ci: use Muse Spark 1.3 for PR walkthrough (#3674)

.github/scripts/pr-walkthrough-workflow-contract_test.py

@@ -183,7 +183,7 @@ class PRWalkthroughWorkflowContractTest(unittest.TestCase):
         self.assertIn("arbitrary Git or shell commands", self.skill)
 
     def test_generation_uses_requested_model_native_high_reasoning_variant(self) -> None:
-        model = "opencode-go/muse-spark-1.2-contributor"
+        model = "opencode-go/muse-spark-1.3-contributor"
         variant = "high"
         self.assertIn(f"PR_WALKTHROUGH_MODEL: {model}", self.workflow)
         self.assertIn(f"PR_WALKTHROUGH_VARIANT: {variant}", self.workflow)

.github/workflows/pr-walkthrough.yml

@@ -8,7 +8,7 @@ on:
     types: [opened, ready_for_review, reopened, synchronize, labeled]
 
 env:
-  PR_WALKTHROUGH_MODEL: opencode-go/muse-spark-1.2-contributor
+  PR_WALKTHROUGH_MODEL: opencode-go/muse-spark-1.3-contributor
   PR_WALKTHROUGH_VARIANT: high
 
 concurrency:
@@ -152,7 +152,7 @@ jobs:
           ---
           description: Generate and render a visual pull request walkthrough.
           mode: primary
-          model: "opencode-go/muse-spark-1.2-contributor"
+          model: "opencode-go/muse-spark-1.3-contributor"
           temperature: 0.1
           permission:
             "*": deny

docs/specs/ui/requirements/pr-walkthrough.md

@@ -92,7 +92,7 @@ the dedicated Cloudflare R2 walkthrough bucket. Lifecycle controls retention.
   variable. The trusted, non-generating repair path for edited descriptions is
   in `.github/workflows/pr-walkthrough-reconcile.yml`. It does not share the
   `OPENCODE_REVIEW_ENABLED` code-review gate.
-- The initial runner uses `opencode-go/muse-spark-1.2-contributor` and its
+- The initial runner uses `opencode-go/muse-spark-1.3-contributor` and its
   built-in `high` reasoning variant. The workflow passes these values with the
   OpenCode 1.17.7 `--model` and `--variant` options.
 - The workflow preserves the generated JSON and HTML as CI artifacts and