diff --git a/CLAUDE.md b/CLAUDE.md
index 726a23f..8c8063a 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -94,7 +94,7 @@ Optional daemon services (feature-gated via config):
 - **CCInfoTimerService**: Lazy-fetch background timer for Claude Code statusline data (cost, quota, git info), plus an always-on Anthropic usage sync (10-min interval, only while a `claude` process is running) that pushes quota to `/api/v1/anthropic-usage` without needing statusline activity
 - **CodexUsageSyncService**: Syncs Codex usage to `/api/v1/codex-usage` every 10 min, only while a `codex`/`chatgpt` process is running (both intervals share the `usageSyncInterval` const in `daemon/usage_sync.go`)
 - **SyncCircuitBreakerService**: Retry failed syncs with file-based persistence (`sync_pending.log`) and hourly recovery timer
-- **AICodeOtelServer**: gRPC OTEL collector for AI coding CLI metrics/logs (Claude Code, Codex)
+- **AICodeOtelServer**: gRPC OTEL collector for AI coding CLI metrics/logs (Claude Code, Codex). In a Claude Code cloud session (`CLAUDE_CODE_REMOTE=true`, where the SessionStart hook starts the daemon) it adds the VM's `CLAUDE_CODE_REMOTE_SESSION_ID` as the `ccr.session.id` attribute to Claude Code records that lack it; the server marks those sessions as cloud sessions. `daemon/main_test.go` clears both variables so tests behave the same inside a cloud session
 - **HeartbeatResyncService**: Periodic resync of failed heartbeats (30-min interval)
 - **CleanupTimerService**: Periodic log file cleanup (24-hour interval)
 
diff --git a/daemon/aicode_otel_processor.go b/daemon/aicode_otel_processor.go
index a28ae66..56fab13 100644
--- a/daemon/aicode_otel_processor.go
+++ b/daemon/aicode_otel_processor.go
@@ -35,6 +35,9 @@ type AICodeOtelProcessor struct {
 	endpoint model.Endpoint
 	hostname string
 	debug    bool
+	// cloudSessionID is the Claude Code cloud session the daemon runs in (from its environment),
+	// added to Claude Code records that don't carry one. Empty on a local machine.
+	cloudSessionID string
 
 	// maxRequestBytes bounds the JSON body of one backend request; larger batches are split.
 	maxRequestBytes int
@@ -59,10 +62,24 @@ func NewAICodeOtelProcessor(config model.ShellTimeConfig) *AICodeOtelProcessor {
 		},
 		hostname:        hostname,
 		debug:           debug,
+		cloudSessionID:  model.CloudSessionIDFromEnv(os.Getenv),
 		maxRequestBytes: model.AICodeOtelMaxRequestBytes,
 	}
 }
 
+// fillCloudSessionID adds the daemon's cloud session id to the attributes of a Claude Code
+// record that doesn't carry ccr.session.id yet. In a cloud VM the daemon is started by the
+// session's SessionStart hook, so every Claude Code record it receives belongs to that session.
+func (p *AICodeOtelProcessor) fillCloudSessionID(attrs map[string]any, source string) map[string]any {
+	if p.cloudSessionID == "" || source != model.AICodeOtelSourceClaudeCode {
+		return attrs
+	}
+	if _, ok := attrs[model.AICodeCloudSessionIDAttribute]; ok {
+		return attrs
+	}
+	return setAttribute(attrs, model.AICodeCloudSessionIDAttribute, p.cloudSessionID)
+}
+
 // writeDebugFile appends JSON-formatted data to a debug file
 func (p *AICodeOtelProcessor) writeDebugFile(filename string, data interface{}) {
 	debugDir := filepath.Join(os.TempDir(), "shelltime")
@@ -474,6 +491,9 @@ func (p *AICodeOtelProcessor) parseMetric(m *metricsv1.Metric, res *otelResource
 		}
 		// Apply resource attributes first
 		applyResourceAttributesToMetric(&metric, res.attrs)
+		// Seeded before the data point's attributes, so they can't crowd it out; a ccr.session.id
+		// on the data point still wins.
+		metric.Attributes = p.fillCloudSessionID(metric.Attributes, res.source)
 		// Then extract data point attributes (can override resource attrs)
 		for _, attr := range dp.GetAttributes() {
 			applyMetricAttribute(&metric, attr, metricType)
@@ -562,6 +582,8 @@ func (p *AICodeOtelProcessor) parseLogRecord(lr *logsv1.LogRecord, res *otelReso
 	for _, key := range keys {
 		event.Attributes = setAttribute(event.Attributes, key, res.attrs.Attributes[key])
 	}
+	// Seeded the same way: a ccr.session.id on the record itself still wins.
+	event.Attributes = p.fillCloudSessionID(event.Attributes, res.source)
 
