feat: include rotated agent logs in support bundles (#26055)

Support bundles previously captured only the active coder-agent.log, losing
history across agent restarts. Add an optional `after` filter to the agent's
/debug/logs endpoint: without it the endpoint is unchanged (active log only,
10 MiB cap); with it the response includes the active log plus rotated
coder-agent-*.log files modified after the cutoff, newest first. Support
bundles request the last 24h.

Closes #25395

codersdk/workspacesdk/agentconn.go

@@ -98,7 +98,7 @@ type AgentConn interface {
 	CallMCPTool(ctx context.Context, req CallMCPToolRequest) (CallMCPToolResponse, error)
 	Close() error
 	ContextConfig(ctx context.Context) (ContextConfigResponse, error)
-	DebugLogs(ctx context.Context) ([]byte, error)
+	DebugLogs(ctx context.Context, opts ...DebugLogsOption) ([]byte, error)
 	DebugMagicsock(ctx context.Context) ([]byte, error)
 	DebugManifest(ctx context.Context) ([]byte, error)
 	DialContext(ctx context.Context, network string, addr string) (net.Conn, error)
@@ -443,11 +443,29 @@ func (c *agentConn) DebugManifest(ctx context.Context) ([]byte, error) {
 	return bs, nil
 }
 
-// DebugLogs returns up to the last 10MB of `/tmp/coder-agent.log`
-func (c *agentConn) DebugLogs(ctx context.Context) ([]byte, error) {
+// DebugLogsOption configures a DebugLogs request.
+type DebugLogsOption func(*debugLogsConfig)
+
+type debugLogsConfig struct {
+	after time.Time
+}
+
+// WithLogsAfter also returns rotated logs modified at or after t, separated by
+// boundary markers (100 MiB combined cap).
+func WithLogsAfter(t time.Time) DebugLogsOption {
+	return func(c *debugLogsConfig) { c.after = t }
+}
+
+// DebugLogs returns up to 10 MiB of the active agent log. Pass WithLogsAfter to
+// also include rotated logs.
+func (c *agentConn) DebugLogs(ctx context.Context, opts ...DebugLogsOption) ([]byte, error) {
+	var cfg debugLogsConfig
+	for _, opt := range opts {
+		opt(&cfg)
+	}
 	ctx, span := tracing.StartSpan(ctx)
 	defer span.End()
-	res, err := c.apiRequest(ctx, http.MethodGet, "/debug/logs", nil)
+	res, err := c.apiRequest(ctx, http.MethodGet, debugLogsPath(cfg.after), nil)
 	if err != nil {
 		return nil, xerrors.Errorf("do request: %w", err)
 	}
@@ -462,6 +480,14 @@ func (c *agentConn) DebugLogs(ctx context.Context) ([]byte, error) {
 	return bs, nil
 }
 
+func debugLogsPath(after time.Time) string {
+	query := neturl.Values{}
+	if !after.IsZero() {
+		query.Set("after", after.UTC().Format(time.RFC3339Nano))
+	}
+	return agentAPIPath("/debug/logs", query)
+}
+
 // PrometheusMetrics returns a response from the agent's prometheus metrics endpoint
 func (c *agentConn) PrometheusMetrics(ctx context.Context) ([]byte, error) {
 	ctx, span := tracing.StartSpan(ctx)

codersdk/workspacesdk/agentconn_internal_test.go

@@ -3,6 +3,7 @@ package workspacesdk
 import (
 	neturl "net/url"
 	"testing"
+	"time"
 
 	"github.com/stretchr/testify/require"
 )
@@ -48,4 +49,22 @@ func TestAgentAPIPath(t *testing.T) {
 		require.Equal(t, "50", parsed.Query().Get("max_response_lines"))
 		require.Equal(t, "60", parsed.Query().Get("max_response_bytes"))
 	})
+
+	t.Run("debug logs zero after", func(t *testing.T) {
+		t.Parallel()
+
+		got := debugLogsPath(time.Time{})
+		require.Equal(t, "/debug/logs", got)
+	})
+
+	t.Run("debug logs after", func(t *testing.T) {
+		t.Parallel()
+
+		after := time.Date(2026, 5, 18, 12, 34, 56, 789, time.FixedZone("test", -7*60*60))
+		got := debugLogsPath(after)
+		parsed, err := neturl.Parse(got)
+		require.NoError(t, err)
+		require.Equal(t, "/debug/logs", parsed.Path)
+		require.Equal(t, after.UTC().Format(time.RFC3339Nano), parsed.Query().Get("after"))
+	})
 }

codersdk/workspacesdk/agentconnmock/agentconnmock.go

@@ -130,18 +130,23 @@ func (mr *MockAgentConnMockRecorder) ContextConfig(ctx any) *gomock.Call {
 }
 
 // DebugLogs mocks base method.
-func (m *MockAgentConn) DebugLogs(ctx context.Context) ([]byte, error) {
+func (m *MockAgentConn) DebugLogs(ctx context.Context, opts ...workspacesdk.DebugLogsOption) ([]byte, error) {
 	m.ctrl.T.Helper()
-	ret := m.ctrl.Call(m, "DebugLogs", ctx)
+	varargs := []any{ctx}
+	for _, a := range opts {
+		varargs = append(varargs, a)
+	}
+	ret := m.ctrl.Call(m, "DebugLogs", varargs...)
 	ret0, _ := ret[0].([]byte)
 	ret1, _ := ret[1].(error)
 	return ret0, ret1
 }
 
 // DebugLogs indicates an expected call of DebugLogs.
-func (mr *MockAgentConnMockRecorder) DebugLogs(ctx any) *gomock.Call {
+func (mr *MockAgentConnMockRecorder) DebugLogs(ctx any, opts ...any) *gomock.Call {
 	mr.mock.ctrl.T.Helper()
-	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "DebugLogs", reflect.TypeOf((*MockAgentConn)(nil).DebugLogs), ctx)
+	varargs := append([]any{ctx}, opts...)
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "DebugLogs", reflect.TypeOf((*MockAgentConn)(nil).DebugLogs), varargs...)
 }
 
 // DebugMagicsock mocks base method.