From 43eccfaee2c9dbe5757f50e0d47ae14e38454723 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Carlos=20Flor=C3=AAncio?= <carlosmflorencio@gmail.com>
Date: Tue, 3 Mar 2026 19:54:12 +0000
Subject: [PATCH] feat: improve closing resources (PTYs, connections) (#355)

---
 .../agent/lifecycle/manager_interaction.go         | 14 ++++++++------
 apps/backend/internal/agentctl/client/client.go    |  3 ++-
 .../internal/agentctl/server/process/manager.go    |  3 +++
 .../internal/agentctl/server/process/runner.go     |  3 +++
 .../internal/agentctl/server/shell/session.go      |  8 ++++++++
 5 files changed, 24 insertions(+), 7 deletions(-)

diff --git a/apps/backend/internal/agent/lifecycle/manager_interaction.go b/apps/backend/internal/agent/lifecycle/manager_interaction.go
index fae80b04d1..23818a8fdf 100644
--- a/apps/backend/internal/agent/lifecycle/manager_interaction.go
+++ b/apps/backend/internal/agent/lifecycle/manager_interaction.go
@@ -90,12 +90,14 @@ func (m *Manager) StopAgentWithReason(ctx context.Context, executionID string, r
 		zap.Bool("force", force),
 		zap.String("runtime", execution.RuntimeName))
 
-	// Try to gracefully stop via agentctl first
-	if execution.agentctl != nil && !force {
-		if err := execution.agentctl.Stop(ctx); err != nil {
-			m.logger.Warn("failed to stop agent via agentctl",
-				zap.String("execution_id", executionID),
-				zap.Error(err))
+	// Try to gracefully stop via agentctl first, then always close connections
+	if execution.agentctl != nil {
+		if !force {
+			if err := execution.agentctl.Stop(ctx); err != nil {
+				m.logger.Warn("failed to stop agent via agentctl",
+					zap.String("execution_id", executionID),
+					zap.Error(err))
+			}
 		}
 		execution.agentctl.Close()
 	}
diff --git a/apps/backend/internal/agentctl/client/client.go b/apps/backend/internal/agentctl/client/client.go
index 2e7a4eabc9..a8cc12aabf 100644
--- a/apps/backend/internal/agentctl/client/client.go
+++ b/apps/backend/internal/agentctl/client/client.go
@@ -532,10 +532,11 @@ type (
 	ProcessStatusUpdate    = types.ProcessStatusUpdate
 )
 
-// Close closes all connections
+// Close closes all connections and releases resources
 func (c *Client) Close() {
 	c.CloseUpdatesStream()
 	c.CloseWorkspaceStream()
+	c.httpClient.CloseIdleConnections()
 }
 
 // readResponseBody reads and returns the response body
diff --git a/apps/backend/internal/agentctl/server/process/manager.go b/apps/backend/internal/agentctl/server/process/manager.go
index 85e999e02c..2e1a54380b 100644
--- a/apps/backend/internal/agentctl/server/process/manager.go
+++ b/apps/backend/internal/agentctl/server/process/manager.go
@@ -412,10 +412,13 @@ func (m *Manager) startProcessPipes() error {
 	}
 	m.stdout, err = m.cmd.StdoutPipe()
 	if err != nil {
+		_ = m.stdin.Close()
 		return fmt.Errorf("failed to create stdout pipe: %w", err)
 	}
 	m.stderr, err = m.cmd.StderrPipe()
 	if err != nil {
+		_ = m.stdin.Close()
+		_ = m.stdout.Close()
 		return fmt.Errorf("failed to create stderr pipe: %w", err)
 	}
 	return nil
diff --git a/apps/backend/internal/agentctl/server/process/runner.go b/apps/backend/internal/agentctl/server/process/runner.go
index 1a758453dc..a9b83afa7f 100644
--- a/apps/backend/internal/agentctl/server/process/runner.go
+++ b/apps/backend/internal/agentctl/server/process/runner.go
@@ -245,6 +245,7 @@ func (r *ProcessRunner) Start(ctx context.Context, req StartProcessRequest) (*Pr
 	}
 	stderr, err := cmd.StderrPipe()
 	if err != nil {
+		_ = stdout.Close()
 		return nil, fmt.Errorf("failed to attach stderr: %w", err)
 	}
 
@@ -296,6 +297,8 @@ func (r *ProcessRunner) Start(ctx context.Context, req StartProcessRequest) (*Pr
 // On failure, marks the process as failed and removes it from tracking.
 func (r *ProcessRunner) startAndActivate(proc *commandProcess, cmd *exec.Cmd, id string, stdout, stderr io.ReadCloser) error {
 	if err := cmd.Start(); err != nil {
+		_ = stdout.Close()
+		_ = stderr.Close()
 		proc.mu.Lock()
 		proc.info.Status = types.ProcessStatusFailed
 		proc.info.UpdatedAt = time.Now().UTC()
diff --git a/apps/backend/internal/agentctl/server/shell/session.go b/apps/backend/internal/agentctl/server/shell/session.go
index 6520b42fe9..bc5684b361 100644
--- a/apps/backend/internal/agentctl/server/shell/session.go
+++ b/apps/backend/internal/agentctl/server/shell/session.go
@@ -379,6 +379,14 @@ func (s *Session) respawn() error {
 		return nil
 	}
 
+	// Close old PTY to prevent file descriptor leak.
+	// Don't nil out s.pty — readOutput() may still be reading from it
+	// concurrently without the mutex. Closing is sufficient: any in-flight
+	// Read() will return an error and the goroutine will exit.
+	if s.pty != nil {
+		_ = s.pty.Close()
+	}
+
 	s.cmd = exec.Command(s.shell, s.shellArgs...)
 	s.cmd.Dir = s.workDir
 	s.cmd.Env = buildShellEnv(s.workDir)