Deduplicator fixes (#4635)

.github/prompts/issue-deduplicator.txt

@@ -5,7 +5,7 @@ You will receive the following JSON files located in the current working directo
 - `codex-existing-issues.json`: JSON array of recent issues (each element includes number, title, body, createdAt).
 
 Instructions:
-- Load both files as JSON and review their contents carefully.
+- Load both files as JSON and review their contents carefully. The codex-existing-issues.json file is large, ensure you explore all of it.
 - Compare the current issue against the existing issues to find up to five that appear to describe the same underlying problem or request.
 - Only consider an issue a potential duplicate if there is a clear overlap in symptoms, feature requests, reproduction steps, or error messages.
 - Prioritize newer issues when similarity is comparable.
@@ -16,4 +16,3 @@ Output requirements:
 - Respond with a JSON array of issue numbers (integers), ordered from most likely duplicate to least.
 - Include at most five numbers.
 - If you find no plausible duplicates, respond with `[]`.
-- Do not emit any additional commentary, text, or keys beyond the JSON array.

.github/workflows/issue-deduplicator.yml

@@ -73,6 +73,11 @@ jobs:
               return;
             }
 
+            if (numbers.length === 0) {
+              core.info('Codex reported no potential duplicates.');
+              return;
+            }
+
             const lines = ['Potential duplicates detected:', ...numbers.map((value) => `- #${value}`)];
 
             await github.rest.issues.createComment({
@@ -86,6 +91,7 @@ jobs:
         if: ${{ always() && github.event.action == 'labeled' && github.event.label.name == 'codex-deduplicate' }}
         env:
           GH_TOKEN: ${{ github.token }}
+          GH_REPO: ${{ github.repository }}
         run: |
           gh issue edit "${{ github.event.issue.number }}" --remove-label codex-deduplicate || true
           echo "Attempted to remove label: codex-deduplicate"