diff --git a/.archon/workflows/defaults/archon-adversarial-dev.yaml b/.archon/workflows/defaults/archon-adversarial-dev.yaml
index eecf4b72..2ab207dc 100644
--- a/.archon/workflows/defaults/archon-adversarial-dev.yaml
+++ b/.archon/workflows/defaults/archon-adversarial-dev.yaml
@@ -115,6 +115,7 @@ nodes:
   - id: adversarial-sprint
     depends_on: [init-workspace]
     idle_timeout: 600000
+    model: claude-opus-4-6[1m]
     loop:
       prompt: |
         # Adversarial Development — Sprint Loop
diff --git a/.archon/workflows/defaults/archon-feature-development.yaml b/.archon/workflows/defaults/archon-feature-development.yaml
index f63d9b1a..6d074770 100644
--- a/.archon/workflows/defaults/archon-feature-development.yaml
+++ b/.archon/workflows/defaults/archon-feature-development.yaml
@@ -8,6 +8,7 @@ description: |
 nodes:
   - id: implement
     command: archon-implement
+    model: claude-opus-4-6[1m]
 
   - id: create-pr
     command: archon-create-pr
diff --git a/.archon/workflows/defaults/archon-fix-github-issue.yaml b/.archon/workflows/defaults/archon-fix-github-issue.yaml
index 72713178..12ad675d 100644
--- a/.archon/workflows/defaults/archon-fix-github-issue.yaml
+++ b/.archon/workflows/defaults/archon-fix-github-issue.yaml
@@ -133,7 +133,7 @@ nodes:
     command: archon-fix-issue
     depends_on: [bridge-artifacts]
     context: fresh
-    model: opus
+    model: claude-opus-4-6[1m]
 
   # ═══════════════════════════════════════════════════════════════
   # PHASE 5: VALIDATE
diff --git a/.archon/workflows/defaults/archon-idea-to-pr.yaml b/.archon/workflows/defaults/archon-idea-to-pr.yaml
index 519429be..9329c550 100644
--- a/.archon/workflows/defaults/archon-idea-to-pr.yaml
+++ b/.archon/workflows/defaults/archon-idea-to-pr.yaml
@@ -52,6 +52,7 @@ nodes:
     command: archon-implement-tasks
     depends_on: [confirm-plan]
     context: fresh
+    model: claude-opus-4-6[1m]
 
   # ═══════════════════════════════════════════════════════════════════
   # PHASE 4: VALIDATE
diff --git a/.archon/workflows/defaults/archon-piv-loop.yaml b/.archon/workflows/defaults/archon-piv-loop.yaml
index b9b652e6..7227900c 100644
--- a/.archon/workflows/defaults/archon-piv-loop.yaml
+++ b/.archon/workflows/defaults/archon-piv-loop.yaml
@@ -415,6 +415,7 @@ nodes:
   - id: implement
     depends_on: [implement-setup]
     idle_timeout: 600000
+    model: claude-opus-4-6[1m]
     loop:
       prompt: |
         # PIV Loop — Implementation Agent
diff --git a/.archon/workflows/defaults/archon-plan-to-pr.yaml b/.archon/workflows/defaults/archon-plan-to-pr.yaml
index ef40e329..067c1a81 100644
--- a/.archon/workflows/defaults/archon-plan-to-pr.yaml
+++ b/.archon/workflows/defaults/archon-plan-to-pr.yaml
@@ -42,6 +42,7 @@ nodes:
     command: archon-implement-tasks
     depends_on: [confirm-plan]
     context: fresh
+    model: claude-opus-4-6[1m]
 
   # ═══════════════════════════════════════════════════════════════════
   # PHASE 4: VALIDATE
diff --git a/.archon/workflows/defaults/archon-ralph-dag.yaml b/.archon/workflows/defaults/archon-ralph-dag.yaml
index d258b2bb..5c0d7c90 100644
--- a/.archon/workflows/defaults/archon-ralph-dag.yaml
+++ b/.archon/workflows/defaults/archon-ralph-dag.yaml
@@ -189,6 +189,7 @@ nodes:
   - id: implement
     depends_on: [validate-prd]
     idle_timeout: 600000
+    model: claude-opus-4-6[1m]
     loop:
       prompt: |
         # Ralph Agent — Autonomous Story Implementation
diff --git a/.archon/workflows/defaults/archon-refactor-safely.yaml b/.archon/workflows/defaults/archon-refactor-safely.yaml
index 6ba72de7..56bc96ac 100644
--- a/.archon/workflows/defaults/archon-refactor-safely.yaml
+++ b/.archon/workflows/defaults/archon-refactor-safely.yaml
@@ -207,6 +207,7 @@ nodes:
   # ═══════════════════════════════════════════════════════════════
 
   - id: execute-refactor
+    model: claude-opus-4-6[1m]
     prompt: |
       You are executing a refactoring plan with strict safety guardrails.
 
diff --git a/packages/workflows/src/dag-executor.ts b/packages/workflows/src/dag-executor.ts
index 4660e612..f52ea5fe 100644
--- a/packages/workflows/src/dag-executor.ts
+++ b/packages/workflows/src/dag-executor.ts
@@ -1438,8 +1438,8 @@ async function executeBashNode(
 }
 
 /**
- * Build WorkflowAssistantOptions from workflow-level config.
- * Loop nodes use workflow-level provider/model only; per-node overrides are not supported.
+ * Build WorkflowAssistantOptions from resolved provider, model, and config.
+ * Caller is responsible for resolving per-node overrides before passing model.
  */
 function buildLoopNodeOptions(
   provider: 'claude' | 'codex',
@@ -2373,6 +2373,34 @@ export async function executeDagWorkflow(
 
           // 3b. Loop node dispatch — manages its own AI sessions and iteration
           if (isLoopNode(node)) {
+            // Resolve per-node provider/model overrides (same logic as other node types)
+            let loopProvider: 'claude' | 'codex';
+            if (node.provider) {
+              loopProvider = node.provider;
+            } else if (node.model && isClaudeModel(node.model)) {
+              loopProvider = 'claude';
+            } else if (node.model) {
+              loopProvider = 'codex';
+            } else {
+              loopProvider = workflowProvider;
+            }
+            const loopModel =
+              node.model ??
+              (loopProvider === workflowProvider
+                ? workflowModel
+                : config.assistants[loopProvider]?.model);
+
+            if (!isModelCompatible(loopProvider, loopModel)) {
+              return {
+                nodeId: node.id,
+                output: {
+                  state: 'failed' as const,
+                  output: '',
+                  error: `Node '${node.id}': model "${loopModel ?? 'default'}" is not compatible with provider "${loopProvider}"`,
+                },
+              };
+            }
+
             const output = await executeLoopNode(
               deps,
               platform,
@@ -2380,8 +2408,8 @@ export async function executeDagWorkflow(
               cwd,
               workflowRun,
               node,
-              workflowProvider,
-              workflowModel,
+              loopProvider,
+              loopModel,
               artifactsDir,
               logDir,
               baseBranch,