diff --git a/internal/beads/beads.go b/internal/beads/beads.go
index abfa161d..99da8da3 100644
--- a/internal/beads/beads.go
+++ b/internal/beads/beads.go
@@ -538,17 +538,27 @@ func (b *Beads) Update(id string, opts UpdateOptions) error {
 }
 
 // Close closes one or more issues.
+// If CLAUDE_SESSION_ID is set in the environment, it is passed to bd close
+// for work attribution tracking (see decision 009-session-events-architecture.md).
 func (b *Beads) Close(ids ...string) error {
 	if len(ids) == 0 {
 		return nil
 	}
 
 	args := append([]string{"close"}, ids...)
+
+	// Pass session ID for work attribution if available
+	if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+		args = append(args, "--session="+sessionID)
+	}
+
 	_, err := b.run(args...)
 	return err
 }
 
 // CloseWithReason closes one or more issues with a reason.
+// If CLAUDE_SESSION_ID is set in the environment, it is passed to bd close
+// for work attribution tracking (see decision 009-session-events-architecture.md).
 func (b *Beads) CloseWithReason(reason string, ids ...string) error {
 	if len(ids) == 0 {
 		return nil
@@ -556,6 +566,12 @@ func (b *Beads) CloseWithReason(reason string, ids ...string) error {
 
 	args := append([]string{"close"}, ids...)
 	args = append(args, "--reason="+reason)
+
+	// Pass session ID for work attribution if available
+	if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+		args = append(args, "--session="+sessionID)
+	}
+
 	_, err := b.run(args...)
 	return err
 }
diff --git a/internal/cmd/crew_lifecycle.go b/internal/cmd/crew_lifecycle.go
index 5b5aafb8..c2398970 100644
--- a/internal/cmd/crew_lifecycle.go
+++ b/internal/cmd/crew_lifecycle.go
@@ -90,7 +90,11 @@ func runCrewRemove(cmd *cobra.Command, args []string) error {
 		}
 		prefix := beads.GetPrefixForRig(townRoot, r.Name)
 		agentBeadID := beads.CrewBeadIDWithPrefix(prefix, r.Name, name)
-		closeCmd := exec.Command("bd", "close", agentBeadID, "--reason=Crew workspace removed")
+		closeArgs := []string{"close", agentBeadID, "--reason=Crew workspace removed"}
+		if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+			closeArgs = append(closeArgs, "--session="+sessionID)
+		}
+		closeCmd := exec.Command("bd", closeArgs...)
 		closeCmd.Dir = r.Path // Run from rig directory for proper beads resolution
 		if output, err := closeCmd.CombinedOutput(); err != nil {
 			// Non-fatal: bead might not exist or already be closed
diff --git a/internal/cmd/hook.go b/internal/cmd/hook.go
index b660892a..0f7862d0 100644
--- a/internal/cmd/hook.go
+++ b/internal/cmd/hook.go
@@ -143,8 +143,12 @@ func runHook(cmd *cobra.Command, args []string) error {
 			if !hookDryRun {
 				if hasAttachment {
 					// Close completed molecule bead (use bd close --force for pinned)
-					closeCmd := exec.Command("bd", "close", existing.ID, "--force",
-						"--reason=Auto-replaced by gt hook (molecule complete)")
+					closeArgs := []string{"close", existing.ID, "--force",
+						"--reason=Auto-replaced by gt hook (molecule complete)"}
+					if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+						closeArgs = append(closeArgs, "--session="+sessionID)
+					}
+					closeCmd := exec.Command("bd", closeArgs...)
 					closeCmd.Stderr = os.Stderr
 					if err := closeCmd.Run(); err != nil {
 						return fmt.Errorf("closing completed bead %s: %w", existing.ID, err)
diff --git a/internal/cmd/polecat.go b/internal/cmd/polecat.go
index dfbf76b2..57e7def9 100644
--- a/internal/cmd/polecat.go
+++ b/internal/cmd/polecat.go
@@ -1573,7 +1573,11 @@ func runPolecatNuke(cmd *cobra.Command, args []string) error {
 
