['role'] == 'user', 'prompt splice failed: last messag
 
             # Build full prompt YAML: splice user message into the messages array
             # (avoids yaml round-trip which reorders keys and changes scalar styles)
-            python3 -c "
-with open('.github/prompts/detect-breaking.prompt.yml') as f:
-    lines = f.readlines()
-with open('/tmp/user-message.txt') as f:
-    user_msg = f.read()
-
-# Find where messages array ends: first non-blank top-level key after 'messages:'
-insert_at = len(lines)
-for i, line in enumerate(lines):
-    if i == 0:
-        continue
-    if line.strip() and not line[0].isspace():
-        insert_at = i
-        break
-
-entry = ['  - role: user\n', '    content: |\n']
-for ln in user_msg.splitlines():
-    entry.append('      ' + ln + '\n')
-
-lines[insert_at:insert_at] = entry
-with open('/tmp/prompt.yml', 'w') as f:
-    f.writelines(lines)
-
-# Validate: last message must be the user message we just added
-import yaml
-doc = yaml.safe_load(open('/tmp/prompt.yml'))
-assert doc['messages'][-1]['role'] == 'user', 'prompt splice failed: last message is not user'
-            "
+            python3 .github/scripts/splice-prompt.py .github/prompts/detect-breaking.prompt.yml /tmp/prompt.yml
             echo "skip=false" >> $GITHUB_OUTPUT
           fi
 
@@ -198,11 +144,13 @@ assert doc['messages'][-1]['role'] == 'user', 'prompt splice failed: last messag
           RESPONSE_FILE="${{ steps.detect.outputs.response-file }}"
           if ! jq empty "$RESPONSE_FILE" 2>/dev/null; then
             echo "::warning::Model response is not valid JSON; skipping breaking label. See step summary for details."
-            echo "## Breaking change detection failed" >> "$GITHUB_STEP_SUMMARY"
-            echo "Model returned invalid JSON. Breaking label was **not** applied." >> "$GITHUB_STEP_SUMMARY"
-            echo '```' >> "$GITHUB_STEP_SUMMARY"
-            cat "$RESPONSE_FILE" >> "$GITHUB_STEP_SUMMARY"
-            echo '```' >> "$GITHUB_STEP_SUMMARY"
+            {
+              echo "## Breaking change detection failed"
+              echo "Model returned invalid JSON. Breaking label was **not** applied."
+              echo '```'
+              cat "$RESPONSE_FILE"
+              echo '```'
+            } >> "$GITHUB_STEP_SUMMARY"
             exit 0
           fi
           BREAKING=$(jq -r '.breaking' "$RESPONSE_FILE")
@@ -261,34 +209,7 @@ assert doc['messages'][-1]['role'] == 'user', 'prompt splice failed: last messag
 
             # Build full prompt YAML: splice user message into the messages array
             # (avoids yaml round-trip which reorders keys and changes scalar styles)
-            python3 -c "
-with open('.github/prompts/spec-impact.prompt.yml') as f:
-    lines = f.readlines()
-with open('/tmp/user-message.txt') as f:
-    user_msg = f.read()
-
-# Find where messages array ends: first non-blank top-level key after 'messages:'
-insert_at = len(lines)
-for i, line in enumerate(lines):
-    if i == 0:
-        continue
-    if line.strip() and not line[0].isspace():
-        insert_at = i
-        break
-
-entry = ['  - role: user\n', '    content: |\n']
-for ln in user_msg.splitlines():
-    entry.append('      ' + ln + '\n')
-
-lines[insert_at:insert_at] = entry
-with open('/tmp/prompt.yml', 'w') as f:
-    f.writelines(lines)
-
-# Validate: last message must be the user message we just added
-import yaml
-doc = yaml.safe_load(open('/tmp/prompt.yml'))
-assert doc['messages'][-1]['role'] == 'user', 'prompt splice failed: last message is not user'
-            "
+            python3 .github/scripts/splice-prompt.py .github/prompts/spec-impact.prompt.yml /tmp/prompt.yml
             echo "skip=false" >> $GITHUB_OUTPUT
           fi