v1.21.1

Fixed

• guard now fails closed on a degraded review without --sarif. When the review degraded (an unparsable model response, live, replayed from cache, or a --from-json document carrying meta.degrade_reason), guard exits 1 with a “policy cannot be verified” error instead of reading the empty result as zero findings and passing. The --sarif path already refused a degraded review. review and diff --fail-on keep their graceful-degrade behavior. See Policy gate.
• gemini-cli rejects an oversized prompt before starting gemini. The prompt travels as a command-line argument, so a large diff used to fail with an opaque E2BIG-shaped error. It now returns a localized message with the prompt size and the limit, and suggests narrowing with --file/--dir (or --exclude-file/--exclude-dir). An argument list too long error from the OS is mapped to the same message for every CLI-backed provider.
• leaks no longer reports a missing git binary as an invalid guard.secret_patterns entry; it shows the localized “git not found” / “not a repository” message.
• The early Error: prefix follows the same language order as every other message (--lang, repo config, user config, English) instead of --lang only.
• leaks --json sets meta.truncated: true when --max-commits cut the history short (additive; meta.walk_truncated is unchanged). See Leaks.
• --text branch-name matching is bounded by the commit walk ceiling instead of --max-commits, so a cut is reported as truncation rather than dropped silently.

Changed

• Building from source now requires Go 1.26 or later (go install, make build). Prebuilt binaries (Homebrew, Scoop, GitHub Releases) are unaffected.
• Dependency updates: anthropic-sdk-go, genai, go-git, and the golang.org/x modules. The Anthropic SDK links the OpenTelemetry API; CommitBrief configures no tracer or exporter, so it stays a no-op and sends nothing.