Enable inline sub-agents by default; deprecate features.inline-agents; reject inline-sub-agents: false

.github/aw/subagents.md

@@ -6,8 +6,6 @@ description: Guide for defining inline sub-agents in workflow markdown files —
 
 Inline sub-agents let you define specialised agents directly inside a workflow markdown file. At runtime the sub-agent sections are extracted from the prompt (after `{{#runtime-import}}` macros are resolved) and written to the engine-specific agents directory so the engine CLI can discover and invoke them.
 
-> **Experimental feature.** Compilation emits `⚠ Using experimental feature: inline-sub-agents` whenever a workflow contains at least one `## agent:` block.
-
 ---
 
 ## Enabling the Feature
@@ -21,6 +19,8 @@ engine: copilot
 ```
 
 > `features.inline-agents` is deprecated and no longer needed. Existing workflows may still include it, but it has no effect.
+>
+> `inline-sub-agents: false` is not supported and fails compilation. Remove the field.
 
 ---
 
@@ -200,4 +200,5 @@ changes. Return a bulleted list, one bullet per file.
 - Sub-agents do not support `engine:`, `tools:`, `network:`, or `mcp-servers:` fields — those are stripped at runtime.
 - Sub-agents cannot define their own safe-output jobs.
 - `features.inline-agents` is deprecated and has no effect; inline sub-agent upload/restore is always generated.
+- `inline-sub-agents: false` is rejected at compile time; inline sub-agents cannot be disabled.
 - Sub-agent blocks must appear in the main workflow file body; they are not resolved inside imported shared files.

docs/src/content/docs/patterns/data-ops.md

@@ -186,11 +186,9 @@ main agent:     → orchestrates sub-agents, synthesizes final report (high-reas
 
 ### Enabling inline sub-agents
 
-Add the `inline-agents` feature flag and the `cli-proxy` tool so sub-agents can make authenticated GitHub API calls:
+Inline sub-agents are enabled by default. Add `cli-proxy` so sub-agents can make authenticated GitHub API calls:
 
