fix(validation): support hyphenated prefixes in ValidateIDFormat (#1013)

* test(validation): add failing tests for hyphenated prefix parsing

Reproduces bug where `bd create --parent` fails for projects with
hyphenated prefixes like "bead-me-up" or "web-app".

Root cause: ValidateIDFormat splits on first hyphen, so:
  "bead-me-up-3e9.1" → prefix "bead" (wrong, should be "bead-me-up")

The bug flow in create.go:
1. User runs: bd create "Child" --parent bead-me-up-3e9
2. GetNextChildID generates: bead-me-up-3e9.1
3. ValidateIDFormat extracts: "bead" (splits at first hyphen)
4. ValidatePrefix compares: "bead" vs "bead-me-up" → MISMATCH

Tests added:
- TestValidateIDFormat: 6 cases for hyphenated prefix IDs
- TestValidateIDFormat_ParentChildFlow: simulates exact --parent flow,
  showing simple prefixes pass while hyphenated prefixes fail

Workaround: use --force flag to bypass prefix validation.

* fix(validation): support hyphenated prefixes in ValidateIDFormat

Use utils.ExtractIssuePrefix instead of naive first-hyphen splitting.
This fixes bd create --parent failing for projects with hyphenated
prefixes like "bead-me-up" or "web-app".

Before: "bead-me-up-3e9" → prefix "bead" (wrong)
After:  "bead-me-up-3e9" → prefix "bead-me-up" (correct)

ExtractIssuePrefix uses smart heuristics: split on last hyphen,
check if suffix is hash-like (3-8 chars, alphanumeric, digits for 4+).

* Update internal/validation/bead_test.go

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

internal/validation/bead.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"github.com/steveyegge/beads/internal/types"
+	"github.com/steveyegge/beads/internal/utils"
 )
 
 // ParsePriority extracts and validates a priority value from content.
@@ -51,6 +52,7 @@ func ValidatePriority(priorityStr string) (int, error) {
 
 // ValidateIDFormat validates that an ID has the correct format.
 // Supports: prefix-number (bd-42), prefix-hash (bd-a3f8e9), or hierarchical (bd-a3f8e9.1)
+// Also supports hyphenated prefixes like "bead-me-up-3e9" or "web-app-abc123".
 // Returns the prefix part or an error if invalid.
 func ValidateIDFormat(id string) (string, error) {
 	if id == "" {
@@ -62,9 +64,11 @@ func ValidateIDFormat(id string) (string, error) {
 		return "", fmt.Errorf("invalid ID format '%s' (expected format: prefix-hash or prefix-hash.number, e.g., 'bd-a3f8e9' or 'bd-a3f8e9.1')", id)
 	}
 
-	// Extract prefix (before the first hyphen)
-	hyphenIdx := strings.Index(id, "-")
-	prefix := id[:hyphenIdx]
+	// Use ExtractIssuePrefix which correctly handles hyphenated prefixes
+	// by looking at the last hyphen and checking if suffix is hash-like.
+	// This fixes the bug where "bead-me-up-3e9" was parsed as prefix "bead"
+	// instead of "bead-me-up".
+	prefix := utils.ExtractIssuePrefix(id)
 
 	return prefix, nil
 }

internal/validation/bead_test.go

@@ -93,6 +93,16 @@ func TestValidateIDFormat(t *testing.T) {
 		{"bd-a3f8e9.1", "bd", false},
 		{"foo-bar", "foo", false},
 		{"nohyphen", "", true},
+
+		// Hyphenated prefix support
+		// These test cases verify that ValidateIDFormat correctly extracts
+		// prefixes containing hyphens (e.g., "bead-me-up" not just "bead")
+		{"bead-me-up-3e9", "bead-me-up", false},           // 3-char hash suffix
+		{"bead-me-up-3e9.1", "bead-me-up", false},         // hierarchical child
+		{"bead-me-up-3e9.1.2", "bead-me-up", false},       // deeply nested child
+		{"web-app-a3f8e9", "web-app", false},              // 6-char hash suffix
+		{"my-cool-project-1a2b", "my-cool-project", false}, // 4-char hash suffix
+		{"document-intelligence-0sa", "document-intelligence", false}, // 3-char hash
 	}
 
 	for _, tt := range tests {
@@ -109,6 +119,90 @@ func TestValidateIDFormat(t *testing.T) {
 	}
 }
 
+// TestValidateIDFormat_ParentChildFlow tests the exact scenario that fails with --parent flag:
+// When creating a child of a parent with a hyphenated prefix, the generated child ID
+// (e.g., "bead-me-up-3e9.1") should have its prefix correctly extracted as "bead-me-up",
+// not "bead". This test simulates the create.go flow at lines 352-391.
+func TestValidateIDFormat_ParentChildFlow(t *testing.T) {
+	tests := []struct {
+		name         string
+		parentID     string
+		childSuffix  string
+		dbPrefix     string
+		wantPrefix   string
+		shouldMatch  bool
+	}{
+		{
+			name:        "simple prefix - child creation works",
+			parentID:    "bd-a3f8e9",
+			childSuffix: ".1",
+			dbPrefix:    "bd",
+			wantPrefix:  "bd",
+			shouldMatch: true,
+		},
+		{
+			name:        "hyphenated prefix - child creation FAILS with current impl",
+			parentID:    "bead-me-up-3e9",
+			childSuffix: ".1",
+			dbPrefix:    "bead-me-up",
+			wantPrefix:  "bead-me-up", // Current impl returns "bead" - THIS IS THE BUG
+			shouldMatch: true,
+		},
+		{
+			name:        "hyphenated prefix - deeply nested child",
+			parentID:    "bead-me-up-3e9.1",
+			childSuffix: ".2",
+			dbPrefix:    "bead-me-up",
+			wantPrefix:  "bead-me-up",
+			shouldMatch: true,
+		},
+		{
+			name:        "multi-hyphen prefix - web-app style",
+			parentID:    "web-app-abc123",
+			childSuffix: ".1",
+			dbPrefix:    "web-app",
+			wantPrefix:  "web-app",
+			shouldMatch: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// Simulate the child ID generation that happens in create.go:352
+			childID := tt.parentID + tt.childSuffix
+
+			// Simulate the validation flow from create.go:361
+			extractedPrefix, err := ValidateIDFormat(childID)
+			if err != nil {
+				t.Fatalf("ValidateIDFormat(%q) unexpected error: %v", childID, err)
+			}
+
+			// Check that extracted prefix matches expected
+			if extractedPrefix != tt.wantPrefix {
+				t.Errorf("ValidateIDFormat(%q) extracted prefix = %q, want %q",
+					childID, extractedPrefix, tt.wantPrefix)
+			}
+
+			// Simulate the prefix validation from create.go:389
+			// This is where the "prefix mismatch" error occurs
+			err = ValidatePrefix(extractedPrefix, tt.dbPrefix, false)
+			prefixMatches := (err == nil)
+
+			if prefixMatches != tt.shouldMatch {
+				if tt.shouldMatch {
+					t.Errorf("--parent %s flow: prefix validation failed unexpectedly: %v\n"+
+						"  Child ID: %s\n"+
+						"  Extracted prefix: %q\n"+
+						"  Database prefix: %q",
+						tt.parentID, err, childID, extractedPrefix, tt.dbPrefix)
+				} else {
+					t.Errorf("--parent %s flow: expected prefix mismatch but validation passed", tt.parentID)
+				}
+			}
+		})
+	}
+}
+
 func TestParseIssueType(t *testing.T) {
 	tests := []struct {
 		name         string