diff --git a/sdk/go/protomcp/workflow.go b/sdk/go/protomcp/workflow.go
index 5314dd6..f8c680a 100644
--- a/sdk/go/protomcp/workflow.go
+++ b/sdk/go/protomcp/workflow.go
@@ -366,10 +366,18 @@ func HandleStepCall(workflowName, stepName string, ctx ToolContext, args map[str
 	state := getActiveState()
 
 	if stepDef.Initial {
-		// Start a new workflow
+		// Start a new workflow — snapshot pre-workflow tools
 		var preTools []string
 		if ToolManagerAdapter.GetActiveTools != nil {
 			preTools = ToolManagerAdapter.GetActiveTools()
+		} else {
+			// Compute from registered tools, excluding this workflow's own tools
+			prefix := workflowName + "."
+			for _, t := range GetRegisteredTools() {
+				if !strings.HasPrefix(t.Name, prefix) {
+					preTools = append(preTools, t.Name)
+				}
+			}
 		}
 		newState := WorkflowState{
 			WorkflowName:     workflowName,
@@ -485,7 +493,16 @@ func HandleStepCall(workflowName, stepName string, ctx ToolContext, args map[str
 		}
 		r := Result(resultText)
 		r.EnableTools = state.PreWorkflowTools
-		r.DisableTools = []string{}
+		// Disable everything not in pre-workflow set
+		preSet := map[string]bool{}
+		for _, t := range state.PreWorkflowTools {
+			preSet[t] = true
+		}
+		for _, t := range GetRegisteredTools() {
+			if !preSet[t.Name] {
+				r.DisableTools = append(r.DisableTools, t.Name)
+			}
+		}
 		return r
 	}
 
@@ -531,14 +548,22 @@ func HandleCancel(workflowName string) ToolResult {
 		wf.OnCancelFn(state.CurrentStep, state.History)
 	}
 
-	// Restore pre-workflow tools
+	// Restore pre-workflow tools — disable everything not in pre-workflow set
 	if ToolManagerAdapter.SetAllowed != nil {
 		ToolManagerAdapter.SetAllowed(state.PreWorkflowTools)
 	}
 	activeWorkflowStack = activeWorkflowStack[:len(activeWorkflowStack)-1]
 	r := Result(fmt.Sprintf("Workflow '%s' cancelled", workflowName))
 	r.EnableTools = state.PreWorkflowTools
-	r.DisableTools = []string{}
+	preSet := map[string]bool{}
+	for _, t := range state.PreWorkflowTools {
+		preSet[t] = true
+	}
+	for _, t := range GetRegisteredTools() {
+		if !preSet[t.Name] {
+			r.DisableTools = append(r.DisableTools, t.Name)
+		}
+	}
 	return r
 }
 
diff --git a/sdk/rust/src/workflow.rs b/sdk/rust/src/workflow.rs
index b19e771..2f8bee7 100644
--- a/sdk/rust/src/workflow.rs
+++ b/sdk/rust/src/workflow.rs
@@ -386,19 +386,12 @@ fn compute_transition(
     }
 
     // enable_tools = allowed_tools
-    // disable_tools = all workflow tools NOT in allowed (to hide them)
-    let all_wf_tools: Vec<String> = wf.steps.iter().map(|s| format!("{}.{}", wf.name, s.name)).collect();
-    let cancel_tool = format!("{}.cancel", wf.name);
-
-    let mut disable_tools: Vec<String> = Vec::new();
-    for t in &all_wf_tools {
-        if !allowed_tools.contains(t) {
-            disable_tools.push(t.clone());
-        }
-    }
-    if !allowed_tools.contains(&cancel_tool) {
-        disable_tools.push(cancel_tool);
-    }
+    // disable_tools = all registered tools NOT in allowed set
+    let allowed_set: std::collections::HashSet<&String> = allowed_tools.iter().collect();
+    let disable_tools: Vec<String> = all_tool_names.iter()
+        .filter(|t| !allowed_set.contains(t))
+        .cloned()
+        .collect();
 
     (allowed_tools, disable_tools)
 }
@@ -454,11 +447,19 @@ fn handle_step_call(workflow_name: &str, step_name: &str, ctx: ToolContext, args
         }
     }
 
+    // Drop state lock before calling handler to avoid deadlock if handler
+    // accesses workflow state. Registry lock (guard) is still held since
+    // handler lives in the registry, but that's unavoidable without Arc.
+    drop(state_guard);
+
     // Run handler, catch panics as errors
     let handler_result = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
         (step_def.handler)(ctx, args)
     }));
 
+    // Re-acquire state lock after handler call
+    let mut state_guard = ACTIVE_WORKFLOW.lock().unwrap_or_else(|e| e.into_inner());
+
     match handler_result {
         Err(panic_info) => {
             // Handler panicked — treat as error
diff --git a/sdk/typescript/src/workflow.ts b/sdk/typescript/src/workflow.ts
index d9d2055..5957b23 100644
--- a/sdk/typescript/src/workflow.ts
+++ b/sdk/typescript/src/workflow.ts
@@ -344,12 +344,15 @@ async function handleStepCall(workflowName: string, stepName: string, kwargs: Re
     if (wf.onComplete) {
       wf.onComplete(state!.history);
     }
-    // Restore pre-workflow tools
+    // Restore pre-workflow tools — disable everything not in pre-workflow set
+    const allToolNames = getRegisteredTools().map(t => t.name);
+    const preSet = new Set(state!.preWorkflowTools);
+    const terminalDisableTools = allToolNames.filter(t => !preSet.has(t));
     activeWorkflowStack.pop();
     return new ToolResult({
       result: result.result || 'Workflow complete',
       enableTools: state!.preWorkflowTools,
-      disableTools: [],
+      disableTools: terminalDisableTools,
     });
   } else {
     // Transition to next steps
@@ -387,12 +390,15 @@ function handleCancel(workflowName: string): ToolResult {
     wf.onCancel(state.currentStep, state.history);
   }
 
-  // Restore pre-workflow tools
+  // Restore pre-workflow tools — disable everything not in pre-workflow set
+  const allToolNames = getRegisteredTools().map(t => t.name);
+  const preSet = new Set(state.preWorkflowTools);
+  const cancelDisableTools = allToolNames.filter(t => !preSet.has(t));
   activeWorkflowStack.pop();
   return new ToolResult({
     result: `Workflow '${workflowName}' cancelled`,
     enableTools: state.preWorkflowTools,
-    disableTools: [],
+    disableTools: cancelDisableTools,
   });
 }