diff --git a/pkg/cli/codemod_allowed_repos_current_test.go b/pkg/cli/codemod_allowed_repos_current_test.go
index 89d44958c3b..c061db8eeb4 100644
--- a/pkg/cli/codemod_allowed_repos_current_test.go
+++ b/pkg/cli/codemod_allowed_repos_current_test.go
@@ -10,9 +10,11 @@ import (
 )
 
 func TestAllowedReposCurrentToGitHubRepositoryCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getAllowedReposCurrentToGitHubRepositoryCodemod()
 
 	t.Run("metadata is populated", func(t *testing.T) {
+		t.Parallel()
 		assert.Equal(t, "allowed-repos-current-to-github-repository", codemod.ID)
 		assert.NotEmpty(t, codemod.Name)
 		assert.NotEmpty(t, codemod.Description)
@@ -21,6 +23,7 @@ func TestAllowedReposCurrentToGitHubRepositoryCodemod(t *testing.T) {
 	})
 
 	t.Run("rewrites unquoted current value", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -49,6 +52,7 @@ tools:
 	})
 
 	t.Run("rewrites quoted current value", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -74,6 +78,7 @@ tools:
 	})
 
 	t.Run("rewrites single-quoted current value", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -99,6 +104,7 @@ tools:
 	})
 
 	t.Run("no-op when allowed-repos is already an expression", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -124,6 +130,7 @@ tools:
 	})
 
 	t.Run("no-op when allowed-repos is an array", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -150,6 +157,7 @@ tools:
 	})
 
 	t.Run("no-op when allowed-repos is set to all", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -175,6 +183,7 @@ tools:
 	})
 
 	t.Run("preserves trailing comments", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -200,6 +209,7 @@ tools:
 	})
 
 	t.Run("only treats whitespace-preceded hash as a comment marker", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -225,6 +235,7 @@ tools:
 	})
 
 	t.Run("does not rewrite nested non-top-level tools github allowed-repos", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 wrapper:
@@ -262,6 +273,7 @@ tools:
 	})
 
 	t.Run("does not rewrite nested custom github allowed-repos", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
diff --git a/pkg/cli/codemod_assign_to_agent_test.go b/pkg/cli/codemod_assign_to_agent_test.go
index 40534f605fa..c15c561aa40 100644
--- a/pkg/cli/codemod_assign_to_agent_test.go
+++ b/pkg/cli/codemod_assign_to_agent_test.go
@@ -10,6 +10,7 @@ import (
 )
 
 func TestGetAssignToAgentDefaultAgentCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	assert.Equal(t, "assign-to-agent-default-agent-to-name", codemod.ID)
@@ -20,6 +21,7 @@ func TestGetAssignToAgentDefaultAgentCodemod(t *testing.T) {
 }
 
 func TestAssignToAgentCodemod_BasicMigration(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	content := `---
@@ -51,6 +53,7 @@ safe-outputs:
 }
 
 func TestAssignToAgentCodemod_PreservesIndentation(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	content := `---
@@ -82,6 +85,7 @@ safe-outputs:
 }
 
 func TestAssignToAgentCodemod_PreservesComment(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	content := `---
@@ -109,6 +113,7 @@ safe-outputs:
 }
 
 func TestAssignToAgentCodemod_NoSafeOutputs(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	content := `---
@@ -131,6 +136,7 @@ engine: copilot
 }
 
 func TestAssignToAgentCodemod_NoAssignToAgent(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	content := `---
@@ -158,6 +164,7 @@ safe-outputs:
 }
 
 func TestAssignToAgentCodemod_NoDefaultAgent(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	content := `---
@@ -185,6 +192,7 @@ safe-outputs:
 }
 
 func TestAssignToAgentCodemod_SkipsWhenNameAlreadyExists(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	content := `---
@@ -214,6 +222,7 @@ safe-outputs:
 }
 
 func TestAssignToAgentCodemod_PreservesOtherSafeOutputs(t *testing.T) {
+	t.Parallel()
 	codemod := getAssignToAgentDefaultAgentCodemod()
 
 	content := `---
@@ -248,6 +257,7 @@ safe-outputs:
 }
 
 func TestAssignToAgentCodemod_RegisteredInAllCodemods(t *testing.T) {
+	t.Parallel()
 	codemods := GetAllCodemods()
 	var found bool
 	for _, c := range codemods {
diff --git a/pkg/cli/codemod_bash_allowlist_unsupported_engine_test.go b/pkg/cli/codemod_bash_allowlist_unsupported_engine_test.go
index 9eed4e52e1e..093cd23b232 100644
--- a/pkg/cli/codemod_bash_allowlist_unsupported_engine_test.go
+++ b/pkg/cli/codemod_bash_allowlist_unsupported_engine_test.go
@@ -12,6 +12,7 @@ import (
 )
 
 func TestBashAllowlistUnsupportedEngineCodemod_Metadata(t *testing.T) {
+	t.Parallel()
 	codemod := getBashAllowlistUnsupportedEngineCodemod()
 
 	assert.Equal(t, "bash-allowlist-unsupported-engine-guided-error", codemod.ID)
@@ -24,6 +25,7 @@ func TestBashAllowlistUnsupportedEngineCodemod_Metadata(t *testing.T) {
 }
 
 func TestBashAllowlistUnsupportedEngineCodemod_Apply(t *testing.T) {
+	t.Parallel()
 	codemod := getBashAllowlistUnsupportedEngineCodemod()
 
