diff --git a/internal/storage/sqlite/dependencies.go b/internal/storage/sqlite/dependencies.go
index 1e9bfcbe..24bce118 100644
--- a/internal/storage/sqlite/dependencies.go
+++ b/internal/storage/sqlite/dependencies.go
@@ -221,8 +221,13 @@ func (s *SQLiteStorage) RemoveDependency(ctx context.Context, issueID, dependsOn
 			return fmt.Errorf("failed to record event: %w", err)
 		}
 
-		// Mark both issues as dirty for incremental export
-		if err := markIssuesDirtyTx(ctx, tx, []string{issueID, dependsOnID}); err != nil {
+		// Mark issues as dirty for incremental export
+		// For external refs, only mark the source issue (target doesn't exist locally)
+		issueIDsToMark := []string{issueID}
+		if !strings.HasPrefix(dependsOnID, "external:") {
+			issueIDsToMark = append(issueIDsToMark, dependsOnID)
+		}
+		if err := markIssuesDirtyTx(ctx, tx, issueIDsToMark); err != nil {
 			return wrapDBError("mark issues dirty after removing dependency", err)
 		}
 
diff --git a/internal/storage/sqlite/dependencies_test.go b/internal/storage/sqlite/dependencies_test.go
index c643ae2c..185c6207 100644
--- a/internal/storage/sqlite/dependencies_test.go
+++ b/internal/storage/sqlite/dependencies_test.go
@@ -1610,3 +1610,50 @@ func TestDetectCycles_RelatesTypeAllowsBidirectionalWithoutCycleReport(t *testin
 		t.Error("Expected B to relate-to A")
 	}
 }
+
+// TestRemoveDependencyExternal verifies that removing an external dependency
+// doesn't cause FK violation (bd-a3sj). External refs like external:project:capability
+// don't exist in the issues table, so we must not mark them as dirty.
+func TestRemoveDependencyExternal(t *testing.T) {
+	store, cleanup := setupTestDB(t)
+	defer cleanup()
+
+	ctx := context.Background()
+
+	// Create an issue
+	issue := &types.Issue{
+		Title:     "Issue with external dep",
+		Status:    types.StatusOpen,
+		Priority:  1,
+		IssueType: types.TypeTask,
+	}
+	if err := store.CreateIssue(ctx, issue, "test-user"); err != nil {
+		t.Fatalf("CreateIssue failed: %v", err)
+	}
+
+	// Add an external dependency
+	externalRef := "external:other-project:some-capability"
+	dep := &types.Dependency{
+		IssueID:     issue.ID,
+		DependsOnID: externalRef,
+		Type:        types.DepBlocks,
+	}
+	if err := store.AddDependency(ctx, dep, "test-user"); err != nil {
+		t.Fatalf("AddDependency failed: %v", err)
+	}
+
+	// This should NOT cause FK violation (the bug was marking external ref as dirty)
+	err := store.RemoveDependency(ctx, issue.ID, externalRef, "test-user")
+	if err != nil {
+		t.Fatalf("RemoveDependency on external ref should succeed, got: %v", err)
+	}
+
+	// Verify dependency was actually removed
+	deps, err := store.GetDependencyRecords(ctx, issue.ID)
+	if err != nil {
+		t.Fatalf("GetDependencyRecords failed: %v", err)
+	}
+	if len(deps) != 0 {
+		t.Errorf("Expected 0 dependencies after removal, got %d", len(deps))
+	}
+}
diff --git a/internal/types/types.go b/internal/types/types.go
index d005e73c..3fc6f9d1 100644
--- a/internal/types/types.go
+++ b/internal/types/types.go
@@ -4,6 +4,7 @@ package types
 import (
 	"crypto/sha256"
 	"fmt"
+	"strings"
 	"time"
 )
 
@@ -54,6 +55,10 @@ type Issue struct {
 
 	// Bonding fields (bd-rnnr): compound molecule lineage
 	BondedFrom []BondRef `json:"bonded_from,omitempty"` // For compounds: constituent protos
+
+	// HOP fields (bd-7pwh): entity tracking for CV chains
+	Creator     *EntityRef   `json:"creator,omitempty"`     // Who created this issue (human, agent, or org)
+	Validations []Validation `json:"validations,omitempty"` // Who validated/approved this work
 }
 
 // ComputeContentHash creates a deterministic hash of the issue's content.
