fix(agent): address code review feedback

- Replace deprecated strings.Title with manual capitalize
- Fix race: set codexClient.onMessage before starting reader goroutine
- Remove unused msgCh parameter from codexClient.handleLine
- Route agent stderr through logger instead of dumping to os.Stderr
- Use deterministic agent order in ensurePaired (prefer codex)
- Increase message channel buffer from 64 to 256
- Rename test to match function rename (buildPrompt)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/cmd/daemon/daemon.go

@@ -263,7 +263,7 @@ func (d *daemon) registerRuntimes(ctx context.Context) ([]daemonRuntime, error)
 			continue
 		}
 		runtimes = append(runtimes, map[string]string{
-			"name":    fmt.Sprintf("Local %s", strings.Title(name)),
+			"name":    fmt.Sprintf("Local %s", strings.ToUpper(name[:1])+name[1:]),
 			"type":    name,
 			"version": version,
 			"status":  "online",
@@ -293,13 +293,15 @@ func (d *daemon) registerRuntimes(ctx context.Context) ([]daemonRuntime, error)
 }
 
 func (d *daemon) ensurePaired(ctx context.Context) (string, error) {
-	// Use the first available agent for the pairing session metadata.
+	// Use a deterministic agent for the pairing session metadata (prefer codex for backward compat).
 	var firstName string
 	var firstEntry agentEntry
-	for name, entry := range d.cfg.Agents {
-		firstName = name
-		firstEntry = entry
-		break
+	for _, preferred := range []string{"codex", "claude"} {
+		if entry, ok := d.cfg.Agents[preferred]; ok {
+			firstName = preferred
+			firstEntry = entry
+			break
+		}
 	}
 	version, err := agent.DetectVersion(ctx, firstEntry.Path)
 	if err != nil {

server/cmd/daemon/daemon_test.go

@@ -37,7 +37,7 @@ func TestResolveTaskWorkdirUsesRepoPathWhenPresent(t *testing.T) {
 	}
 }
 
-func TestBuildCodexPromptIncludesIssueAndSkills(t *testing.T) {
+func TestBuildPromptIncludesIssueAndSkills(t *testing.T) {
 	t.Parallel()
 
 	prompt := buildPrompt(daemonTask{

server/pkg/agent/claude.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
+	"log"
 	"os"
 	"os/exec"
 	"strings"
@@ -64,7 +65,7 @@ func (b *claudeBackend) Execute(ctx context.Context, prompt string, opts ExecOpt
 		cancel()
 		return nil, fmt.Errorf("claude stdin pipe: %w", err)
 	}
-	cmd.Stderr = os.Stderr
+	cmd.Stderr = newLogWriter(b.cfg.Logger, "[claude:stderr] ")
 
 	if err := cmd.Start(); err != nil {
 		cancel()
@@ -73,7 +74,7 @@ func (b *claudeBackend) Execute(ctx context.Context, prompt string, opts ExecOpt
 
 	b.cfg.Logger.Printf("[claude] started pid=%d cwd=%s model=%s", cmd.Process.Pid, opts.Cwd, opts.Model)
 
-	msgCh := make(chan Message, 64)
+	msgCh := make(chan Message, 256)
 	resCh := make(chan Result, 1)
 
 	go func() {
@@ -303,6 +304,8 @@ func trySend(ch chan<- Message, msg Message) {
 	select {
 	case ch <- msg:
 	default:
+		// Channel full — drop message. Final output is accumulated separately
+		// in Result.Output, so only streaming consumers are affected.
 	}
 }
 
@@ -322,3 +325,21 @@ func detectCLIVersion(ctx context.Context, execPath string) (string, error) {
 	}
 	return strings.TrimSpace(string(data)), nil
 }
+
+// logWriter adapts a *log.Logger to an io.Writer for capturing stderr.
+type logWriter struct {
+	logger *log.Logger
+	prefix string
+}
+
+func newLogWriter(logger *log.Logger, prefix string) *logWriter {
+	return &logWriter{logger: logger, prefix: prefix}
+}
+
+func (w *logWriter) Write(p []byte) (int, error) {
+	text := strings.TrimSpace(string(p))
+	if text != "" {
+		w.logger.Printf("%s%s", w.prefix, text)
+	}
+	return len(p), nil
+}

server/pkg/agent/codex.go

@@ -5,7 +5,6 @@ import (
 	"context"
 	"encoding/json"
 	"fmt"
-	"os"
 	"os/exec"
 	"strings"
 	"sync"
@@ -49,7 +48,7 @@ func (b *codexBackend) Execute(ctx context.Context, prompt string, opts ExecOpti
 		cancel()
 		return nil, fmt.Errorf("codex stdin pipe: %w", err)
 	}
-	cmd.Stderr = os.Stderr
+	cmd.Stderr = newLogWriter(b.cfg.Logger, "[codex:stderr] ")
 
 	if err := cmd.Start(); err != nil {
 		cancel()
@@ -58,15 +57,24 @@ func (b *codexBackend) Execute(ctx context.Context, prompt string, opts ExecOpti
 
 	b.cfg.Logger.Printf("[codex] started app-server pid=%d cwd=%s", cmd.Process.Pid, opts.Cwd)
 
+	msgCh := make(chan Message, 256)
+	resCh := make(chan Result, 1)
+
+	var output strings.Builder
+
 	c := &codexClient{
 		cfg:     b.cfg,
 		stdin:   stdin,
 		pending: make(map[int]*pendingRPC),
+		// Set onMessage before starting the reader goroutine to avoid a race.
+		onMessage: func(msg Message) {
+			if msg.Type == MessageText {
+				output.WriteString(msg.Content)
+			}
+			trySend(msgCh, msg)
+		},
 	}
 
-	msgCh := make(chan Message, 64)
-	resCh := make(chan Result, 1)
-
 	// Start reading stdout in background
 	go func() {
 		scanner := bufio.NewScanner(stdout)
@@ -76,7 +84,7 @@ func (b *codexBackend) Execute(ctx context.Context, prompt string, opts ExecOpti
 			if line == "" {
 				continue
 			}
-			c.handleLine(line, msgCh)
+			c.handleLine(line)
 		}
 		c.closeAllPending(fmt.Errorf("codex process exited"))
 	}()
@@ -94,15 +102,6 @@ func (b *codexBackend) Execute(ctx context.Context, prompt string, opts ExecOpti
 		startTime := time.Now()
 		finalStatus := "completed"
 		var finalError string
-		var output strings.Builder
-
-		// Drain messages to accumulate output
-		c.onMessage = func(msg Message) {
-			if msg.Type == MessageText {
-				output.WriteString(msg.Content)
-			}
-			trySend(msgCh, msg)
-		}
 
 		// 1. Initialize handshake
 		_, err := c.request(runCtx, "initialize", map[string]any{
@@ -308,7 +307,7 @@ func (c *codexClient) closeAllPending(err error) {
 	}
 }
 
-func (c *codexClient) handleLine(line string, msgCh chan<- Message) {
+func (c *codexClient) handleLine(line string) {
 	var raw map[string]json.RawMessage
 	if err := json.Unmarshal([]byte(line), &raw); err != nil {
 		return