 ```yaml
-features:
-  inline-agents: true
 tools:
   cli-proxy: true
 ```

docs/src/content/docs/reference/inline-sub-agents.md

@@ -7,6 +7,8 @@ sidebar:
 
 An inline sub-agent is a named agent definition embedded directly in a workflow markdown file. Instead of creating a separate file in `.github/agents/`, you define the agent's frontmatter and instructions in a dedicated section of the same workflow file.
 
+Inline sub-agents are enabled by default. `features.inline-agents` is deprecated/no-op, and `inline-sub-agents: false` is rejected at compile time.
+
 ## Syntax
 
 Start a sub-agent block with a level-2 heading in the following form:

pkg/cli/codemod_inline_agents_test.go

@@ -12,6 +12,7 @@ import (
 
 func TestInlineAgentsFeatureRemovalCodemod(t *testing.T) {
 	codemod := getInlineAgentsFeatureRemovalCodemod()
+	assert.Equal(t, "1.0.0", codemod.IntroducedIn)
 
 	tests := []struct {
 		name        string

pkg/parser/schemas/main_workflow_schema.json

@@ -2720,6 +2720,11 @@
         }
       ]
     },
+    "inline-sub-agents": {
+      "type": "boolean",
+      "description": "Deprecated switch for inline sub-agent support. Inline sub-agents are enabled by default. Setting this to false is not supported and causes a compilation error.",
+      "examples": [true]
+    },
     "features": {
       "description": "Feature flags and configuration options for experimental or optional features in the workflow. Each feature can be a boolean flag or a string value. The 'action-tag' feature (string) specifies the tag or SHA to use when referencing actions/setup in compiled workflows (for testing purposes only).",
       "type": "object",

pkg/workflow/compiler_orchestrator_tools.go

@@ -61,11 +61,7 @@ func (c *Compiler) processToolsAndMarkdown(result *parser.FrontmatterResult, cle
 		return nil, fmt.Errorf("failed to extract inline sub-agents: %w", err)
 	}
 	orchestratorToolsLog.Printf("Effective markdown after stripping sub-agent sections: %d bytes", len(effectiveMarkdown))
-	if len(subAgents) > 0 {
-		fmt.Fprintln(os.Stderr, console.FormatWarningMessage("Using experimental feature: inline-sub-agents"))
-		c.IncrementWarningCount()
-	}
-
+	orchestratorToolsLog.Printf("Extracted inline sub-agents: count=%d", len(subAgents))
 	// Surface best-effort sub-agent frontmatter warnings collected during import BFS traversal.
 	for _, w := range importsResult.Warnings {
 		fmt.Fprintln(os.Stderr, console.FormatWarningMessage(w))

pkg/workflow/compiler_types.go

@@ -523,6 +523,7 @@ type WorkflowData struct {
 	ActionMode                     ActionMode                      // action mode for workflow compilation (dev, release, script)
 	HasExplicitGitHubTool          bool                            // true if tools.github was explicitly configured in frontmatter
 	InlinedImports                 bool                            // if true, inline all imports at compile time (from inlined-imports frontmatter field)
+	InlineSubAgentsDisabled        bool                            // true when inline-sub-agents: false is set in frontmatter (rejected at compile time)
 	CheckoutConfigs                []*CheckoutConfig               // user-configured checkout settings from frontmatter
 	CheckoutDisabled               bool                            // true when checkout: false is set in frontmatter
 	HasDispatchItemNumber          bool                            // true when workflow_dispatch has item_number input (generated by label trigger shorthand)

pkg/workflow/compiler_validators.go

@@ -55,6 +55,12 @@ func (c *Compiler) validateFeatureConfig(workflowData *WorkflowData, markdownPat
 		return formatCompilerError(markdownPath, "error", err.Error(), err)
 	}
 
+	// Inline sub-agents are always enabled and can no longer be disabled.
+	if workflowData.InlineSubAgentsDisabled {
+		msg := "inline-sub-agents: false is not supported. Inline sub-agents are always enabled. Remove inline-sub-agents from your frontmatter."
+		return formatCompilerError(markdownPath, "error", msg, errors.New("inline-sub-agents cannot be set to false"))
+	}
+
 	// Check for action-mode feature flag override
 	if workflowData.Features != nil {
 		if actionModeVal, exists := workflowData.Features["action-mode"]; exists {

pkg/workflow/compiler_validators_test.go

@@ -67,33 +67,38 @@ func TestValidateFeatureConfig(t *testing.T) {
 	tests := []struct {
 		name          string
 		features      map[string]any
+		inlineDisable bool
 		shouldError   bool
 		errorContains string
 	}{
 		{
-			name:        "no features",
-			features:    nil,
