[Pages] Flag server logic with-pattern issues (#129)

* Flag server logic with-pattern issues

- Detect raw with( substrings before server-side validation fails at runtime
- Document OData startswith/endswith literal splitting workaround
- Add tests for rejected and accepted startswith patterns

Co-authored-by: GPT-5.5 <223556219+Copilot@users.noreply.github.com>
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Update troubleshooting section in SKILL.md

- 📝 Clarified the diagnostic log retrieval process.
- 🔄 Removed specific references to the Power Pages design studio diagnostics view.
- 🔍 Updated instructions for using Playwright MCP tools.
- ❌ Removed unnecessary steps and streamlined the troubleshooting flow.

-Priyanshu

---------

Co-authored-by: Priyanshu Agrawal <priyanshuag@Priyanshus-MacBook-Pro.local>
Co-authored-by: GPT-5.5 <223556219+Copilot@users.noreply.github.com>

Author: 3 people

plugins/power-pages/scripts/tests/validate-serverlogic.test.js

@@ -228,3 +228,42 @@ test('yml name mismatch is flagged', (t) => {
   assert.equal(result.status, 2);
   assert.match(result.stderr, /does not match folder name/);
 });
+
+test('startswith( inside string literal is flagged (with-pattern)', (t) => {
+  const projectRoot = createTempProject(t);
+  setupProject(projectRoot);
+  const startsWithJs = `function get() {
+    try {
+        Server.Logger.Log("test-endpoint GET called");
+        var query = "$filter=startswith(name,'INV-')";
+        return JSON.stringify({ status: "success", query: query });
+    } catch (err) {
+        Server.Logger.Error("test-endpoint GET failed: " + err.message);
+        return JSON.stringify({ status: "error", message: err.message });
+    }
+}`;
+  writeServerLogic(projectRoot, 'test-endpoint', startsWithJs, VALID_YML);
+
+  const result = runValidator(projectRoot);
+  assert.equal(result.status, 2);
+  assert.match(result.stderr, /contains the substring 'with\('/);
+});
+
+test('split startswith( workaround passes validation', (t) => {
+  const projectRoot = createTempProject(t);
+  setupProject(projectRoot);
+  const splitJs = `function get() {
+    try {
+        Server.Logger.Log("test-endpoint GET called");
+        var query = "$filter=startswith" + "(name,'INV-')";
+        return JSON.stringify({ status: "success", query: query });
+    } catch (err) {
+        Server.Logger.Error("test-endpoint GET failed: " + err.message);
+        return JSON.stringify({ status: "error", message: err.message });
+    }
+}`;
+  writeServerLogic(projectRoot, 'test-endpoint', splitJs, VALID_YML);
+
+  const result = runValidator(projectRoot);
+  assert.equal(result.status, 0, result.stderr);
+});

plugins/power-pages/skills/add-server-logic/SKILL.md

@@ -432,6 +432,26 @@ Repeat this step for each approved server logic item. Create or update `<PROJECT
 6. **No browser APIs**: No `fetch`, `XMLHttpRequest`, `setTimeout`, `setInterval`, `console.log`, or DOM APIs.
 7. **Async when needed**: Mark functions as `async` only when they use `await` (HttpClient calls). Dataverse connector methods (`Server.Connector.Dataverse.*`) are **synchronous** — do NOT use `async`/`await` with them.
 