@@ -103,6 +108,38 @@ func (i *Issue) ComputeContentHash() string {
 		h.Write([]byte(br.BondPoint))
 		h.Write([]byte{0})
 	}
+	// Hash creator for HOP entity tracking (bd-m7ib)
+	if i.Creator != nil {
+		h.Write([]byte(i.Creator.Name))
+		h.Write([]byte{0})
+		h.Write([]byte(i.Creator.Platform))
+		h.Write([]byte{0})
+		h.Write([]byte(i.Creator.Org))
+		h.Write([]byte{0})
+		h.Write([]byte(i.Creator.ID))
+		h.Write([]byte{0})
+	}
+	// Hash validations for HOP proof-of-stake (bd-du9h)
+	for _, v := range i.Validations {
+		if v.Validator != nil {
+			h.Write([]byte(v.Validator.Name))
+			h.Write([]byte{0})
+			h.Write([]byte(v.Validator.Platform))
+			h.Write([]byte{0})
+			h.Write([]byte(v.Validator.Org))
+			h.Write([]byte{0})
+			h.Write([]byte(v.Validator.ID))
+			h.Write([]byte{0})
+		}
+		h.Write([]byte(v.Outcome))
+		h.Write([]byte{0})
+		h.Write([]byte(v.Timestamp.Format(time.RFC3339)))
+		h.Write([]byte{0})
+		if v.Score != nil {
+			h.Write([]byte(fmt.Sprintf("%f", *v.Score)))
+		}
+		h.Write([]byte{0})
+	}
 
 	return fmt.Sprintf("%x", h.Sum(nil))
 }
@@ -577,3 +614,118 @@ func (i *Issue) IsCompound() bool {
 func (i *Issue) GetConstituents() []BondRef {
 	return i.BondedFrom
 }
+
+// EntityRef is a structured reference to an entity (human, agent, or org).
+// This is the foundation for HOP entity tracking and CV chains.
+// Can be rendered as a URI: entity://hop/<platform>/<org>/<id>
+//
+// Example usage:
+//
+//	ref := &EntityRef{
+//	    Name:     "polecat/Nux",
+//	    Platform: "gastown",
+//	    Org:      "steveyegge",
+//	    ID:       "polecat-nux",
+//	}
+//	uri := ref.URI() // "entity://hop/gastown/steveyegge/polecat-nux"
+type EntityRef struct {
+	// Name is the human-readable identifier (e.g., "polecat/Nux", "mayor")
+	Name string `json:"name,omitempty"`
+
+	// Platform identifies the execution context (e.g., "gastown", "github")
+	Platform string `json:"platform,omitempty"`
+
+	// Org identifies the organization (e.g., "steveyegge", "anthropics")
+	Org string `json:"org,omitempty"`
+
+	// ID is the unique identifier within the platform/org (e.g., "polecat-nux")
+	ID string `json:"id,omitempty"`
+}
+
+// IsEmpty returns true if all fields are empty.
+func (e *EntityRef) IsEmpty() bool {
+	if e == nil {
+		return true
+	}
+	return e.Name == "" && e.Platform == "" && e.Org == "" && e.ID == ""
+}
+
+// URI returns the entity as a HOP URI.
+// Format: entity://hop/<platform>/<org>/<id>
+// Returns empty string if Platform, Org, or ID is missing.
+func (e *EntityRef) URI() string {
+	if e == nil || e.Platform == "" || e.Org == "" || e.ID == "" {
+		return ""
+	}
+	return fmt.Sprintf("entity://hop/%s/%s/%s", e.Platform, e.Org, e.ID)
+}
+
+// String returns a human-readable representation.
+// Prefers Name if set, otherwise returns URI or ID.
+func (e *EntityRef) String() string {
+	if e == nil {
+		return ""
+	}
+	if e.Name != "" {
+		return e.Name
+	}
+	if uri := e.URI(); uri != "" {
+		return uri
+	}
+	return e.ID
+}
+
+// Validation records who validated/approved work completion.
