feat: add antigravity-cli integration (#2087)

* feat: add antigravity_cli integration harness

Register the `antigravity_cli` target, resolve its configuration
directory to `~/.gemini/antigravity-cli/`, wire target actions,
and add lifecycle hook scripts for Unix and Windows.

* feat: support session resume for antigravity-cli

* fix: correct antigravity-cli hook config path, shape, and agent label

Antigravity CLI reads global customizations from ~/.gemini/config, keys
hooks.json by hook name, and only accepts the matcher/hooks wrapper for
the tool events. The previous install wrote event arrays at the top level
of ~/.gemini/antigravity-cli/hooks.json, which agy never reads and would
reject anyway, so no Herdr hook ever ran.

Session reports were dropped for a third reason: the hooks reported the
agent as antigravity-cli, but the server normalizes that to the canonical
label agy before matching, so is_official_agent_source never matched and
agy --conversation resume was unreachable.

- Resolve the config dir to ~/.gemini/config
- Nest Herdr entries under a Herdr-owned "herdr" block that install
  rewrites and uninstall removes, leaving other named hooks untouched
- Emit grouped entries for PreToolUse/PostToolUse and flat handler lists
  for PreInvocation/PostInvocation/Stop
- Report the canonical agy label from both hook assets and match it in
  agent_resume
- Compile-gate the hook asset constants and stop shadowing $args in the
  PowerShell hook
- Document the real directory, that it must already exist, and the
  named-block behavior

refs #1011
refs #1571

* fix: make antigravity-cli integration session-only

antigravity cli cannot express lifecycle safely: there is no blocked
event, postinvocation is skipped on interruption, and stop fires at the
end of a turn rather than on process exit, which left stale state and
released authority at the wrong time.

report only the conversation on preinvocation and let screen detection
own agent state. resume via `agy --conversation <id>` is unchanged.

* fix: update antigravity session after conversation switch

---------

Co-authored-by: Can Celik <ogulcancelik@gmail.com>

1 files changed, 119 insertions, 94 deletions

diff --git a/src/terminal/state.rs b/src/terminal/state.rs
index e806967e..5ed5adc4 100644
--- a/src/terminal/state.rs
+++ b/src/terminal/state.rs
@@ -1234,7 +1234,7 @@ impl TerminalState {
                     && current_kind == crate::agent_resume::AgentSessionRefKind::Id
                     && session_ref.kind == crate::agent_resume::AgentSessionRefKind::Id
                     && current_value != session_ref.value
-                    && !Self::session_start_source_allows_session_replacement(
+                    && !Self::session_report_allows_session_replacement(
                         source,
                         agent_label,
                         session_start_source,
@@ -1267,7 +1267,7 @@ impl TerminalState {
                 })
     }
 
-    fn session_start_source_allows_session_replacement(
+    fn session_report_allows_session_replacement(
         source: &str,
         agent_label: &str,
         session_start_source: Option<&str>,
@@ -1291,6 +1291,7 @@ impl TerminalState {
                     "omp",
                     Some("startup" | "new" | "resume" | "fork")
                 )
+                | ("herdr:antigravity_cli", "agy", None)
         )
     }
 
@@ -1413,12 +1414,12 @@ impl TerminalState {
         if self.known_agent_label_conflicts_with_detected_agent(&agent_label) {
             return None;
         }
-        let session_replacement_allowed = Self::session_start_source_allows_session_replacement(
+        let session_replacement_allowed = Self::session_report_allows_session_replacement(
             &source,
             &agent_label,
             session_start_source.as_deref(),
         );
-        let replacing_hermes_session =
+        let replacing_identity_only_session =
             crate::detect::session_identity_only_integration(&source, &agent_label)
                 && session_replacement_allowed
                 && self.current_session_identity_for_persistence().is_some_and(
@@ -1430,7 +1431,7 @@ impl TerminalState {
                             && current_value != session_ref.value
                     },
                 );
-        if replacing_hermes_session && !process_present {
+        if replacing_identity_only_session && !process_present {
             return None;
         }
         let owner_conflicts = self.current_session_owner_conflicts(&source, &agent_label);
@@ -2309,101 +2310,125 @@ mod tests {
     }
 
     #[test]
-    fn hermes_session_claim_leaves_state_to_detection() {
-        let mut terminal = test_terminal();
-        terminal.set_detected_state(Some(Agent::Hermes), AgentState::Idle);
-        let session_ref = crate::agent_resume::AgentSessionRef::id("hermes-root").unwrap();
-
-        let session = terminal.set_agent_session_ref_for_session_start(
-            "herdr:hermes".into(),
-            "hermes".into(),
-            Some(session_ref.clone()),
-            Some(10),
-            Some("startup".into()),
-        );
-
-        assert!(session.is_some());
-        assert!(terminal.hook_authority.is_none());
-        assert_eq!(
-            terminal
-                .persisted_agent_session
-                .as_ref()
-                .map(|session| &session.session_ref),
-            Some(&session_ref)
-        );
-
-        terminal.set_detected_state(Some(Agent::Hermes), AgentState::Working);
+    fn session_identity_claims_leave_state_to_detection() {
+        for (source, label, agent, start_source, replacement_source) in [
+            (
+                "herdr:hermes",
+                "hermes",
+                Agent::Hermes,
+                Some("startup"),
+                Some("resume"),
+            ),
+            (
+                "herdr:antigravity_cli",
+                "agy",
+                Agent::Antigravity,
+                None,
+                None,
+            ),
+        ] {
+            let mut terminal = test_terminal();
+            terminal.set_detected_state(Some(agent), AgentState::Idle);
+            let first_ref =
+                crate::agent_resume::AgentSessionRef::id(format!("{label}-root")).unwrap();
+            let first = terminal.set_agent_session_ref_for_session_start(
+                source.into(),
+                label.into(),
+                Some(first_ref.clone()),
+                Some(10),
+                start_source.map(str::to_string),
+            );
 