-			shouldError: false,
+			name:          "no features",
+			features:      nil,
+			inlineDisable: false,
+			shouldError:   false,
 		},
 		{
 			name: "valid action-mode dev",
 			features: map[string]any{
 				"action-mode": "dev",
 			},
-			shouldError: false,
+			inlineDisable: false,
+			shouldError:   false,
 		},
 		{
 			name: "valid action-mode release",
 			features: map[string]any{
 				"action-mode": "release",
 			},
-			shouldError: false,
+			inlineDisable: false,
+			shouldError:   false,
 		},
 		{
 			name: "invalid action-mode",
 			features: map[string]any{
 				"action-mode": "invalid-mode",
 			},
+			inlineDisable: false,
 			shouldError:   true,
 			errorContains: "invalid action-mode feature flag",
 		},
@@ -102,7 +107,15 @@ func TestValidateFeatureConfig(t *testing.T) {
 			features: map[string]any{
 				"action-mode": "",
 			},
-			shouldError: false,
+			inlineDisable: false,
+			shouldError:   false,
+		},
+		{
+			name:          "inline-sub-agents false is rejected",
+			features:      nil,
+			inlineDisable: true,
+			shouldError:   true,
+			errorContains: "inline-sub-agents: false is not supported",
 		},
 	}
 
@@ -113,10 +126,11 @@ func TestValidateFeatureConfig(t *testing.T) {
 
 			compiler := NewCompiler()
 			workflowData := &WorkflowData{
-				Name:            "Test",
-				MarkdownContent: "# Test",
-				AI:              "copilot",
-				Features:        tt.features,
+				Name:                    "Test",
+				MarkdownContent:         "# Test",
+				AI:                      "copilot",
+				Features:                tt.features,
+				InlineSubAgentsDisabled: tt.inlineDisable,
 			}
 
 			err := compiler.validateFeatureConfig(workflowData, markdownPath)

pkg/workflow/frontmatter_serialization.go

@@ -162,6 +162,9 @@ func (fc *FrontmatterConfig) ToMap() map[string]any {
 	if fc.Features != nil {
 		result["features"] = fc.Features
 	}
+	if fc.InlineSubAgents != nil {
+		result["inline-sub-agents"] = *fc.InlineSubAgents
+	}
 	if fc.Env != nil {
 		result["env"] = fc.Env
 	}

pkg/workflow/frontmatter_types.go

@@ -274,9 +274,12 @@ type FrontmatterConfig struct {
 	Sandbox *SandboxConfig      `json:"sandbox,omitempty"`
 
 	// Feature flags and other settings
-	Features map[string]any    `json:"features,omitempty"` // Dynamic feature flags
-	Env      map[string]string `json:"env,omitempty"`
-	Secrets  map[string]any    `json:"secrets,omitempty"`
+	Features map[string]any `json:"features,omitempty"` // Dynamic feature flags
+	// Deprecated: as of v1.1.0, inline sub-agents are always enabled.
+	// Remove this field from frontmatter. Setting false causes a compilation error.
+	InlineSubAgents *bool             `json:"inline-sub-agents,omitempty"`
+	Env             map[string]string `json:"env,omitempty"`
+	Secrets         map[string]any    `json:"secrets,omitempty"`
 
 	// Workflow execution settings
 	RunsOn        string         `json:"runs-on,omitempty"`

pkg/workflow/frontmatter_types_test.go

@@ -52,6 +52,24 @@ func TestParseFrontmatterConfig(t *testing.T) {
 		}
 	})
 
+	t.Run("parses inline-sub-agents boolean", func(t *testing.T) {
+		frontmatter := map[string]any{
+			"inline-sub-agents": false,
+		}
+
+		config, err := ParseFrontmatterConfig(frontmatter)
+		if err != nil {
+			t.Fatalf("unexpected error: %v", err)
+		}
+
+		if config.InlineSubAgents == nil {
+			t.Fatal("InlineSubAgents should not be nil")
+		}
+		if *config.InlineSubAgents {
+			t.Error("InlineSubAgents should be false")
+		}
+	})
+
 	t.Run("parses complete workflow config", func(t *testing.T) {
 		frontmatter := map[string]any{
 			"name":        "full-workflow",

pkg/workflow/workflow_builder.go

@@ -121,6 +121,17 @@ func (c *Compiler) buildInitialWorkflowData(
 		}
 	}
 
+	// Populate inline-sub-agents disable flag: explicit false is rejected during validation.
+	if toolsResult.parsedFrontmatter != nil && toolsResult.parsedFrontmatter.InlineSubAgents != nil {
+		workflowData.InlineSubAgentsDisabled = !*toolsResult.parsedFrontmatter.InlineSubAgents
+	} else if rawVal, ok := result.Frontmatter["inline-sub-agents"]; ok {
+		// Fall back to raw frontmatter parsing when full ParseFrontmatterConfig fails
+		// (e.g. due to unrecognized config shapes in other frontmatter sections).
+		if boolVal, ok := rawVal.(bool); ok {
+			workflowData.InlineSubAgentsDisabled = !boolVal
+		}
+	}
+
 	// Populate stale-check flag: disabled when on.stale-check: false is set in frontmatter.
 	if onVal, ok := result.Frontmatter["on"]; ok {
 		if onMap, ok := onVal.(map[string]any); ok {