feat(trace): record the skills that an agent used in a session (#3551)

Author: jiparis

app/cli/internal/trace/claude/hooks.go

@@ -58,6 +58,10 @@ var commandTools = []string{"Bash"}
 // kind fired.
 var hookToolMatcher = strings.Join(append(append([]string{}, fileWritingTools...), commandTools...), "|")
 
+// postHookToolMatcher also covers the Skill tool. The skill is loaded only
+// after the call, so the post hook is the first one that can copy its folder.
+var postHookToolMatcher = hookToolMatcher + "|" + skillTool
+
 type hookEvent struct {
 	event   string
 	command string
@@ -68,7 +72,7 @@ var hookEvents = []hookEvent{
 	{eventSessionStart, "chainloop trace hook claude session-start", ""},
 	{eventUserPromptSubmit, "chainloop trace hook claude user-prompt-submit", ""},
 	{eventPreToolUse, "chainloop trace hook claude pre-tool-use", hookToolMatcher},
-	{eventPostToolUse, "chainloop trace hook claude post-tool-use", hookToolMatcher},
+	{eventPostToolUse, "chainloop trace hook claude post-tool-use", postHookToolMatcher},
 	{eventPostToolUseFailure, "chainloop trace hook claude post-tool-use", hookToolMatcher},
 	{eventSessionEnd, "chainloop trace hook claude session-end", ""},
 }

app/cli/internal/trace/claude/hooks_test.go

@@ -64,12 +64,13 @@ func TestInstallHooks(t *testing.T) {
 		preEntry := preEntries[0].(map[string]any)
 		assert.Equal(t, "Edit|Write|MultiEdit|Bash", preEntry["matcher"])
 
-		// PostToolUse should have matcher
+		// PostToolUse also matches Skill, to copy the folder of a loaded skill
 		postEntries := hooks["PostToolUse"].([]any)
 		postEntry := postEntries[0].(map[string]any)
-		assert.Equal(t, "Edit|Write|MultiEdit|Bash", postEntry["matcher"])
+		assert.Equal(t, "Edit|Write|MultiEdit|Bash|Skill", postEntry["matcher"])
 
-		// PostToolUseFailure should have the same matcher
+		// PostToolUseFailure keeps the edit matcher: a failed Skill call loads
+		// no skill
 		failureEntries := hooks["PostToolUseFailure"].([]any)
 		failureEntry := failureEntries[0].(map[string]any)
 		assert.Equal(t, "Edit|Write|MultiEdit|Bash", failureEntry["matcher"])