loop: auto-infer TaskState from actual tool results each round

pkg/agent/loop.go

@@ -451,6 +451,12 @@ func run(ctx context.Context, cfg agentConfig, state state) error {
 			cfg.SaveSession()
 		}
 
+		// Auto-update TaskState from what actually happened this round.
+		if ts := state.taskState(); ts != nil {
+			inferTaskStateUpdate(ts, msg, results)
+			state.updateTaskState(*ts)
+		}
+
 		if interrupted {
 			return ctx.Err()
 		}
@@ -540,6 +546,45 @@ func contextBudget(ctx context.Context, b backend.Backend) int {
 	return ctxLen / 2
 }
 
+// inferTaskStateUpdate updates TaskState fields from the actual tool round
+// without requiring model cooperation. Keeps the state current even if the
+// model ignores re-injection nudges.
+func inferTaskStateUpdate(ts *TaskState, msg backend.Message, results []toolResult) {
+	// LastAction: summarize what tools ran and whether they succeeded.
+	if len(msg.ToolCalls) > 0 {
+		names := make([]string, 0, len(msg.ToolCalls))
+		for _, tc := range msg.ToolCalls {
+			names = append(names, tc.Name)
+		}
+		errCount := 0
+		for _, r := range results {
+			if r.IsError {
+				errCount++
+			}
+		}
+		action := strings.Join(names, ", ")
+		if errCount > 0 {
+			action += fmt.Sprintf(" (%d/%d failed)", errCount, len(results))
+		}
+		ts.LastAction = action
+	}
+
+	// PlanStep: extract from PLAN: block if present in assistant text.
+	if idx := strings.Index(msg.Content, "PLAN:"); idx >= 0 {
+		lines := strings.Split(msg.Content[idx:], "\n")
+		for _, line := range lines[1:] {
+			trimmed := strings.TrimSpace(line)
+			if strings.HasPrefix(trimmed, "- [ ]") {
+				ts.PlanStep = strings.TrimSpace(trimmed[5:])
+				break
+			}
+			if trimmed == "" || (!strings.HasPrefix(trimmed, "- [") && trimmed != "") {
+				break
+			}
+		}
+	}
+}
+
 // hasTextToolCall returns true when the assistant text contains a registered
 // tool name immediately followed by ':' or '(', indicating the model tried to
 // invoke a tool by writing the call as plain text rather than via the API.