 	var fallbacks eventFallbacks
 	for _, attr := range lr.GetAttributes() {
diff --git a/daemon/aicode_otel_processor_v2_test.go b/daemon/aicode_otel_processor_v2_test.go
index 3c0f2f3..1134a2f 100644
--- a/daemon/aicode_otel_processor_v2_test.go
+++ b/daemon/aicode_otel_processor_v2_test.go
@@ -842,6 +842,55 @@ func TestParseMetric_TypeRoutingAndAttributes(t *testing.T) {
 	assert.Equal(t, "Write", legacyTool.Tool)
 }
 
+// In a cloud VM the daemon adds its session's ccr.session.id to Claude Code records that lack
+// it; a value Claude Code sent wins, and Codex records are left alone.
+func TestCloudSessionIDFallback(t *testing.T) {
+	t.Setenv("CLAUDE_CODE_REMOTE", "true")
+	t.Setenv("CLAUDE_CODE_REMOTE_SESSION_ID", "cse_01Daemon")
+	p := NewAICodeOtelProcessor(model.ShellTimeConfig{})
+	require.Equal(t, "cse_01Daemon", p.cloudSessionID)
+
+	claude := newOtelResource(claudeTestResource(), model.AICodeOtelSourceClaudeCode)
+	event := p.parseLogRecord(claudeRecord("user_prompt", kv("prompt", strVal("hi"))), claude, "test-scope")
+	require.NotNil(t, event)
+	assert.Equal(t, "cse_01Daemon", event.Attributes[model.AICodeCloudSessionIDAttribute])
+
+	event = p.parseLogRecord(claudeRecord("user_prompt", kv("ccr.session.id", strVal("cse_01Claude"))), claude, "test-scope")
+	require.NotNil(t, event)
+	assert.Equal(t, "cse_01Claude", event.Attributes[model.AICodeCloudSessionIDAttribute], "Claude Code's own value wins")
+
+	delta := metricsv1.AggregationTemporality_AGGREGATION_TEMPORALITY_DELTA
+	metrics := p.parseMetric(sumMetric("claude_code.active_time.total", delta, 30, kv("type", strVal("cli"))), claude, "com.anthropic.claude_code")
+	require.Len(t, metrics, 1)
+	assert.Equal(t, "cse_01Daemon", metrics[0].Attributes[model.AICodeCloudSessionIDAttribute])
+
+	metrics = p.parseMetric(sumMetric("claude_code.active_time.total", delta, 30, kv("ccr.session.id", strVal("cse_01Claude"))), claude, "com.anthropic.claude_code")
+	require.Len(t, metrics, 1)
+	assert.Equal(t, "cse_01Claude", metrics[0].Attributes[model.AICodeCloudSessionIDAttribute])
+
+	// Seeded before the data point's attributes, so a data point at the attribute cap can't crowd
+	// it out.
+	full := make([]*commonv1.KeyValue, 0, model.AICodeOtelMaxAttributes)
+	for i := range model.AICodeOtelMaxAttributes {
+		full = append(full, kv(fmt.Sprintf("attr.%d", i), strVal("v")))
+	}
+	metrics = p.parseMetric(sumMetric("claude_code.active_time.total", delta, 30, full...), claude, "com.anthropic.claude_code")
+	require.Len(t, metrics, 1)
+	assert.Equal(t, "cse_01Daemon", metrics[0].Attributes[model.AICodeCloudSessionIDAttribute])
+
+	codex := newOtelResource(codexTestResource(), model.AICodeOtelSourceCodex)
+	event = p.parseLogRecord(codexRecord("user_prompt", kv("prompt", strVal("hi"))), codex, "test-scope")
+	require.NotNil(t, event)
+	assert.NotContains(t, event.Attributes, model.AICodeCloudSessionIDAttribute, "Codex isn't a Claude Code cloud session")
+
+	// On a local machine nothing is added.
+	local := NewAICodeOtelProcessor(model.ShellTimeConfig{})
+	local.cloudSessionID = ""