-        assert_eq!(terminal.state, AgentState::Working);
-        assert!(terminal.hook_authority.is_none());
+            assert!(first.is_some(), "{label} should accept its session");
+            assert!(terminal.hook_authority.is_none());
+            assert_eq!(terminal.state, AgentState::Idle);
+            assert_eq!(
+                terminal
+                    .persisted_agent_session
+                    .as_ref()
+                    .map(|session| &session.session_ref),
+                Some(&first_ref)
+            );
 
-        let replacement_ref =
-            crate::agent_resume::AgentSessionRef::id("hermes-replacement").unwrap();
-        let replacement = terminal.set_agent_session_ref_for_session_start(
-            "herdr:hermes".into(),
-            "hermes".into(),
-            Some(replacement_ref.clone()),
-            Some(11),
-            Some("startup".into()),
-        );
+            terminal.set_detected_state(Some(agent), AgentState::Working);
+            let replacement_ref =
+                crate::agent_resume::AgentSessionRef::id(format!("{label}-replacement")).unwrap();
+            let replacement = terminal.set_agent_session_ref_for_session_start(
+                source.into(),
+                label.into(),
+                Some(replacement_ref.clone()),
+                Some(11),
+                start_source.map(str::to_string),
+            );
 
-        assert!(replacement.is_some());
-        assert_eq!(terminal.state, AgentState::Working);
-        assert!(terminal.hook_authority.is_none());
-        assert_eq!(
-            terminal
-                .persisted_agent_session
-                .as_ref()
-                .map(|session| &session.session_ref),
-            Some(&replacement_ref)
-        );
+            assert!(
+                replacement.is_some_and(|mutation| mutation.session_ref_changed),
+                "{label} should replace its detected session"
+            );
+            assert!(terminal.hook_authority.is_none());
+            assert_eq!(terminal.state, AgentState::Working);
+            assert_eq!(
+                terminal
+                    .persisted_agent_session
+                    .as_ref()
+                    .map(|session| &session.session_ref),
+                Some(&replacement_ref)
+            );
 
-        let legacy_state = terminal.set_hook_authority_with_session_ref(
-            "herdr:hermes".into(),
-            "hermes".into(),
-            AgentState::Blocked,
-            None,
-            Some(replacement_ref.clone()),
-            Some(12),
-        );
-        assert!(legacy_state.is_none());
-        assert_eq!(terminal.state, AgentState::Working);
-        assert!(terminal.hook_authority.is_none());
+            let legacy_state = terminal.set_hook_authority_with_session_ref(
+                source.into(),
+                label.into(),
+                AgentState::Blocked,
+                None,
+                Some(replacement_ref.clone()),
+                Some(12),
+            );
+            assert!(legacy_state.is_none());
+            assert!(terminal.hook_authority.is_none());
+            assert_eq!(terminal.state, AgentState::Working);
 
-        terminal.set_detected_state(None, AgentState::Unknown);
-        let background_replacement = terminal.set_agent_session_ref_for_session_start(
-            "herdr:hermes".into(),
-            "hermes".into(),
-            crate::agent_resume::AgentSessionRef::id("hermes-background"),
-            Some(13),
-            Some("resume".into()),
-        );
-        assert!(background_replacement.is_none());
-        assert_eq!(
-            terminal
-                .persisted_agent_session
-                .as_ref()
-                .map(|session| &session.session_ref),
-            Some(&replacement_ref)
-        );
+            terminal.set_detected_state(None, AgentState::Unknown);
+            let background_ref =
+                crate::agent_resume::AgentSessionRef::id(format!("{label}-background")).unwrap();
+            let background_replacement = terminal.set_agent_session_ref_for_session_start(
+                source.into(),
+                label.into(),
+                Some(background_ref.clone()),
+                Some(13),
+                replacement_source.map(str::to_string),
+            );
+            assert!(
+                background_replacement.is_none(),
+                "{label} should reject a background replacement"
+            );
+            assert_eq!(
+                terminal
+                    .persisted_agent_session
+                    .as_ref()
+                    .map(|session| &session.session_ref),
+                Some(&replacement_ref)
+            );
 
-        terminal.set_detected_state(Some(Agent::Hermes), AgentState::Idle);
-        let retried_ref = crate::agent_resume::AgentSessionRef::id("hermes-background").unwrap();
-        let retried_replacement = terminal.set_agent_session_ref_for_session_start(
-            "herdr:hermes".into(),
-            "hermes".into(),
-            Some(retried_ref.clone()),
-            Some(14),
-            Some("resume".into()),
-        );
-        assert!(retried_replacement.is_some());
-        assert_eq!(
-            terminal
-                .persisted_agent_session
-                .as_ref()
-                .map(|session| &session.session_ref),
-            Some(&retried_ref)
-        );
+            terminal.set_detected_state(Some(agent), AgentState::Idle);
+            let retried_replacement = terminal.set_agent_session_ref_for_session_start(
+                source.into(),
+                label.into(),
+                Some(background_ref.clone()),
+                Some(14),
+                replacement_source.map(str::to_string),
+            );
+            assert!(
+                retried_replacement.is_some_and(|mutation| mutation.session_ref_changed),
+                "{label} should replace the session once detected"
+            );
+            assert_eq!(
+                terminal
+                    .persisted_agent_session
+                    .as_ref()
+                    .map(|session| &session.session_ref),
+                Some(&background_ref)
+            );
+        }
     }
 
     #[test]