 	content := `---
@@ -150,6 +152,7 @@ tools:
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			newContent, applied, err := codemod.Apply(content, tt.frontmatter)
 			assert.False(t, applied, "guided codemod never modifies the workflow")
 			assert.Equal(t, content, newContent, "content must be preserved")
@@ -169,6 +172,7 @@ tools:
 // ApplyWithContext detects a bash restriction that originates solely from an imported file (not
 // the top-level workflow), which Apply cannot detect because it only sees raw frontmatter.
 func TestBashAllowlistUnsupportedEngineCodemod_ApplyWithContext_ImportedRestriction(t *testing.T) {
+	t.Parallel()
 	codemod := getBashAllowlistUnsupportedEngineCodemod()
 
 	dir := t.TempDir()
@@ -210,6 +214,7 @@ imports:
 // TestBashAllowlistUnsupportedEngineCodemod_ApplyWithContext_NoImportedRestriction verifies that
 // ApplyWithContext is a no-op when no bash restriction exists in the top-level or imported tools.
 func TestBashAllowlistUnsupportedEngineCodemod_ApplyWithContext_NoImportedRestriction(t *testing.T) {
+	t.Parallel()
 	codemod := getBashAllowlistUnsupportedEngineCodemod()
 
 	content := `---
diff --git a/pkg/cli/codemod_bash_anonymous_test.go b/pkg/cli/codemod_bash_anonymous_test.go
index bc80df91f13..e02d122d965 100644
--- a/pkg/cli/codemod_bash_anonymous_test.go
+++ b/pkg/cli/codemod_bash_anonymous_test.go
@@ -12,6 +12,7 @@ import (
 )
 
 func TestBashAnonymousRemovalCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getBashAnonymousRemovalCodemod()
 
 	tests := []struct {
@@ -86,6 +87,7 @@ name: Test Workflow
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			// Parse frontmatter to get the map
 			result, err := parser.ExtractFrontmatterFromContent(tt.input)
 			require.NoError(t, err, "Failed to parse test input frontmatter")
@@ -118,6 +120,7 @@ name: Test Workflow
 }
 
 func TestBashAnonymousCodemodWithComments(t *testing.T) {
+	t.Parallel()
 	codemod := getBashAnonymousRemovalCodemod()
 
 	input := `---
@@ -140,6 +143,7 @@ tools:
 }
 
 func TestBashAnonymousCodemodPreservesIndentation(t *testing.T) {
+	t.Parallel()
 	codemod := getBashAnonymousRemovalCodemod()
 
 	input := `---
@@ -172,6 +176,7 @@ tools:
 }
 
 func TestReplaceBashAnonymousWithTrue(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name        string
 		lines       []string
@@ -230,6 +235,7 @@ func TestReplaceBashAnonymousWithTrue(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			result, modified := replaceBashAnonymousWithTrue(tt.lines)
 			assert.Equal(t, tt.modified, modified, "Modified status mismatch")
 			assert.Equal(t, tt.expectLines, result, "Output lines mismatch")
diff --git a/pkg/cli/codemod_bash_single_quoted_args_test.go b/pkg/cli/codemod_bash_single_quoted_args_test.go
index 5f08b7321e7..56714dc19a6 100644
--- a/pkg/cli/codemod_bash_single_quoted_args_test.go
+++ b/pkg/cli/codemod_bash_single_quoted_args_test.go
@@ -11,6 +11,7 @@ import (
 )
 
 func TestGetBashSingleQuotedArgsCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getBashSingleQuotedArgsCodemod()
 
 	assert.Equal(t, "bash-single-quoted-args-rewrite", codemod.ID)
@@ -21,6 +22,7 @@ func TestGetBashSingleQuotedArgsCodemod(t *testing.T) {
 }
 
 func TestBashSingleQuotedArgsCodemod_RewritesSimpleSingleQuotedArg(t *testing.T) {
+	t.Parallel()
 	codemod := getBashSingleQuotedArgsCodemod()
 	content := `---
 name: test
@@ -50,6 +52,7 @@ Test workflow body`
 }
 
 func TestBashSingleQuotedArgsCodemod_RewritesGlobPatterns(t *testing.T) {
+	t.Parallel()
 	codemod := getBashSingleQuotedArgsCodemod()
 	content := `---
 name: test
@@ -78,6 +81,7 @@ body`
 }
 
 func TestBashSingleQuotedArgsCodemod_NoOpForAlreadySafeEntry(t *testing.T) {
+	t.Parallel()
 	codemod := getBashSingleQuotedArgsCodemod()
 	content := `---
 name: test
@@ -101,6 +105,7 @@ body`
 }
 
 func TestBashSingleQuotedArgsCodemod_UnmatchedQuoteLeftUnchanged(t *testing.T) {
+	t.Parallel()
 	codemod := getBashSingleQuotedArgsCodemod()
 	content := `---
 name: test
@@ -124,6 +129,7 @@ body`
 }
 
 func TestRewriteSingleQuotedBashArgs(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name      string
 		input     string
@@ -184,6 +190,7 @@ func TestRewriteSingleQuotedBashArgs(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			got, safe, changed := rewriteSingleQuotedBashArgs(tt.input)
 			assert.Equal(t, tt.want, got)
 			assert.Equal(t, tt.wantSafe, safe)
diff --git a/pkg/cli/codemod_bots_test.go b/pkg/cli/codemod_bots_test.go
index cfc534b1213..8878724799c 100644
--- a/pkg/cli/codemod_bots_test.go
+++ b/pkg/cli/codemod_bots_test.go
@@ -12,6 +12,7 @@ import (
 )
 
 func TestGetBotsToOnBotsCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getBotsToOnBotsCodemod()
 
 	assert.Equal(t, "bots-to-on-bots", codemod.ID)
@@ -22,6 +23,7 @@ func TestGetBotsToOnBotsCodemod(t *testing.T) {
 }
 