+	event = local.parseLogRecord(claudeRecord("user_prompt", kv("prompt", strVal("hi"))), claude, "test-scope")
+	require.NotNil(t, event)
+	assert.NotContains(t, event.Attributes, model.AICodeCloudSessionIDAttribute)
+}
+
 func TestParseMetric_CumulativeTemporalityWarnsOnce(t *testing.T) {
 	var buf bytes.Buffer
 	var mu sync.Mutex
diff --git a/daemon/main_test.go b/daemon/main_test.go
new file mode 100644
index 0000000..7fc9848
--- /dev/null
+++ b/daemon/main_test.go
@@ -0,0 +1,14 @@
+package daemon
+
+import (
+	"os"
+	"testing"
+)
+
+// TestMain clears the Claude Code cloud session environment, so the suite gives the same results
+// inside a cloud session (where CLAUDE_CODE_REMOTE=true) as on CI.
+func TestMain(m *testing.M) {
+	os.Unsetenv("CLAUDE_CODE_REMOTE")
+	os.Unsetenv("CLAUDE_CODE_REMOTE_SESSION_ID")
+	os.Exit(m.Run())
+}
diff --git a/model/aicode_cloud_session.go b/model/aicode_cloud_session.go
new file mode 100644
index 0000000..81f70eb
--- /dev/null
+++ b/model/aicode_cloud_session.go
@@ -0,0 +1,19 @@
+package model
+
+import "strings"
+
+// AICodeCloudSessionIDAttribute is the standard attribute Claude Code puts on every event and
+// metric of a cloud session (claude.ai/code): its CLAUDE_CODE_REMOTE_SESSION_ID, like cse_01AbC.
+// The server marks sessions that carry it as cloud sessions.
+const AICodeCloudSessionIDAttribute = "ccr.session.id"
+
+// CloudSessionIDFromEnv returns the Claude Code cloud session the process runs in, or "". A
+// cloud VM sets CLAUDE_CODE_REMOTE=true (never true on a local machine) and
+// CLAUDE_CODE_REMOTE_SESSION_ID; the daemon inherits both from the SessionStart hook that
+// starts it there.
+func CloudSessionIDFromEnv(getenv func(string) string) string {
+	if getenv("CLAUDE_CODE_REMOTE") != "true" {
+		return ""
+	}
+	return strings.TrimSpace(getenv("CLAUDE_CODE_REMOTE_SESSION_ID"))
+}
diff --git a/model/aicode_cloud_session_test.go b/model/aicode_cloud_session_test.go
new file mode 100644
index 0000000..2691a7b
--- /dev/null
+++ b/model/aicode_cloud_session_test.go
@@ -0,0 +1,27 @@
+package model
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestCloudSessionIDFromEnv(t *testing.T) {
+	tests := []struct {
+		name string
+		env  map[string]string
+		want string
+	}{
+		{name: "local machine", env: map[string]string{"TERM_PROGRAM": "ghostty"}, want: ""},
+		{name: "cloud session", env: map[string]string{"CLAUDE_CODE_REMOTE": "true", "CLAUDE_CODE_REMOTE_SESSION_ID": " cse_01AbC\n"}, want: "cse_01AbC"},
+		{name: "remote flag off", env: map[string]string{"CLAUDE_CODE_REMOTE": "false", "CLAUDE_CODE_REMOTE_SESSION_ID": "cse_01AbC"}, want: ""},
+		{name: "id without the flag", env: map[string]string{"CLAUDE_CODE_REMOTE_SESSION_ID": "cse_01AbC"}, want: ""},
+		{name: "flag without an id", env: map[string]string{"CLAUDE_CODE_REMOTE": "true"}, want: ""},
+		{name: "blank id", env: map[string]string{"CLAUDE_CODE_REMOTE": "true", "CLAUDE_CODE_REMOTE_SESSION_ID": "   "}, want: ""},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			require.Equal(t, tt.want, CloudSessionIDFromEnv(func(k string) string { return tt.env[k] }))
+		})
+	}
+}