+// This is core to HOP's proof-of-stake concept - validators stake
+// their reputation on approvals.
+type Validation struct {
+	// Validator is who approved/rejected the work
+	Validator *EntityRef `json:"validator"`
+
+	// Outcome is the validation result: accepted, rejected, revision_requested
+	Outcome string `json:"outcome"`
+
+	// Timestamp is when the validation occurred
+	Timestamp time.Time `json:"timestamp"`
+
+	// Score is an optional quality score (0.0-1.0)
+	Score *float32 `json:"score,omitempty"`
+}
+
+// Validation outcome constants
+const (
+	ValidationAccepted          = "accepted"
+	ValidationRejected          = "rejected"
+	ValidationRevisionRequested = "revision_requested"
+)
+
+// IsValidOutcome checks if the outcome is a known validation outcome.
+func (v *Validation) IsValidOutcome() bool {
+	switch v.Outcome {
+	case ValidationAccepted, ValidationRejected, ValidationRevisionRequested:
+		return true
+	}
+	return false
+}
+
+// ParseEntityURI parses a HOP entity URI into an EntityRef.
+// Format: entity://hop/<platform>/<org>/<id>
+// Returns nil and error if the URI is invalid.
+func ParseEntityURI(uri string) (*EntityRef, error) {
+	const prefix = "entity://hop/"
+	if !strings.HasPrefix(uri, prefix) {
+		return nil, fmt.Errorf("invalid entity URI: must start with %q", prefix)
+	}
+
+	rest := uri[len(prefix):]
+	parts := strings.SplitN(rest, "/", 3)
+	if len(parts) != 3 || parts[0] == "" || parts[1] == "" || parts[2] == "" {
+		return nil, fmt.Errorf("invalid entity URI: expected entity://hop/<platform>/<org>/<id>, got %q", uri)
+	}
+
+	return &EntityRef{
+		Platform: parts[0],
+		Org:      parts[1],
+		ID:       parts[2],
+	}, nil
+}
diff --git a/internal/types/types_test.go b/internal/types/types_test.go
index 0b93e77f..08dff97d 100644
--- a/internal/types/types_test.go
+++ b/internal/types/types_test.go
@@ -959,3 +959,311 @@ func TestSetDefaults(t *testing.T) {
 		})
 	}
 }
+
+// EntityRef tests (bd-nmch: HOP entity tracking foundation)
+
+func TestEntityRefIsEmpty(t *testing.T) {
+	tests := []struct {
+		name   string
+		ref    *EntityRef
+		expect bool
+	}{
+		{"nil ref", nil, true},
+		{"empty ref", &EntityRef{}, true},
+		{"only name", &EntityRef{Name: "test"}, false},
+		{"only platform", &EntityRef{Platform: "gastown"}, false},
+		{"only org", &EntityRef{Org: "steveyegge"}, false},
+		{"only id", &EntityRef{ID: "polecat-nux"}, false},
+		{"full ref", &EntityRef{Name: "polecat/Nux", Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"}, false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.ref.IsEmpty(); got != tt.expect {
+				t.Errorf("EntityRef.IsEmpty() = %v, want %v", got, tt.expect)
+			}
+		})
+	}
+}
+
+func TestEntityRefURI(t *testing.T) {
+	tests := []struct {
+		name   string
+		ref    *EntityRef
+		expect string
+	}{
+		{"nil ref", nil, ""},
+		{"empty ref", &EntityRef{}, ""},
+		{"missing platform", &EntityRef{Org: "steveyegge", ID: "polecat-nux"}, ""},
+		{"missing org", &EntityRef{Platform: "gastown", ID: "polecat-nux"}, ""},
+		{"missing id", &EntityRef{Platform: "gastown", Org: "steveyegge"}, ""},
+		{"full ref", &EntityRef{Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"}, "entity://hop/gastown/steveyegge/polecat-nux"},
+		{"with name", &EntityRef{Name: "polecat/Nux", Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"}, "entity://hop/gastown/steveyegge/polecat-nux"},