 func TestBotsToOnBotsCodemod_SingleLineArray(t *testing.T) {
+	t.Parallel()
 	codemod := getBotsToOnBotsCodemod()
 
 	content := `---
@@ -68,6 +70,7 @@ bots: [dependabot, renovate]
 }
 
 func TestBotsToOnBotsCodemod_MultiLineArray(t *testing.T) {
+	t.Parallel()
 	codemod := getBotsToOnBotsCodemod()
 
 	content := `---
@@ -103,6 +106,7 @@ bots:
 }
 
 func TestBotsToOnBotsCodemod_NoOnBlock(t *testing.T) {
+	t.Parallel()
 	codemod := getBotsToOnBotsCodemod()
 
 	content := `---
@@ -130,6 +134,7 @@ engine: copilot
 }
 
 func TestBotsToOnBotsCodemod_NoChange_NoBots(t *testing.T) {
+	t.Parallel()
 	codemod := getBotsToOnBotsCodemod()
 
 	content := `---
@@ -158,6 +163,7 @@ engine: copilot
 }
 
 func TestBotsToOnBotsCodemod_NoChange_OnBotsExists(t *testing.T) {
+	t.Parallel()
 	codemod := getBotsToOnBotsCodemod()
 
 	content := `---
diff --git a/pkg/cli/codemod_byok_copilot_test.go b/pkg/cli/codemod_byok_copilot_test.go
index 904e32060b5..2c88d714c66 100644
--- a/pkg/cli/codemod_byok_copilot_test.go
+++ b/pkg/cli/codemod_byok_copilot_test.go
@@ -11,6 +11,7 @@ import (
 )
 
 func TestByokCopilotFeatureRemovalCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getByokCopilotFeatureRemovalCodemod()
 
 	tests := []struct {
@@ -56,6 +57,7 @@ features:
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			result, err := parser.ExtractFrontmatterFromContent(tt.input)
 			require.NoError(t, err, "Failed to parse test input frontmatter")
 
diff --git a/pkg/cli/codemod_checkout_persist_credentials_false_test.go b/pkg/cli/codemod_checkout_persist_credentials_false_test.go
index 33505b399e0..4e9b28b59a0 100644
--- a/pkg/cli/codemod_checkout_persist_credentials_false_test.go
+++ b/pkg/cli/codemod_checkout_persist_credentials_false_test.go
@@ -11,10 +11,12 @@ import (
 )
 
 func TestCheckoutPersistCredentialsFalseCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getCheckoutPersistCredentialsFalseCodemod()
 	assert.Equal(t, "1.0.44", codemod.IntroducedIn)
 
 	t.Run("adds with block when checkout step has none", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: push
 steps:
@@ -39,6 +41,7 @@ steps:
 	})
 
 	t.Run("adds persist-credentials under existing with block", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: push
 steps:
@@ -68,6 +71,7 @@ steps:
 	})
 
 	t.Run("does not mutate explicit persist-credentials true", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: push
 steps:
@@ -97,6 +101,7 @@ steps:
 	})
 
 	t.Run("supports pre-steps and post-steps sections", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: pull_request
 pre-steps:
@@ -127,6 +132,7 @@ post-steps:
 	})
 
 	t.Run("applies to jobs.agent but not custom jobs", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 jobs:
@@ -163,6 +169,7 @@ jobs:
 	})
 
 	t.Run("applies to jobs.agent with wider indentation", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 jobs:
@@ -189,6 +196,7 @@ jobs:
 	})
 
 	t.Run("does not apply to checkout in non-agent custom job only", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 jobs:
diff --git a/pkg/cli/codemod_cli_proxy_mode_test.go b/pkg/cli/codemod_cli_proxy_mode_test.go
index 1d32fa440d9..a05a898652d 100644
--- a/pkg/cli/codemod_cli_proxy_mode_test.go
+++ b/pkg/cli/codemod_cli_proxy_mode_test.go
@@ -10,9 +10,11 @@ import (
 )
 
 func TestCliProxyFeatureToGitHubModeCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getCliProxyFeatureToGitHubModeCodemod()
 
 	t.Run("migrates features.cli-proxy true and adds tools.github.mode gh-proxy", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   cli-proxy: true
@@ -36,6 +38,7 @@ features:
 	})
 
 	t.Run("does not apply when cli-proxy is false", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   cli-proxy: false
@@ -56,6 +59,7 @@ features:
 	})
 
 	t.Run("removes legacy flag but preserves existing github mode", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   cli-proxy: true
@@ -86,6 +90,7 @@ tools:
 	})
 
 	t.Run("adds github block under existing tools block", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   cli-proxy: true
diff --git a/pkg/cli/codemod_copilot_requests_feature_test.go b/pkg/cli/codemod_copilot_requests_feature_test.go
index cab98d0974e..cceab93cefe 100644
--- a/pkg/cli/codemod_copilot_requests_feature_test.go
+++ b/pkg/cli/codemod_copilot_requests_feature_test.go
@@ -10,9 +10,11 @@ import (
 )
 
 func TestCopilotRequestsFeatureToPermissionsCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getCopilotRequestsFeatureToPermissionsCodemod()
 
 	t.Run("migrates enabled feature to permissions", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   copilot-requests: true
@@ -39,6 +41,7 @@ permissions:
 	})
 
 	t.Run("adds permissions block when missing", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   copilot-requests: true
@@ -65,6 +68,7 @@ on:
 	})
 
 	t.Run("removes disabled feature without adding permission", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   copilot-requests: false
@@ -86,6 +90,7 @@ features:
 	})
 
 	t.Run("skips migration when permissions shorthand is not safely updatable", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   copilot-requests: true
@@ -108,6 +113,7 @@ permissions: read-all
 	})
 