+#### Prohibited Script Patterns
+
+The Power Pages server-side script validator rejects scripts containing certain patterns at runtime. Violations surface as `RTSL01: Script validation failed: prohibited pattern found - Pattern: <regex>` in diagnostics, and the function silently falls through without executing user code.
+
+| Pattern | Regex | Caveat |
+|---------|-------|--------|
+| JavaScript `with` statement | `with\s*\(` | The regex matches the substring `with(` **anywhere** in the file — including inside string literals and inside other identifiers. OData filter functions like `startswith(`, `endswith(`, and `groupwith(` will trip it because they end with `with(`. |
+
+**Workaround for OData functions** — split the literal so `with(` is not contiguous in source:
+
+```javascript
+// ❌ Triggers validator: "startswith(" contains the substring "with("
+var query = "$filter=startswith(name,'INV-')";
+
+// ✅ Split the literal — server still receives "startswith(name,...)"
+var query = "$filter=startswith" + "(name,'INV-')";
+```
+
+The same trick applies to `endswith(`, `groupwith(`, and any other identifier that ends with `with(`.
+
 #### Code Template
 
 ```javascript
@@ -1112,6 +1132,7 @@ Provide testing instructions:
 Use the frontend integration reference from Phase 9 for the exact calling pattern that matches the site's stack.
 
 5. **Check diagnostics** — Server.Logger output can be viewed in Power Pages design studio diagnostics
+6. **If the endpoint returns an error or unexpected response** — see [Troubleshooting Server Logic Execution Errors](#troubleshooting-server-logic-execution-errors) for the Playwright + `X-Ms-UserTrace` debugging flow
 
 **Output**: Code validated, API URL provided, test guidance given
 
@@ -1188,6 +1209,46 @@ After deployment (or if skipped), remind the user:
 
 ---
 
+## Troubleshooting Server Logic Execution Errors
+
+When a deployed server logic endpoint returns an error or unexpected response, the underlying cause is usually hidden inside the `X-Ms-UserTrace` response header — a base64-encoded blob containing the runtime diagnostic logs. The Power Pages Edge browser extension shows the same data, but inspecting the response header is the fastest path when iterating against a live site.
+
+Use this flow whenever a server logic call fails or returns a different response than expected:
+
+### 1. Open the Live Site in a Browser via Playwright
+
+Use the Playwright MCP tools to drive the site:
+
+1. Navigate to the deployed site URL (the `websiteUrl` returned by `/activate-site` or shown in the Power Pages admin center).
+2. Ask the user to sign in if the endpoint requires authentication and wait for confirmation.
+3. Trigger the action that calls the failing server logic endpoint (click the button, submit the form, etc.) — or call the endpoint directly with `fetch()`.
+
+### 2. Capture the Network Response
+
+Use `mcp__plugin_power-pages_playwright__browser_network_requests` to list network activity, then locate the request to `/_api/serverlogics/<name>`. Note:
+
+- The HTTP status code (e.g., 200, 400, 500)
+- The response body (often a generic error or empty payload when validation fails)
+- **Most importantly: the `X-Ms-UserTrace` response header** — this is where the actual diagnostic logs live
+
+If `browser_network_requests` does not surface the response headers directly, fall back to `mcp__plugin_power-pages_playwright__browser_evaluate` and read the headers from a `fetch()` call:
+
+```javascript
+const res = await fetch('/_api/serverlogics/<name>', { method: 'GET', credentials: 'include' });
+const trace = res.headers.get('X-Ms-UserTrace');
+return { status: res.status, body: await res.text(), trace };
+```
+
+### 3. Decode the `X-Ms-UserTrace` Header
+
+The header value is base64-encoded JSON. Decode it.
+
+The decoded payload contains the diagnostic log entries — including the actual error message, the prohibited pattern (if script validation failed).
+
+After fixing, redeploy via `/deploy-site` and restart the site so the change is picked up immediately.
+
+---
+
 ## Important Notes
 
 ### Throughout All Phases

plugins/power-pages/skills/add-server-logic/scripts/validate-serverlogic.js

@@ -202,6 +202,24 @@ runValidation((cwd) => {
     if (/(?:async\s+)?function\s+delete\s*\(/m.test(strippedContent)) {
       errors.push(`${dirName}.js: uses 'function delete()' — 'delete' is a reserved word, use 'del' instead`);
     }
+
+    // Check: no 'with(' substring anywhere in the raw source.
+    // The Power Pages server validator rejects scripts matching /with\s*\(/ to block
+    // the JavaScript `with` statement, but the regex also matches the substring inside
+    // identifiers like `startswith(`, `endswith(`, and `groupwith(` — even inside string
+    // literals — which causes runtime error: "Script validation failed: prohibited
+    // pattern found - Pattern: with\s*\(". Run this on the raw content (not stripped)
+    // because the server validator does the same.
+    const withMatches = [...content.matchAll(/with\s*\(/g)];
+    if (withMatches.length > 0) {
+      const lineNumbers = withMatches.map(m => content.slice(0, m.index).split('\n').length);
+      errors.push(
+        `${dirName}.js: contains the substring 'with(' on line(s) ${lineNumbers.join(', ')} — ` +
+        `the Power Pages server validator's regex /with\\s*\\(/ blocks this even inside string literals ` +
+        `(e.g., OData functions like startswith(, endswith(). Split the literal so 'with(' is not contiguous, ` +
+        `e.g., \`"startswith" + "(crd50_name,..."\` instead of \`"startswith(crd50_name,..."\`.`
+      );
+    }
   }
 
   if (errors.length > 0) {