feat: add canonical workflow prompt library to web UI (Closes #428)

Expose short copy/paste operator prompts on /prompts derived from canonical
workflow files with workflow path and SHA-256 hash. Adds JSON export at
/api/prompts, copy buttons, and tests.

Co-Authored-By: Claude Opus 4.8 (1M context) <[email protected]>

tests/test_webui_prompt_library.py

@@ -0,0 +1,81 @@
+"""Tests for web UI prompt library (#428)."""
+import sys
+import unittest
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from starlette.testclient import TestClient
+
+from webui.app import create_app
+from webui.prompt_library import load_prompt_library, prompt_to_dict
+
+
+class TestWebuiPromptLibrary(unittest.TestCase):
+    def setUp(self):
+        self.client = TestClient(create_app())
+
+    def test_library_has_required_prompts(self):
+        entries = load_prompt_library()
+        slugs = {entry.slug for entry in entries}
+        self.assertEqual(
+            slugs,
+            {
+                "review-pr",
+                "work-issue",
+                "create-issue",
+                "comment-issue",
+                "cleanup",
+                "audit",
+                "onboarding",
+            },
+        )
+
+    def test_workflow_entries_include_hash_and_task_mode(self):
+        review = next(e for e in load_prompt_library() if e.slug == "review-pr")
+        self.assertEqual(
+            review.workflow_path,
+            "skills/llm-project-workflow/workflows/review-merge-pr.md",
+        )
+        self.assertEqual(review.task_mode, "review-merge-pr")
+        self.assertIsNotNone(review.workflow_hash)
+        self.assertGreater(len(review.workflow_hash), 12)
+        self.assertIn("eligible open PR", review.prompt_text)
+
+    def test_comment_issue_defers_to_workflow(self):
+        comment = next(e for e in load_prompt_library() if e.slug == "comment-issue")
+        self.assertIn("comment_issue", comment.prompt_text)
+        self.assertIn("create-issue", comment.workflow_path)
+        self.assertIn("§16", comment.source_note)
+
+    def test_prompts_page_renders_cards_and_copy_buttons(self):
+        response = self.client.get("/prompts")
+        self.assertEqual(response.status_code, 200)
+        text = response.text
+        self.assertIn("Prompt library", text)
+        self.assertIn("review-merge-pr.md", text)
+        self.assertIn("Copy prompt", text)
+        self.assertIn('data-copy-target="prompt-review-pr"', text)
+        self.assertNotIn("child issue", text.lower())
+
+    def test_api_prompts_json(self):
+        response = self.client.get("/api/prompts")
+        self.assertEqual(response.status_code, 200)
+        data = response.json()
+        self.assertEqual(data["count"], 7)
+        self.assertEqual(len(data["prompts"]), 7)
+        first = data["prompts"][0]
+        self.assertIn("slug", first)
+        self.assertIn("prompt_text", first)
+        self.assertIn("workflow_path", first)
+        self.assertIn("workflow_hash", first)
+
+    def test_prompt_to_dict_round_trip(self):
+        entry = load_prompt_library()[0]
+        payload = prompt_to_dict(entry)
+        self.assertEqual(payload["slug"], entry.slug)
+        self.assertEqual(payload["prompt_text"], entry.prompt_text)
+
+
+if __name__ == "__main__":
+    unittest.main()

tests/test_webui_skeleton.py

@@ -30,12 +30,17 @@ class TestWebuiSkeleton(unittest.TestCase):
         self.assertIn("Read-only MVP", response.text)
 
     def test_route_stubs_render(self):
-        for path in ("/prompts", "/runtime", "/audit"):
+        for path in ("/runtime", "/audit"):
             with self.subTest(path=path):
                 response = self.client.get(path)
                 self.assertEqual(response.status_code, 200)
                 self.assertIn("child issue", response.text.lower())
 
+    def test_prompts_is_implemented(self):
+        response = self.client.get("/prompts")
+        self.assertEqual(response.status_code, 200)
+        self.assertIn("Prompt library", response.text)
+
     def test_projects_is_implemented(self):
         response = self.client.get("/projects")
         self.assertEqual(response.status_code, 200)