 	t.Run("handles empty permissions object with inline comment", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 features:
   copilot-requests: true
diff --git a/pkg/cli/codemod_dependabot_permissions_test.go b/pkg/cli/codemod_dependabot_permissions_test.go
index d25f6b92729..59c9ac5071d 100644
--- a/pkg/cli/codemod_dependabot_permissions_test.go
+++ b/pkg/cli/codemod_dependabot_permissions_test.go
@@ -10,9 +10,11 @@ import (
 )
 
 func TestDependabotPermissionsCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getDependabotPermissionsCodemod()
 
 	t.Run("adds missing vulnerability-alerts permission", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on:
   workflow_dispatch:
@@ -44,6 +46,7 @@ permissions:
 	})
 
 	t.Run("adds missing issues permission for issues toolset", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on:
   workflow_dispatch:
@@ -75,6 +78,7 @@ permissions:
 	})
 
 	t.Run("does not modify when permission already present", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 tools:
   github:
diff --git a/pkg/cli/codemod_difc_proxy_test.go b/pkg/cli/codemod_difc_proxy_test.go
index bf6bad32968..a66f00be914 100644
--- a/pkg/cli/codemod_difc_proxy_test.go
+++ b/pkg/cli/codemod_difc_proxy_test.go
@@ -10,9 +10,11 @@ import (
 )
 
 func TestDIFCProxyToIntegrityProxyCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getDIFCProxyToIntegrityProxyCodemod()
 
 	t.Run("removes features.difc-proxy: true (no-op since proxy is now default)", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 features:
@@ -45,6 +47,7 @@ tools:
 	})
 
 	t.Run("removes features.difc-proxy: false and adds tools.github.integrity-proxy: false", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 features:
@@ -77,6 +80,7 @@ tools:
 	})
 
 	t.Run("removes features.difc-proxy: false but does NOT add integrity-proxy when tools.github is absent", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 features:
@@ -100,6 +104,7 @@ features:
 	})
 
 	t.Run("removes features.difc-proxy: false but does NOT add integrity-proxy when tools.github is boolean true", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 features:
@@ -128,6 +133,7 @@ tools:
 	})
 
 	t.Run("does not modify workflows without features.difc-proxy", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 tools:
@@ -153,6 +159,7 @@ tools:
 	})
 
 	t.Run("does not modify workflows without features section", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 ---
@@ -170,6 +177,7 @@ engine: copilot
 	})
 
 	t.Run("preserves other features when removing difc-proxy", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 features:
@@ -203,6 +211,7 @@ tools:
 	})
 
 	t.Run("integrity-proxy: false is added inside tools.github block", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 features:
@@ -244,6 +253,7 @@ tools:
 	})
 
 	t.Run("string 'false' value treated as false (adds integrity-proxy: false)", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 features:
diff --git a/pkg/cli/codemod_discussion_flag_test.go b/pkg/cli/codemod_discussion_flag_test.go
index 5d52b289a48..ebf66684b66 100644
--- a/pkg/cli/codemod_discussion_flag_test.go
+++ b/pkg/cli/codemod_discussion_flag_test.go
@@ -10,6 +10,7 @@ import (
 )
 
 func TestGetDiscussionFlagRemovalCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	assert.Equal(t, "add-comment-discussion-removal", codemod.ID)
@@ -20,6 +21,7 @@ func TestGetDiscussionFlagRemovalCodemod(t *testing.T) {
 }
 
 func TestDiscussionFlagCodemod_RemovesDiscussionFlag(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	content := `---
@@ -60,6 +62,7 @@ safe-outputs:
 }
 
 func TestDiscussionFlagCodemod_NoSafeOutputsField(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	content := `---
@@ -85,6 +88,7 @@ permissions:
 }
 
 func TestDiscussionFlagCodemod_NoAddCommentField(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	content := `---
@@ -113,6 +117,7 @@ safe-outputs:
 }
 
 func TestDiscussionFlagCodemod_NoDiscussionField(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	content := `---
@@ -143,6 +148,7 @@ safe-outputs:
 }
 
 func TestDiscussionFlagCodemod_PreservesIndentation(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	content := `---
@@ -183,6 +189,7 @@ safe-outputs:
 }
 
 func TestDiscussionFlagCodemod_PreservesComments(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	content := `---
@@ -217,6 +224,7 @@ safe-outputs:
 }
 
 func TestDiscussionFlagCodemod_PreservesMarkdown(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	content := `---
@@ -248,6 +256,7 @@ This workflow uses add-comment with discussion support.`
 }
 
 func TestDiscussionFlagCodemod_MultipleFields(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionFlagRemovalCodemod()
 
 	content := `---
diff --git a/pkg/cli/codemod_discussion_trigger_categories_test.go b/pkg/cli/codemod_discussion_trigger_categories_test.go
index 207c21ad5cd..cceb264f39e 100644
--- a/pkg/cli/codemod_discussion_trigger_categories_test.go
+++ b/pkg/cli/codemod_discussion_trigger_categories_test.go
@@ -10,6 +10,7 @@ import (
 )
 
 func TestGetDiscussionTriggerCategoriesLowercaseCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionTriggerCategoriesLowercaseCodemod()
 
 	assert.Equal(t, "discussion-trigger-categories-lowercase", codemod.ID)
@@ -20,6 +21,7 @@ func TestGetDiscussionTriggerCategoriesLowercaseCodemod(t *testing.T) {
 }
 
 func TestDiscussionTriggerCategoriesCodemod_LowercasesMixedCaseValues(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionTriggerCategoriesLowercaseCodemod()
 
 	content := `---
@@ -55,6 +57,7 @@ on:
 }
 
 func TestDiscussionTriggerCategoriesCodemod_NoOpWhenAlreadyLowercase(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionTriggerCategoriesLowercaseCodemod()
 