 		// Step 5: Close agent bead (if exists)
 		agentBeadID := beads.PolecatBeadID(p.rigName, p.polecatName)
-		closeCmd := exec.Command("bd", "close", agentBeadID, "--reason=nuked")
+		closeArgs := []string{"close", agentBeadID, "--reason=nuked"}
+		if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+			closeArgs = append(closeArgs, "--session="+sessionID)
+		}
+		closeCmd := exec.Command("bd", closeArgs...)
 		closeCmd.Dir = filepath.Join(p.r.Path, "mayor", "rig")
 		if err := closeCmd.Run(); err != nil {
 			// Non-fatal - agent bead might not exist
diff --git a/internal/cmd/swarm.go b/internal/cmd/swarm.go
index df92fb50..b2c41cbe 100644
--- a/internal/cmd/swarm.go
+++ b/internal/cmd/swarm.go
@@ -816,7 +816,11 @@ func runSwarmLand(cmd *cobra.Command, args []string) error {
 	}
 
 	// Close the swarm epic in beads
-	closeCmd := exec.Command("bd", "close", swarmID, "--reason", "Swarm landed to main")
+	closeArgs := []string{"close", swarmID, "--reason", "Swarm landed to main"}
+	if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+		closeArgs = append(closeArgs, "--session="+sessionID)
+	}
+	closeCmd := exec.Command("bd", closeArgs...)
 	closeCmd.Dir = foundRig.BeadsPath()
 	if err := closeCmd.Run(); err != nil {
 		style.PrintWarning("couldn't close swarm epic in beads: %v", err)
@@ -871,7 +875,11 @@ func runSwarmCancel(cmd *cobra.Command, args []string) error {
 	}
 
 	// Close the swarm epic in beads with cancelled reason
-	closeCmd := exec.Command("bd", "close", swarmID, "--reason", "Swarm cancelled")
+	closeArgs := []string{"close", swarmID, "--reason", "Swarm cancelled"}
+	if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+		closeArgs = append(closeArgs, "--session="+sessionID)
+	}
+	closeCmd := exec.Command("bd", closeArgs...)
 	closeCmd.Dir = foundRig.BeadsPath()
 	if err := closeCmd.Run(); err != nil {
 		return fmt.Errorf("closing swarm: %w", err)
diff --git a/internal/cmd/synthesis.go b/internal/cmd/synthesis.go
index 655a0624..a5d3f5e4 100644
--- a/internal/cmd/synthesis.go
+++ b/internal/cmd/synthesis.go
@@ -321,7 +321,11 @@ func runSynthesisClose(cmd *cobra.Command, args []string) error {
 	}
 
 	// Close the convoy
-	closeCmd := exec.Command("bd", "close", convoyID, "--reason=synthesis complete")
+	closeArgs := []string{"close", convoyID, "--reason=synthesis complete"}
+	if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+		closeArgs = append(closeArgs, "--session="+sessionID)
+	}
+	closeCmd := exec.Command("bd", closeArgs...)
 	closeCmd.Dir = townBeads
 	closeCmd.Stderr = os.Stderr
 
diff --git a/internal/mail/mailbox.go b/internal/mail/mailbox.go
index e68fdb11..e4fc0108 100644
--- a/internal/mail/mailbox.go
+++ b/internal/mail/mailbox.go
@@ -313,7 +313,12 @@ func (m *Mailbox) markReadBeads(id string) error {
 
 // closeInDir closes a message in a specific beads directory.
 func (m *Mailbox) closeInDir(id, beadsDir string) error {
-	cmd := exec.Command("bd", "close", id)
+	args := []string{"close", id}
+	// Pass session ID for work attribution if available
+	if sessionID := os.Getenv("CLAUDE_SESSION_ID"); sessionID != "" {
+		args = append(args, "--session="+sessionID)
+	}
+	cmd := exec.Command("bd", args...)
 	cmd.Dir = m.workDir
 	cmd.Env = append(cmd.Environ(), "BEADS_DIR="+beadsDir)