feat(desktop): add Gemini CLI as a tier-2 preset harness

Gemini CLI ships native ACP support (gemini --acp) with no adapter
needed, but had no PresetHarness entry. Adds the preset (command,
args, install hint/URL), an inline SVG mark, and settings copy.

Splits the tier-2 preset block (struct, PRESET_HARNESSES, and its two
accessor fns) out of discovery.rs into a new sibling module
discovery/presets.rs — discovery.rs was already past the desktop
file-size ratchet, so a bare addition to PRESET_HARNESSES would have
failed just desktop-check. No behavior change from the split itself.

Signed-off-by: JPeetz <88510961+JPeetz@users.noreply.github.com>

Author: JPeetz

desktop/public/harness-logos/CREDITS.md

@@ -25,6 +25,7 @@ Monochrome marks inlined as `currentColor` paths in
 |---|---|---|---|---|---|
 | Goose | [block/goose](https://github.com/block/goose) | `305849b71709b95b86ed9f11bd3bc939899c0aab` | Apache-2.0 © Block, Inc. | `documentation/static/img/goose.svg` | `fill="#101010"` → `currentColor`; dropped the redundant clipPath wrapper |
 | Cursor | [simple-icons](https://github.com/simple-icons/simple-icons) | `16.27.1` (slug `cursor`) | CC0-1.0 (path data); nominative use of the Cursor mark to identify Cursor's harness | `icons/cursor.svg` | `fill` → `currentColor` |
+| Gemini | [simple-icons](https://github.com/simple-icons/simple-icons) | `16.27.1` (slug `googlegemini`) | CC0-1.0 (path data); nominative use of the Gemini mark to identify Gemini CLI's harness | `icons/googlegemini.svg` | `fill` → `currentColor` |
 
 Codex deliberately has **no** bundled mark: the OpenAI blossom was removed
 from simple-icons in v16 at the vendor's request, so we do not ship it —

desktop/src-tauri/src/managed_agents/discovery.rs

@@ -1436,224 +1436,13 @@ pub(crate) fn discover_acp_runtime_availability(runtime_id: &str) -> Option<AcpA
         .map(|partial| partial.entry.availability)
 }
 