+		{"github platform", &EntityRef{Platform: "github", Org: "anthropics", ID: "claude-code"}, "entity://hop/github/anthropics/claude-code"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.ref.URI(); got != tt.expect {
+				t.Errorf("EntityRef.URI() = %q, want %q", got, tt.expect)
+			}
+		})
+	}
+}
+
+func TestEntityRefString(t *testing.T) {
+	tests := []struct {
+		name   string
+		ref    *EntityRef
+		expect string
+	}{
+		{"nil ref", nil, ""},
+		{"empty ref", &EntityRef{}, ""},
+		{"only name", &EntityRef{Name: "polecat/Nux"}, "polecat/Nux"},
+		{"full ref with name", &EntityRef{Name: "polecat/Nux", Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"}, "polecat/Nux"},
+		{"full ref without name", &EntityRef{Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"}, "entity://hop/gastown/steveyegge/polecat-nux"},
+		{"only id", &EntityRef{ID: "polecat-nux"}, "polecat-nux"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.ref.String(); got != tt.expect {
+				t.Errorf("EntityRef.String() = %q, want %q", got, tt.expect)
+			}
+		})
+	}
+}
+
+func TestParseEntityURI(t *testing.T) {
+	tests := []struct {
+		name      string
+		uri       string
+		expect    *EntityRef
+		expectErr bool
+	}{
+		{
+			name:   "valid URI",
+			uri:    "entity://hop/gastown/steveyegge/polecat-nux",
+			expect: &EntityRef{Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"},
+		},
+		{
+			name:   "github URI",
+			uri:    "entity://hop/github/anthropics/claude-code",
+			expect: &EntityRef{Platform: "github", Org: "anthropics", ID: "claude-code"},
+		},
+		{
+			name:   "id with slashes",
+			uri:    "entity://hop/gastown/steveyegge/polecat/nux",
+			expect: &EntityRef{Platform: "gastown", Org: "steveyegge", ID: "polecat/nux"},
+		},
+		{
+			name:      "wrong prefix",
+			uri:       "beads://hop/gastown/steveyegge/polecat-nux",
+			expectErr: true,
+		},
+		{
+			name:      "missing hop",
+			uri:       "entity://gastown/steveyegge/polecat-nux",
+			expectErr: true,
+		},
+		{
+			name:      "too few parts",
+			uri:       "entity://hop/gastown/steveyegge",
+			expectErr: true,
+		},
+		{
+			name:      "empty platform",
+			uri:       "entity://hop//steveyegge/polecat-nux",
+			expectErr: true,
+		},
+		{
+			name:      "empty org",
+			uri:       "entity://hop/gastown//polecat-nux",
+			expectErr: true,
+		},
+		{
+			name:      "empty id",
+			uri:       "entity://hop/gastown/steveyegge/",
+			expectErr: true,
+		},
+		{
+			name:      "empty string",
+			uri:       "",
+			expectErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := ParseEntityURI(tt.uri)
+			if tt.expectErr {
+				if err == nil {
+					t.Errorf("ParseEntityURI(%q) expected error, got nil", tt.uri)
+				}
+				return
+			}
+			if err != nil {
+				t.Errorf("ParseEntityURI(%q) unexpected error: %v", tt.uri, err)
+				return
+			}
+			if got.Platform != tt.expect.Platform || got.Org != tt.expect.Org || got.ID != tt.expect.ID {
+				t.Errorf("ParseEntityURI(%q) = %+v, want %+v", tt.uri, got, tt.expect)
+			}
+		})
+	}
+}
+
+func TestEntityRefRoundTrip(t *testing.T) {
+	// Test that URI() and ParseEntityURI() are inverses
+	original := &EntityRef{Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"}
+	uri := original.URI()
+	parsed, err := ParseEntityURI(uri)
+	if err != nil {
+		t.Fatalf("ParseEntityURI(%q) error: %v", uri, err)
+	}
+	if parsed.Platform != original.Platform || parsed.Org != original.Org || parsed.ID != original.ID {
+		t.Errorf("Round trip failed: got %+v, want %+v", parsed, original)
+	}
+}
+
