Fix dead UTF-8 validation check and PR failure losing commit info

Bug 1: Replace no-op Buffer.from try/catch with real unpaired surrogate
detection. Buffer.from(string, utf-8) never throws for JS strings, making
the previous check dead code. The new regex detects lone surrogates which
are valid in JS strings but not valid UTF-8.

Bug 2: Wrap PR creation in its own try/catch so a PR failure (network,
permissions, rate limit) does not lose the successful commit metadata.
Previously commitResult was scoped inside try and inaccessible from catch,
causing the error response to report Write failed with no commit info.

Author: cursoragent

src/core/actions.js

@@ -623,18 +623,24 @@ export async function handleAction(params) {
 
           // --- Handle PR if requested (Tier 3) ---
           let prResult = null;
+          let prError = null;
           // TODO: Orphan prevention (Layer 4) — before creating a new PR, check for
           // existing open PRs from oddkit on the same branch or targeting the same files.
           // If found, push to the existing branch instead (the PR updates automatically).
           // The output interface supports this via pr_updated. Deferred until Layer 4.
           if (pr && branch) {
-            const prOpts = typeof pr === "object" ? pr : {};
-            const prTitle = prOpts.title || message;
-            const prBody = prOpts.body || `Files:\n${files.map((f) => `- ${f.path}`).join("\n")}\n\n---\nWritten via oddkit_write`;
-            const prDraft = prOpts.draft || false;
-            const baseBranch = defaultBranch || await getDefaultBranch(owner, repoName);
-            prResult = await createPR(owner, repoName, prTitle, prBody, branch, baseBranch, prDraft);
-            status = "pr_opened";
+            try {
+              const prOpts = typeof pr === "object" ? pr : {};
+              const prTitle = prOpts.title || message;
+              const prBody = prOpts.body || `Files:\n${files.map((f) => `- ${f.path}`).join("\n")}\n\n---\nWritten via oddkit_write`;
+              const prDraft = prOpts.draft || false;
+              const baseBranch = defaultBranch || await getDefaultBranch(owner, repoName);
+              prResult = await createPR(owner, repoName, prTitle, prBody, branch, baseBranch, prDraft);
+              status = "pr_opened";
+            } catch (prErr) {
+              prError = prErr.message;
+              status = "committed_pr_failed";
+            }
           }
 
           const filesWritten = files.map((f) => f.path);
@@ -652,10 +658,11 @@ export async function handleAction(params) {
               files_written: filesWritten,
               pr_url: prResult?.pr_url || undefined,
               pr_number: prResult?.pr_number || undefined,
+              pr_error: prError || undefined,
               pr_updated: false, // TODO: set to true when orphan prevention detects existing PR
               validation,
             },
-            assistant_text: `Successfully wrote ${filesWritten.length} file(s) to ${owner}/${repoName} on branch ${targetBranch}. Commit: ${commitResult.commit_url}${prResult ? `\nPR: ${prResult.pr_url}` : ""}${validationWarnings ? `\n\nValidation warnings: ${validationWarnings}` : ""}`,
+            assistant_text: `Successfully wrote ${filesWritten.length} file(s) to ${owner}/${repoName} on branch ${targetBranch}. Commit: ${commitResult.commit_url}${prResult ? `\nPR: ${prResult.pr_url}` : ""}${prError ? `\nPR creation failed: ${prError}` : ""}${validationWarnings ? `\n\nValidation warnings: ${validationWarnings}` : ""}`,
             debug: makeDebug({ files_count: files.length, tier: files.length === 1 ? 1 : 2, validation_passed: validation.passed }),
           };
 

src/utils/writeValidation.js

@@ -51,17 +51,14 @@ export function validateFile(path, content) {
         : null,
   });
 
-  // UTF-8 validity
-  try {
-    Buffer.from(content, "utf-8");
-    checks.push({ name: "utf8_valid", passed: true });
-  } catch {
-    checks.push({
-      name: "utf8_valid",
-      passed: false,
-      message: "Content is not valid UTF-8",
-    });
-  }
+  // UTF-8 validity — detect unpaired surrogates (valid in JS strings but not in UTF-8)
+  const hasLoneSurrogates =
+    /[\uD800-\uDBFF](?![\uDC00-\uDFFF])|(?<![\uD800-\uDBFF])[\uDC00-\uDFFF]/.test(content);
+  checks.push({
+    name: "utf8_valid",
+    passed: !hasLoneSurrogates,
+    message: hasLoneSurrogates ? "Content contains unpaired surrogate characters (not valid UTF-8)" : null,
+  });
 
   // Governed file checks (canon/, odd/, docs/)
   const isGoverned = path.startsWith("canon/") || path.startsWith("odd/") || path.startsWith("docs/");