 	content := `---
@@ -87,6 +90,7 @@ on:
 }
 
 func TestDiscussionTriggerCategoriesCodemod_LowercasesQuotedOnAndTriggerKeys(t *testing.T) {
+	t.Parallel()
 	codemod := getDiscussionTriggerCategoriesLowercaseCodemod()
 
 	content := `---
@@ -122,6 +126,7 @@ func TestDiscussionTriggerCategoriesCodemod_LowercasesQuotedOnAndTriggerKeys(t *
 }
 
 func TestGetBlockMappingKey(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name    string
 		line    string
@@ -137,6 +142,7 @@ func TestGetBlockMappingKey(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			gotKey, gotOK := getBlockMappingKey(tt.line)
 			assert.Equal(t, tt.wantKey, gotKey)
 			assert.Equal(t, tt.wantOK, gotOK)
diff --git a/pkg/cli/codemod_effective_tokens_to_ai_credits_test.go b/pkg/cli/codemod_effective_tokens_to_ai_credits_test.go
index 616255b21b7..4e0fa7100a1 100644
--- a/pkg/cli/codemod_effective_tokens_to_ai_credits_test.go
+++ b/pkg/cli/codemod_effective_tokens_to_ai_credits_test.go
@@ -10,6 +10,7 @@ import (
 )
 
 func TestGetEffectiveTokensToAICreditsCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	assert.Equal(t, "effective-tokens-to-ai-credits", codemod.ID)
@@ -20,6 +21,7 @@ func TestGetEffectiveTokensToAICreditsCodemod(t *testing.T) {
 }
 
 func TestEffectiveTokensToAICreditsCodemod_MigratesNumericValues(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -47,6 +49,7 @@ on: workflow_dispatch
 }
 
 func TestEffectiveTokensToAICreditsCodemod_NoOpWhenLegacyFieldsAbsent(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -66,6 +69,7 @@ max-daily-ai-credits: 5000
 }
 
 func TestEffectiveTokensToAICreditsCodemod_IdempotentAfterMigration(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -85,6 +89,7 @@ max-daily-ai-credits: 1
 }
 
 func TestEffectiveTokensToAICreditsCodemod_SkipsExpressionValues(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -106,6 +111,7 @@ max-daily-effective-tokens: 4M
 }
 
 func TestEffectiveTokensToAICreditsCodemod_SkipsWhenTargetFieldExists(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -125,6 +131,7 @@ max-ai-credits: 2500
 }
 
 func TestEffectiveTokensToAICreditsCodemod_MigratesDailyNegativeOne(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -143,6 +150,7 @@ max-daily-effective-tokens: -1 # disabled
 }
 
 func TestEffectiveTokensToAICreditsCodemod_MigratesRunNegativeOne(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -161,6 +169,7 @@ max-effective-tokens: -1 # disabled
 }
 
 func TestEffectiveTokensToAICreditsCodemod_SkipsValuesBelowOneCredit(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -180,6 +189,7 @@ max-daily-effective-tokens: 5000
 }
 
 func TestEffectiveTokensToAICreditsCodemod_PartialMigrationWhenOnlyOneValueConverts(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -201,6 +211,7 @@ max-daily-effective-tokens: 10k
 }
 
 func TestEffectiveTokensToAICreditsCodemod_PartialMigrationWhenOnlyRunValueConverts(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
@@ -222,6 +233,7 @@ max-daily-effective-tokens: 5000
 }
 
 func TestEffectiveTokensToAICreditsCodemod_MigratesThresholdValue(t *testing.T) {
+	t.Parallel()
 	codemod := getEffectiveTokensToAICreditsCodemod()
 
 	content := `---
diff --git a/pkg/cli/codemod_engine_driver_test.go b/pkg/cli/codemod_engine_driver_test.go
index 96c173e2e42..1e3a8982927 100644
--- a/pkg/cli/codemod_engine_driver_test.go
+++ b/pkg/cli/codemod_engine_driver_test.go
@@ -10,9 +10,11 @@ import (
 )
 
 func TestEngineCopilotSDKDriverToDriverCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineCopilotSDKDriverToDriverCodemod()
 
 	t.Run("renames copilot-sdk-driver to driver in engine block", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine:
   id: copilot
@@ -36,6 +38,7 @@ engine:
 	})
 
 	t.Run("does not apply when engine has no copilot-sdk-driver field", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine:
   id: copilot
@@ -56,6 +59,7 @@ engine:
 	})
 
 	t.Run("does not apply when driver field already present", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine:
   id: copilot
@@ -80,6 +84,7 @@ engine:
 	})
 
 	t.Run("does not apply when no engine block", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 name: My Workflow
 ---
@@ -97,6 +102,7 @@ name: My Workflow
 	})
 
 	t.Run("does not apply when engine is a scalar", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine: copilot
 ---
@@ -114,6 +120,7 @@ engine: copilot
 	})
 
 	t.Run("preserves indentation when renaming", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine:
   id: copilot
diff --git a/pkg/cli/codemod_engine_env_secrets_test.go b/pkg/cli/codemod_engine_env_secrets_test.go
index 4a88e6d03c4..be1c6c7d1e1 100644
--- a/pkg/cli/codemod_engine_env_secrets_test.go
+++ b/pkg/cli/codemod_engine_env_secrets_test.go
@@ -10,9 +10,11 @@ import (
 )
 
 func TestEngineEnvSecretsCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineEnvSecretsCodemod()
 
 	t.Run("removes unsafe secret-bearing engine env keys and keeps allowed override", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 engine:
@@ -41,6 +43,7 @@ engine:
 	})
 