+func TestComputeContentHashWithCreator(t *testing.T) {
+	// Test that Creator field affects the content hash (bd-m7ib)
+	issue1 := Issue{
+		Title:     "Test Issue",
+		Status:    StatusOpen,
+		Priority:  2,
+		IssueType: TypeTask,
+	}
+
+	issue2 := Issue{
+		Title:     "Test Issue",
+		Status:    StatusOpen,
+		Priority:  2,
+		IssueType: TypeTask,
+		Creator:   &EntityRef{Name: "polecat/Nux", Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"},
+	}
+
+	hash1 := issue1.ComputeContentHash()
+	hash2 := issue2.ComputeContentHash()
+
+	if hash1 == hash2 {
+		t.Error("Expected different hash when Creator is set")
+	}
+
+	// Same creator should produce same hash
+	issue3 := Issue{
+		Title:     "Test Issue",
+		Status:    StatusOpen,
+		Priority:  2,
+		IssueType: TypeTask,
+		Creator:   &EntityRef{Name: "polecat/Nux", Platform: "gastown", Org: "steveyegge", ID: "polecat-nux"},
+	}
+
+	hash3 := issue3.ComputeContentHash()
+	if hash2 != hash3 {
+		t.Error("Expected same hash for identical Creator")
+	}
+}
+
+// Validation tests (bd-du9h: HOP proof-of-stake)
+
+func TestValidationIsValidOutcome(t *testing.T) {
+	tests := []struct {
+		outcome string
+		valid   bool
+	}{
+		{ValidationAccepted, true},
+		{ValidationRejected, true},
+		{ValidationRevisionRequested, true},
+		{"unknown", false},
+		{"", false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.outcome, func(t *testing.T) {
+			v := &Validation{Outcome: tt.outcome}
+			if got := v.IsValidOutcome(); got != tt.valid {
+				t.Errorf("Validation{Outcome: %q}.IsValidOutcome() = %v, want %v", tt.outcome, got, tt.valid)
+			}
+		})
+	}
+}
+
+func TestComputeContentHashWithValidations(t *testing.T) {
+	// Test that Validations field affects the content hash (bd-du9h)
+	ts := time.Date(2025, 12, 22, 10, 30, 0, 0, time.UTC)
+
+	issue1 := Issue{
+		Title:     "Test Issue",
+		Status:    StatusClosed,
+		Priority:  2,
+		IssueType: TypeTask,
+		ClosedAt:  &ts,
+	}
+
+	issue2 := Issue{
+		Title:     "Test Issue",
+		Status:    StatusClosed,
+		Priority:  2,
+		IssueType: TypeTask,
+		ClosedAt:  &ts,
+		Validations: []Validation{
+			{
+				Validator: &EntityRef{Platform: "gastown", Org: "steveyegge", ID: "refinery"},
+				Outcome:   ValidationAccepted,
+				Timestamp: ts,
+			},
+		},
+	}
+
+	hash1 := issue1.ComputeContentHash()
+	hash2 := issue2.ComputeContentHash()
+
+	if hash1 == hash2 {
+		t.Error("Expected different hash when Validations is set")
+	}
+
+	// Same validations should produce same hash
+	issue3 := Issue{
+		Title:     "Test Issue",
+		Status:    StatusClosed,
+		Priority:  2,
+		IssueType: TypeTask,
+		ClosedAt:  &ts,
+		Validations: []Validation{
+			{
+				Validator: &EntityRef{Platform: "gastown", Org: "steveyegge", ID: "refinery"},
+				Outcome:   ValidationAccepted,
+				Timestamp: ts,
+			},
+		},
+	}
+
+	hash3 := issue3.ComputeContentHash()
+	if hash2 != hash3 {
+		t.Error("Expected same hash for identical Validations")
+	}
+
+	// Test with score
+	score := float32(0.95)
+	issue4 := Issue{
+		Title:     "Test Issue",
+		Status:    StatusClosed,
+		Priority:  2,
+		IssueType: TypeTask,
+		ClosedAt:  &ts,
+		Validations: []Validation{
+			{
+				Validator: &EntityRef{Platform: "gastown", Org: "steveyegge", ID: "refinery"},
+				Outcome:   ValidationAccepted,
+				Timestamp: ts,
+				Score:     &score,
+			},
+		},
+	}
+
+	hash4 := issue4.ComputeContentHash()
+	if hash2 == hash4 {
+		t.Error("Expected different hash when Score is added")
+	}
+}