Fix __GH_AW_WIKI_NOTE__ placeholder not substituted when wiki is disabled

pkg/workflow/repo_memory_prompt.go

@@ -10,6 +10,11 @@ import (
 
 var repoMemoryPromptLog = logger.New("workflow:repo_memory_prompt")
 
+// ghaEmptyStringExpr is the GitHub Actions expression that evaluates to an empty string.
+// Using this as an env var value forces the prompt-creation step to include the variable,
+// ensuring the substitution step always has a value to substitute.
+const ghaEmptyStringExpr = "${{ '' }}"
+
 // buildRepoMemoryPromptSection builds a PromptSection for repo memory instructions.
 // Returns a PromptSection that references a template file with substitutions, or nil if no memory is configured.
 func buildRepoMemoryPromptSection(config *RepoMemoryConfig) *PromptSection {
@@ -58,8 +63,13 @@ func buildRepoMemoryPromptSection(config *RepoMemoryConfig) *PromptSection {
 			constraintsText = constraints.String()
 		}
 
-		// Build wiki note text (non-empty only when wiki mode is enabled)
-		wikiNoteText := ""
+		// Build wiki note text.
+		// When wiki mode is enabled, include a note about the GitHub Wiki.
+		// When wiki mode is disabled, use a GitHub expression that evaluates to the empty string
+		// (${{ '' }}). This ensures that, in newly compiled workflows (or workflows with regenerated
+		// lock files), expression interpolation always substitutes __GH_AW_WIKI_NOTE__ with a value
+		// by forcing the prompt-creation step to include GH_AW_WIKI_NOTE, even when the note is empty.
+		wikiNoteText := ghaEmptyStringExpr
 		if memory.Wiki {
 			repoMemoryPromptLog.Print("Wiki mode enabled for repo memory")
 			wikiNoteText = "\n\n> **GitHub Wiki**: This memory is backed by the GitHub Wiki for this repository. " +

pkg/workflow/repo_memory_test.go

@@ -1118,7 +1118,7 @@ func TestRepoMemoryWikiPromptSection(t *testing.T) {
 	assert.Contains(t, wikiNote, "Markdown", "Wiki note should mention Markdown syntax")
 }
 
-// TestRepoMemoryNonWikiPromptSection tests that non-wiki mode has empty wiki note
+// TestRepoMemoryNonWikiPromptSection tests that non-wiki mode uses empty string expression for wiki note
 func TestRepoMemoryNonWikiPromptSection(t *testing.T) {
 	config := &RepoMemoryConfig{
 		Memories: []RepoMemoryEntry{
@@ -1135,7 +1135,9 @@ func TestRepoMemoryNonWikiPromptSection(t *testing.T) {
 	require.NotNil(t, section.EnvVars, "Expected env vars")
 
 	wikiNote := section.EnvVars["GH_AW_WIKI_NOTE"]
-	assert.Empty(t, wikiNote, "Non-wiki mode should have empty GH_AW_WIKI_NOTE")
+	// Non-wiki mode should use a GitHub expression that evaluates to empty string.
+	// This ensures __GH_AW_WIKI_NOTE__ is always substituted via expression interpolation.
+	assert.Equal(t, ghaEmptyStringExpr, wikiNote, "Non-wiki mode should use empty string expression for GH_AW_WIKI_NOTE")
 }
 
 // TestRepoMemoryWikiPushAllowedRepos tests that wiki mode sets REPO_MEMORY_ALLOWED_REPOS