 	t.Run("removes empty env block after deleting unsafe entries", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 engine:
@@ -67,6 +70,7 @@ engine:
 	})
 
 	t.Run("no-op when only allowed engine secret override is used", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 engine:
@@ -92,6 +96,7 @@ engine:
 	})
 
 	t.Run("no-op when COPILOT_PROVIDER_API_KEY is used (BYOK)", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 engine:
@@ -121,6 +126,7 @@ engine:
 	})
 
 	t.Run("no-op when COPILOT_PROVIDER_BEARER_TOKEN is used (BYOK)", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 engine:
@@ -148,6 +154,7 @@ engine:
 	})
 
 	t.Run("supports inline engine runtime.id for allowlist", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 on: workflow_dispatch
 engine:
diff --git a/pkg/cli/codemod_engine_max_runs_test.go b/pkg/cli/codemod_engine_max_runs_test.go
index 78966475870..fd37220e0ae 100644
--- a/pkg/cli/codemod_engine_max_runs_test.go
+++ b/pkg/cli/codemod_engine_max_runs_test.go
@@ -10,6 +10,7 @@ import (
 )
 
 func TestEngineMaxRunsToTopLevelCodemod_Metadata(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxRunsToTopLevelCodemod()
 
 	assert.Equal(t, "engine-max-runs-to-top-level", codemod.ID)
@@ -20,6 +21,7 @@ func TestEngineMaxRunsToTopLevelCodemod_Metadata(t *testing.T) {
 }
 
 func TestEngineMaxRunsToTopLevelCodemod_NoOp(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxRunsToTopLevelCodemod()
 
 	content := `---
@@ -42,6 +44,7 @@ engine:
 }
 
 func TestEngineMaxRunsToTopLevelCodemod_MigratesField(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxRunsToTopLevelCodemod()
 
 	content := `---
@@ -68,6 +71,7 @@ engine:
 }
 
 func TestEngineMaxRunsToTopLevelCodemod_RespectsExistingTopLevel(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxRunsToTopLevelCodemod()
 
 	content := `---
@@ -94,6 +98,7 @@ engine:
 }
 
 func TestEngineMaxRunsToTopLevelCodemod_InlineEngineMapNoOp(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxRunsToTopLevelCodemod()
 
 	content := `---
diff --git a/pkg/cli/codemod_engine_max_turns_test.go b/pkg/cli/codemod_engine_max_turns_test.go
index 8190edd4950..9abab7e5671 100644
--- a/pkg/cli/codemod_engine_max_turns_test.go
+++ b/pkg/cli/codemod_engine_max_turns_test.go
@@ -10,6 +10,7 @@ import (
 )
 
 func TestEngineMaxTurnsToTopLevelCodemod_Metadata(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxTurnsToTopLevelCodemod()
 
 	assert.Equal(t, "engine-max-turns-to-top-level", codemod.ID)
@@ -20,6 +21,7 @@ func TestEngineMaxTurnsToTopLevelCodemod_Metadata(t *testing.T) {
 }
 
 func TestEngineMaxTurnsToTopLevelCodemod_NoOp(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxTurnsToTopLevelCodemod()
 
 	content := `---
@@ -42,6 +44,7 @@ engine:
 }
 
 func TestEngineMaxTurnsToTopLevelCodemod_IdempotentWhenAlreadyMigrated(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxTurnsToTopLevelCodemod()
 
 	content := `---
@@ -64,6 +67,7 @@ engine:
 }
 
 func TestEngineMaxTurnsToTopLevelCodemod_MigratesField(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxTurnsToTopLevelCodemod()
 
 	content := `---
@@ -98,6 +102,7 @@ engine:
 }
 
 func TestEngineMaxTurnsToTopLevelCodemod_PreservesExpressionCommentsAndBody(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxTurnsToTopLevelCodemod()
 
 	content := `---
@@ -134,6 +139,7 @@ Keep this content.`
 }
 
 func TestEngineMaxTurnsToTopLevelCodemod_RespectsExistingTopLevel(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxTurnsToTopLevelCodemod()
 
 	content := `---
@@ -160,6 +166,7 @@ engine:
 }
 
 func TestEngineMaxTurnsToTopLevelCodemod_InlineEngineMapNoOp(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineMaxTurnsToTopLevelCodemod()
 
 	content := `---
diff --git a/pkg/cli/codemod_engine_model_test.go b/pkg/cli/codemod_engine_model_test.go
index 205e5e9be64..ed2837b66a2 100644
--- a/pkg/cli/codemod_engine_model_test.go
+++ b/pkg/cli/codemod_engine_model_test.go
@@ -10,6 +10,7 @@ import (
 )
 
 func TestEngineModelToTopLevelCodemod_Metadata(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineModelToTopLevelCodemod()
 
 	assert.Equal(t, "engine-model-to-top-level", codemod.ID)
@@ -20,6 +21,7 @@ func TestEngineModelToTopLevelCodemod_Metadata(t *testing.T) {
 }
 
 func TestEngineModelToTopLevelCodemod_NoOp(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineModelToTopLevelCodemod()
 
 	content := `---
@@ -42,6 +44,7 @@ engine:
 }
 
 func TestEngineModelToTopLevelCodemod_IdempotentWhenAlreadyMigrated(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineModelToTopLevelCodemod()
 
 	content := `---
@@ -64,6 +67,7 @@ engine:
 }
 
 func TestEngineModelToTopLevelCodemod_MigratesField(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineModelToTopLevelCodemod()
 
 	content := `---
@@ -98,6 +102,7 @@ engine:
 }
 
 func TestEngineModelToTopLevelCodemod_PreservesCommentsAndBody(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineModelToTopLevelCodemod()
 
