fix(search): accept advertised repo filter formats in validation (ENT-1047)

ValidateRepoFilters rejected repo filter shapes the --repo help advertises
(gh/owner/repo, et/proj/repo, raw ULID) and that both the semantic v4 lookup
and the code-search resolver handle downstream, so `entire search --repo
gh/owner/repo` (or a ULID) failed early with an "invalid repo filter" error
even though it would resolve. Broaden isValidRepoFilter to accept owner/name
slugs, prefixed paths, and raw ULIDs while still rejecting junk like a bare
filename; unresolvable-but-well-formed filters now surface the meaningful
downstream "no matching repositories" message instead. Addresses the Copilot
review finding on PR #1845.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012QKSvbnbUJsnF1pvqqWb5u
Entire-Checkpoint: 01KY8GGERT9PYZ1K5YF9D1RX5V

Author: alishakawaguchi

cmd/entire/cli/search/search.go

@@ -12,6 +12,8 @@ import (
 	"strings"
 	"time"
 
+	ulid "github.com/oklog/ulid/v2"
+
 	"github.com/entireio/cli/cmd/entire/cli/api"
 )
 
@@ -497,23 +499,45 @@ func ValidateRepoFilters(repos []string) error {
 	for _, repo := range repos {
 		if !isValidRepoFilter(repo) {
 			return fmt.Errorf(
-				"invalid repo filter %q: expected owner/name or *; if you meant all repos, quote the asterisk: --repo '*'",
+				"invalid repo filter %q: expected owner/name, gh/owner/repo, a repo ULID, or *; if you meant all repos, quote the asterisk: --repo '*'",
 				repo,
 			)
 		}
 	}
 	return nil
 }
 
+// isValidRepoFilter reports whether repo is a filter shape the search backends
+// can resolve. It accepts every form the CLI help advertises and that the
+// resolvers handle downstream — a bare owner/name slug, a prefixed path
+// (gh/owner/repo, et/proj/repo, git/owner/repo), a raw repo ULID, or the
+// all-repos wildcard — so validation never rejects a filter the semantic v4
+// lookup (lookupFilter) or code-search resolver (resolveRepoFilters) would
+// otherwise resolve. It still rejects obvious mistakes like a bare filename.
 func isValidRepoFilter(repo string) bool {
 	if repo == AllReposFilter {
 		return true
 	}
-	if strings.Contains(repo, " ") {
+	if repo == "" || strings.Contains(repo, " ") {
 		return false
 	}
+	// Raw repo ULID: the v4 route keys on ULIDs and lookupFilter matches a
+	// prefix-less token against repo IDs.
+	if _, err := ulid.Parse(repo); err == nil {
+		return true
+	}
+	// A slug or prefixed path: owner/name or <prefix>/owner/repo. Every
+	// path segment must be non-empty.
 	parts := strings.Split(repo, "/")
-	return len(parts) == 2 && parts[0] != "" && parts[1] != ""
+	if len(parts) < 2 || len(parts) > 3 {
+		return false
+	}
+	for _, part := range parts {
+		if part == "" {
+			return false
+		}
+	}
+	return true
 }
 
 // AppendUnique appends values to existing, skipping any already present, and

cmd/entire/cli/search/search_test.go

@@ -599,12 +599,52 @@ func TestValidateRepoFilters_RejectsInvalidRepoValue(t *testing.T) {
 	if err == nil {
 		t.Fatal("expected validation error")
 	}
-	want := "invalid repo filter \"AGENTS.md\": expected owner/name or *; if you meant all repos, quote the asterisk: --repo '*'"
+	want := "invalid repo filter \"AGENTS.md\": expected owner/name, gh/owner/repo, a repo ULID, or *; if you meant all repos, quote the asterisk: --repo '*'"
 	if got := err.Error(); got != want {
 		t.Errorf("error = %q, want %q", got, want)
 	}
 }
 
+// The CLI --repo help advertises gh/owner/repo, et/proj/repo, and raw ULIDs,
+// and the semantic v4 lookup + code-search resolver both handle them. Validation
+// must accept the same set so it never rejects a filter that would resolve
+// downstream (ENT-1047 review finding).
+func TestValidateRepoFilters_AcceptsAdvertisedFormats(t *testing.T) {
+	t.Parallel()
+
+	valid := []string{
+		"entireio/cli",               // bare owner/name slug
+		"gh/entireio/cli",            // GitHub prefixed path
+		"et/proj/repo",               // Entire project prefixed path
+		"git/owner/repo",             // generic git prefixed path
+		"01ARZ3NDEKTSV4RRFFQ69G5FAV", // raw repo ULID (canonical)
+		"*",                          // all-repos wildcard
+	}
+	for _, repo := range valid {
+		if err := ValidateRepoFilters([]string{repo}); err != nil {
+			t.Errorf("ValidateRepoFilters(%q) = %v, want nil", repo, err)
+		}
+	}
+}
+
+func TestValidateRepoFilters_RejectsMalformed(t *testing.T) {
+	t.Parallel()
+
+	invalid := []string{
+		"AGENTS.md",  // bare filename, not a ULID or slug
+		"owner/",     // empty name segment
+		"/repo",      // empty owner segment
+		"a/b/c/d",    // too many path segments
+		"owner name", // contains a space
+		"gh//repo",   // empty middle segment in a prefixed path
+	}
+	for _, repo := range invalid {
+		if err := ValidateRepoFilters([]string{repo}); err == nil {
+			t.Errorf("ValidateRepoFilters(%q) = nil, want validation error", repo)
+		}
+	}
+}
+
 func TestParseSearchInput_QuotedAuthor(t *testing.T) {
 	t.Parallel()
 	p := ParseSearchInput(`author:"` + testAuthor + ` smith" fix bug`)