-// ── Tier-2 preset harnesses ────────────────────────────────────────────────
-//
-// Static data for well-known ACP harnesses that have bundled logos and
-// verified command/args. PATH-probed at discovery time (Detected badge);
-// not editable or deletable by users. Logos are bundled assets referenced
-// by id in the frontend `RUNTIME_LOGOS` map.
-
-struct PresetHarness {
-    id: &'static str,
-    label: &'static str,
-    command: &'static str,
-    args: &'static [&'static str],
-    install_instructions_url: &'static str,
-    install_hint: &'static str,
-    /// Vendor CLI the ACP command wraps, when the preset is an adapter
-    /// (e.g. Amp's `amp-acp` wraps the separately-installed `amp` CLI).
-    /// Consulted only when the adapter is absent, so `AdapterMissing`
-    /// replaces the misleading `NotInstalled` when the CLI is present but
-    /// the adapter is not. Deliberately NOT fed through the builtins'
-    /// full `classify_runtime` predicate: that would flip
-    /// adapter-present/CLI-absent from today's `Available` to `CliMissing`
-    /// (unselectable), and presets carry a single flat `install_hint`, so
-    /// the `CliMissing` copy would tell the user to install the adapter
-    /// they already have. `None` when the command IS the vendor CLI.
-    underlying_cli: Option<&'static str>,
-}
-
-/// Build the catalog entry for one preset harness through an injectable
-/// resolver — the seam the preset loop consumes and tests bind.
-///
-/// Availability consumes only the adapter-missing arm of the builtin
-/// predicate: adapter presence alone decides `Available` (exactly today's
-/// behavior — an `amp-acp` without `amp` stays selectable), and
-/// `underlying_cli` is consulted only when the adapter is absent, to
-/// distinguish `AdapterMissing` (vendor CLI present) from `NotInstalled`
-/// (neither found). See the `underlying_cli` field doc for why the full
-/// `classify_runtime` predicate is deliberately not used here.
-fn preset_catalog_entry(
-    def: &PresetHarness,
-    resolve: impl Fn(&str) -> Option<PathBuf>,
-) -> AcpRuntimeCatalogEntry {
-    let (availability, command, binary_path) = match resolve(def.command) {
-        Some(path) => (
-            AcpAvailabilityStatus::Available,
-            Some(def.command.to_string()),
-            Some(path.display().to_string()),
-        ),
-        None => {
-            let underlying_cli_found = def
-                .underlying_cli
-                .map(|cli| resolve(cli).is_some())
-                .unwrap_or(false);
-            if underlying_cli_found {
-                (AcpAvailabilityStatus::AdapterMissing, None, None)
-            } else {
-                (AcpAvailabilityStatus::NotInstalled, None, None)
-            }
-        }
-    };
-    let underlying_cli_path = def
-        .underlying_cli
-        .and_then(resolve)
-        .map(|p| p.display().to_string());
-
-    let default_args = normalize_agent_args(
-        def.command,
-        def.args.iter().map(|s| s.to_string()).collect(),
-    );
-
-    AcpRuntimeCatalogEntry {
-        id: def.id.to_string(),
-        label: def.label.to_string(),
-        // No remote URL — all preset icons are bundled assets.
-        avatar_url: String::new(),
-        availability,
-        command,
-        binary_path,
-        default_args,
-        mcp_command: None,
-        model_env_var: None,
-        provider_env_var: None,
-        thinking_env_var: None,
-        install_hint: def.install_hint.to_string(),
-        install_instructions_url: def.install_instructions_url.to_string(),
-        can_auto_install: false,
-        // Kept false even for adapter presets: presets carry one flat
-        // install_hint (the adapter's), so the requiresExternalCli
-        // "CLI is missing" wording would pair the wrong noun with it.
-        // The builtin path, with per-availability hints, is the only
-        // consumer of the true case.
-        requires_external_cli: false,
-        underlying_cli_path,
-        node_required: false,
-        auth_status: AuthStatus::NotApplicable,
-        login_hint: None,
-        source: HarnessSource::Preset,
-        // Preset entries have static, non-editable env; definition_env is empty.
-        definition_env: Default::default(),
-    }
-}
+// Tier-2 preset harnesses (static PRESET_HARNESSES catalog, bundled logos,
+// no PATH-installer) live in `presets.rs` — split out to keep this file
+// under the desktop file-size ratchet as the preset list grows.
+mod presets;
 