 	content := `---
@@ -134,6 +139,7 @@ Keep this content.`
 }
 
 func TestEngineModelToTopLevelCodemod_RespectsExistingTopLevel(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineModelToTopLevelCodemod()
 
 	content := `---
@@ -160,6 +166,7 @@ engine:
 }
 
 func TestEngineModelToTopLevelCodemod_InlineEngineMapNoOp(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineModelToTopLevelCodemod()
 
 	content := `---
diff --git a/pkg/cli/codemod_engine_steps_test.go b/pkg/cli/codemod_engine_steps_test.go
index c66ab40d545..5dd7aa64285 100644
--- a/pkg/cli/codemod_engine_steps_test.go
+++ b/pkg/cli/codemod_engine_steps_test.go
@@ -11,6 +11,7 @@ import (
 )
 
 func TestGetEngineStepsToTopLevelCodemod_Metadata(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	assert.Equal(t, "engine-steps-to-top-level", codemod.ID)
@@ -22,6 +23,7 @@ func TestGetEngineStepsToTopLevelCodemod_Metadata(t *testing.T) {
 
 // TestEngineStepsToTopLevelCodemod_NoOp tests cases where the codemod should not apply
 func TestEngineStepsToTopLevelCodemod_NoOp(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name        string
 		content     string
@@ -73,6 +75,7 @@ engine:
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			codemod := getEngineStepsToTopLevelCodemod()
 			result, applied, err := codemod.Apply(tt.content, tt.frontmatter)
 			require.NoError(t, err)
@@ -84,6 +87,7 @@ engine:
 
 // TestEngineStepsToTopLevelCodemod_SingleStep tests moving a single engine step to top level
 func TestEngineStepsToTopLevelCodemod_SingleStep(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -121,6 +125,7 @@ engine:
 
 // TestEngineStepsToTopLevelCodemod_MultipleSteps tests moving multiple steps preserves order
 func TestEngineStepsToTopLevelCodemod_MultipleSteps(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -183,6 +188,7 @@ engine:
 
 // TestEngineStepsToTopLevelCodemod_UsesStep tests a step that uses an action (not run:)
 func TestEngineStepsToTopLevelCodemod_UsesStep(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -231,6 +237,7 @@ engine:
 // TestEngineStepsToTopLevelCodemod_EngineFieldsAfterSteps tests that engine fields after steps
 // are preserved correctly in the engine block
 func TestEngineStepsToTopLevelCodemod_EngineFieldsAfterSteps(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -270,6 +277,7 @@ engine:
 // TestEngineStepsToTopLevelCodemod_MergeWithExistingSteps tests appending engine steps
 // after existing top-level steps
 func TestEngineStepsToTopLevelCodemod_MergeWithExistingSteps(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -325,6 +333,7 @@ steps:
 
 // TestEngineStepsToTopLevelCodemod_NoMarkdownBody tests a workflow without a body section
 func TestEngineStepsToTopLevelCodemod_NoMarkdownBody(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -358,6 +367,7 @@ engine:
 // TestEngineStepsToTopLevelCodemod_Idempotent tests that applying the codemod twice
 // (simulated by running on output with updated frontmatter) does not change the content
 func TestEngineStepsToTopLevelCodemod_Idempotent(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	// After codemod is applied, engine no longer has steps in frontmatter
@@ -393,6 +403,7 @@ steps:
 // TestEngineStepsToTopLevelCodemod_StepsBeforeEngine tests when top-level steps field
 // comes before the engine field in the YAML
 func TestEngineStepsToTopLevelCodemod_StepsBeforeEngine(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -442,6 +453,7 @@ engine:
 // TestEngineStepsToTopLevelCodemod_PreservesMarkdownBody tests that the markdown body
 // is preserved after the frontmatter when applying the codemod
 func TestEngineStepsToTopLevelCodemod_PreservesMarkdownBody(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -488,6 +500,7 @@ Follow these steps carefully.`
 
 // TestEngineStepsToTopLevelCodemod_TableDriven is a comprehensive table-driven test
 func TestEngineStepsToTopLevelCodemod_TableDriven(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name         string
 		content      string
@@ -584,6 +597,7 @@ Review this PR`,
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			codemod := getEngineStepsToTopLevelCodemod()
 			result, applied, err := codemod.Apply(tt.content, tt.frontmatter)
 
@@ -603,6 +617,7 @@ Review this PR`,
 // TestEngineStepsToTopLevelCodemod_EmptyEngineBlockRemoved tests that a dangling
 // engine: block (containing only steps) is removed after migration
 func TestEngineStepsToTopLevelCodemod_EmptyEngineBlockRemoved(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
@@ -639,6 +654,7 @@ engine:
 // TestEngineStepsToTopLevelCodemod_NonSequenceTopLevelSteps tests that when
 // top-level steps exists but is not a sequence, a fresh steps block is inserted
 func TestEngineStepsToTopLevelCodemod_NonSequenceTopLevelSteps(t *testing.T) {
+	t.Parallel()
 	codemod := getEngineStepsToTopLevelCodemod()
 
 	content := `---
diff --git a/pkg/cli/codemod_expires_integer_test.go b/pkg/cli/codemod_expires_integer_test.go
index f5291312ee4..98fca114b16 100644
--- a/pkg/cli/codemod_expires_integer_test.go
+++ b/pkg/cli/codemod_expires_integer_test.go
@@ -10,6 +10,7 @@ import (
 )
 
 func TestGetExpiresIntegerToStringCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	assert.Equal(t, "expires-integer-to-string", codemod.ID)
@@ -20,6 +21,7 @@ func TestGetExpiresIntegerToStringCodemod(t *testing.T) {
 }
 