-const PRESET_HARNESSES: &[PresetHarness] = &[
-    PresetHarness {
-        id: "cursor",
-        label: "Cursor",
-        command: "cursor-agent",
-        args: &["acp"],
-        install_instructions_url: "https://cursor.com/downloads",
-        install_hint: "Buzz talks to Cursor through the cursor-agent CLI's ACP mode.",
-        underlying_cli: None,
-    },
-    PresetHarness {
-        id: "omp",
-        label: "Oh My Pi",
-        command: "omp",
-        args: &["acp"],
-        install_instructions_url: "https://github.com/can1357/oh-my-pi",
-        install_hint: "Buzz talks to Oh My Pi through its CLI's ACP mode (omp acp).",
-        underlying_cli: None,
-    },
-    PresetHarness {
-        id: "grok",
-        label: "Grok Build",
-        command: "grok",
-        args: &["agent", "--always-approve", "stdio"],
-        install_instructions_url: "https://build.x.ai/docs",
-        install_hint: "Buzz talks to Grok Build through its CLI's agent stdio mode.",
-        underlying_cli: None,
-    },
-    PresetHarness {
-        id: "opencode",
-        label: "OpenCode",
-        command: "opencode",
-        args: &["acp"],
-        install_instructions_url: "https://opencode.ai/docs",
-        install_hint: "Buzz talks to OpenCode through its CLI's ACP mode (opencode acp).",
-        underlying_cli: None,
-    },
-    PresetHarness {
-        id: "kimi",
-        label: "Kimi Code",
-        command: "kimi",
-        args: &["acp"],
-        install_instructions_url: "https://kimi.ai/download",
-        install_hint: "Buzz talks to Kimi Code through its CLI's ACP mode (kimi acp).",
-        underlying_cli: None,
-    },
-    PresetHarness {
-        id: "amp",
-        label: "Amp",
-        command: "amp-acp",
-        args: &[],
-        install_instructions_url: "https://github.com/tao12345666333/amp-acp",
-        install_hint: "Buzz talks to the Amp CLI through the amp-acp adapter. Follow the setup guide to install the adapter so the amp-acp command is on your PATH.",
-        underlying_cli: Some("amp"),
-    },
-    PresetHarness {
-        id: "hermes",
-        label: "Hermes Agent",
-        command: "hermes-acp",
-        args: &[],
-        install_instructions_url: "https://hermes-agent.nousresearch.com",
-        install_hint: "Buzz talks to Hermes Agent through its hermes-acp command.",
-        underlying_cli: None,
-    },
-    PresetHarness {
-        id: "openclaw",
-        label: "OpenClaw",
-        command: "openclaw",
-        args: &["acp"],
-        install_instructions_url: "https://docs.openclaw.ai/start/getting-started",
-        install_hint: "Buzz talks to OpenClaw through its ACP mode (openclaw acp), which relies on the OpenClaw Gateway daemon. Follow the setup guide to install both.\n\n\
-            ⚠️  Execution-locus note: `openclaw acp` runs tools inside the \
-            OpenClaw Gateway daemon, not in the Desktop process. \
-            Desktop-injected BUZZ_* env vars are visible to the `openclaw` \
-            harness process itself, but do NOT automatically reach the \
-            Gateway's execution environment. If your tools or agent logic \
-            needs BUZZ_* credentials at execution time, set them on the \
-            Gateway's own environment separately.",
-        underlying_cli: None,
-    },
-];
-
-/// Return the static preset harness definitions as `HarnessDefinition` values.
-///
-/// Used by `warm_harness_registry_from_dir` to seed the loaded-harness registry
-/// at startup before the frontend triggers a full discovery run.
-pub(crate) fn preset_harness_definitions(
-) -> Vec<crate::managed_agents::custom_harnesses::HarnessDefinition> {
-    PRESET_HARNESSES
-        .iter()
-        .map(
-            |p| crate::managed_agents::custom_harnesses::HarnessDefinition {
-                id: p.id.to_string(),
-                label: p.label.to_string(),
-                command: p.command.to_string(),
-                args: p.args.iter().map(|s| s.to_string()).collect(),
-                env: std::collections::BTreeMap::new(),
-                install_instructions_url: p.install_instructions_url.to_string(),
-                install_hint: p.install_hint.to_string(),
-            },
-        )
-        .collect()
-}
-
-/// Return the static slice of preset harness IDs.
-///
-/// Used by `check_id_collision` in `custom_harnesses` to derive the reserved-ID
-/// set from the single source of truth (`PRESET_HARNESSES`) rather than a
-/// hand-maintained copy.  Adding a preset automatically reserves its ID.
-pub(crate) fn preset_harness_ids() -> &'static [&'static str] {
-    // `PRESET_HARNESSES` is `'static`; we project its `id` fields.
-    // Computed once via OnceLock to avoid repeated allocations on hot paths.
-    use std::sync::OnceLock;
-    static IDS: OnceLock<Vec<&'static str>> = OnceLock::new();
-    IDS.get_or_init(|| PRESET_HARNESSES.iter().map(|p| p.id).collect())
-        .as_slice()
-}
+use presets::{preset_catalog_entry, PRESET_HARNESSES};
+pub(crate) use presets::{preset_harness_definitions, preset_harness_ids};
 
 /// Discover all ACP runtimes, optionally merging user-defined custom harnesses
 /// from `custom_harnesses_dir`.