 func TestExpiresIntegerCodemod_ConvertsCreateIssue(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -48,6 +50,7 @@ safe-outputs:
 }
 
 func TestExpiresIntegerCodemod_ConvertsCreateDiscussion(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -76,6 +79,7 @@ safe-outputs:
 }
 
 func TestExpiresIntegerCodemod_ConvertsCreatePullRequest(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -104,6 +108,7 @@ safe-outputs:
 }
 
 func TestExpiresIntegerCodemod_AlreadyStringFormat_NoChange(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -132,6 +137,7 @@ safe-outputs:
 }
 
 func TestExpiresIntegerCodemod_HourStringFormat_NoChange(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -160,6 +166,7 @@ safe-outputs:
 }
 
 func TestExpiresIntegerCodemod_NoSafeOutputs_NoChange(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -185,6 +192,7 @@ permissions:
 }
 
 func TestExpiresIntegerCodemod_PreservesComment(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -213,6 +221,7 @@ safe-outputs:
 }
 
 func TestExpiresIntegerCodemod_PreservesOtherFields(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -248,6 +257,7 @@ safe-outputs:
 }
 
 func TestExpiresIntegerCodemod_MultipleOutputTypes(t *testing.T) {
+	t.Parallel()
 	codemod := getExpiresIntegerToDayStringCodemod()
 
 	content := `---
@@ -282,6 +292,7 @@ safe-outputs:
 }
 
 func TestConvertExpiresLineToString_Integer(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name     string
 		input    string
@@ -334,6 +345,7 @@ func TestConvertExpiresLineToString_Integer(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			result, changed := convertExpiresIntegerLineToDayString(tt.input)
 			assert.Equal(t, tt.changed, changed, "changed flag should match")
 			assert.Equal(t, tt.expected, result, "converted line should match")
diff --git a/pkg/cli/codemod_factory_test.go b/pkg/cli/codemod_factory_test.go
index 00bff3c0710..49f691e9bc0 100644
--- a/pkg/cli/codemod_factory_test.go
+++ b/pkg/cli/codemod_factory_test.go
@@ -27,6 +27,7 @@ func baseFieldRemovalConfig() fieldRemovalCodemodConfig {
 }
 
 func TestNewFieldRemovalCodemod_Metadata(t *testing.T) {
+	t.Parallel()
 	cfg := baseFieldRemovalConfig()
 	codemod := newFieldRemovalCodemod(cfg)
 
@@ -38,6 +39,7 @@ func TestNewFieldRemovalCodemod_Metadata(t *testing.T) {
 }
 
 func TestNewFieldRemovalCodemod_ParentKeyMissing(t *testing.T) {
+	t.Parallel()
 	codemod := newFieldRemovalCodemod(baseFieldRemovalConfig())
 
 	content := `---
@@ -60,6 +62,7 @@ other: value
 }
 
 func TestNewFieldRemovalCodemod_ParentKeyWrongType(t *testing.T) {
+	t.Parallel()
 	codemod := newFieldRemovalCodemod(baseFieldRemovalConfig())
 
 	content := `---
@@ -82,6 +85,7 @@ parent: simple_string
 }
 
 func TestNewFieldRemovalCodemod_FieldKeyMissing(t *testing.T) {
+	t.Parallel()
 	codemod := newFieldRemovalCodemod(baseFieldRemovalConfig())
 
 	content := `---
@@ -107,6 +111,7 @@ parent:
 }
 
 func TestNewFieldRemovalCodemod_SuccessfulRemoval(t *testing.T) {
+	t.Parallel()
 	codemod := newFieldRemovalCodemod(baseFieldRemovalConfig())
 
 	content := `---
@@ -135,6 +140,7 @@ parent:
 }
 
 func TestNewFieldRemovalCodemod_PostTransformInvoked(t *testing.T) {
+	t.Parallel()
 	var postTransformCalled bool
 	var capturedFieldValue any
 
@@ -173,6 +179,7 @@ parent:
 }
 
 func TestNewFieldRemovalCodemod_PostTransformNotCalledWhenFieldAbsent(t *testing.T) {
+	t.Parallel()
 	var postTransformCalled bool
 
 	cfg := baseFieldRemovalConfig()
@@ -206,6 +213,7 @@ parent:
 }
 
 func TestNewFieldRemovalCodemod_TableDriven(t *testing.T) {
+	t.Parallel()
 	tests := []struct {
 		name        string
 		content     string
@@ -253,6 +261,7 @@ func TestNewFieldRemovalCodemod_TableDriven(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
 			codemod := newFieldRemovalCodemod(baseFieldRemovalConfig())
 
 			result, applied, err := codemod.Apply(tt.content, tt.frontmatter)
diff --git a/pkg/cli/codemod_github_app_client_id_test.go b/pkg/cli/codemod_github_app_client_id_test.go
index 9863800128b..125c50ee203 100644
--- a/pkg/cli/codemod_github_app_client_id_test.go
+++ b/pkg/cli/codemod_github_app_client_id_test.go
@@ -10,9 +10,11 @@ import (
 )
 
 func TestGitHubAppClientIDCodemod(t *testing.T) {
+	t.Parallel()
 	codemod := getGitHubAppClientIDCodemod()
 
 	t.Run("renames app-id under github-app blocks", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 github-app:
   app-id: ${{ vars.TOP_LEVEL_APP_ID }}
@@ -60,6 +62,7 @@ checkout:
 	})
 
 	t.Run("does not modify content without github-app.app-id", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 github-app:
   client-id: ${{ vars.APP_ID }}
@@ -80,6 +83,7 @@ github-app:
 	})
 
 	t.Run("does not rename app-id outside github-app blocks", func(t *testing.T) {
+		t.Parallel()
 		content := `---
 engine:
   provider: