feat(gemini): remove launchable Gemini CLI agent, keep old sessions readable (#953)

* feat(gemini): remove launchable Gemini CLI agent, keep sessions readable

Google sunset the consumer Gemini CLI (Pro/Ultra/free tiers stopped
serving requests 2026-06-18). This removes the ability to launch/create
Gemini CLI sessions while keeping existing stored Gemini sessions fully
readable in the web UI.

Removed (no longer launchable):
- cli/src/gemini/ runtime (runGemini, loop, local/remote launchers,
  session, ACP backend, config, scanner) + GeminiDisplay ink view
- `hapi gemini` command + registry entry + usage line
- runner spawn branch & buildCliArgs mapping now reject gemini with a
  clear error; resume dispatch throws a clear "no longer supported" error
- gemini dropped from the new-session agent selector via new
  CREATABLE_AGENT_FLAVORS, and from preferred-agent defaults

Kept (read path — existing sessions still validate, load, render):
- `gemini` in AGENT_FLAVORS / AgentFlavorSchema, FLAVOR_CAPS / FLAVOR_LABELS
- AgentFlavorIcon badge, model-option labels, ACP message normalization,
  metadata.geminiSessionId, hub session dedup/resume-id

Note: the Gemini *Live voice* backend is a separate feature and is
untouched.

Adds read-guarantee tests (stored gemini validates; excluded from
creatable). typecheck + full suite green.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(gemini): reject gemini resume before handoff (#953 review)

HAPI Bot [Major]: `hapi resume <active-gemini-session>` called
handoffSessionToLocal() — which tells the running remote agent to exit —
before reaching the gemini-unsupported throw in dispatchLocalResume, so
it could stop the live/readable session and then fail locally.

Move the gemini guard into resumeCommand.run before the handoff, so an
active Gemini session is left running/readable instead of being stopped.
Keep the dispatch-layer guard as defense-in-depth. Adds a regression test
asserting handoffSessionToLocal is not called for an active gemini target.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(gemini): harden against stale gemini input (#953 review)

Two [Minor] follow-ups from HAPI Bot:
- newSessionFormDraft: coerce a restored browse draft's agent to a
  creatable flavor, so a pre-removal 'gemini' draft cannot submit
  agent:'gemini' even though the selector no longer offers it.
- buildCliArgs: reject 'gemini' explicitly instead of silently falling
  through to the 'claude' command if the exported helper is reused
  outside the guarded spawnSession path.

Updated the buildCliArgs precedence test to a creatable agent and added
a test asserting buildCliArgs('gemini') throws.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(gemini): reset dependent draft fields when coercing stale agent (#953 review)

Follow-up [Minor]: coercing a stale gemini draft's agent to claude left
model/base/effort untouched, so a { agent:'gemini', model:'gemini-2.5-pro' }
draft restored as claude *with* a Gemini model, which handleCreate() then
sent to the runner. Now reset model / cursorSelectedBase / effort /
modelReasoningEffort to defaults whenever the agent is coerced.

Adds a regression test.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* fix(gemini): tombstone `hapi gemini` so it errors clearly (#953 review)

HAPI Bot [Major]: after removing geminiCommand from the registry,
resolveCommand() treats `gemini` as an unknown subcommand and falls
through to the default Claude command (forwarding "gemini" as an arg),
so `hapi gemini` silently started Claude instead of reporting the sunset.

Add an explicit tombstone `gemini` command that prints the sunset error
and exits 1.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* test(web): assert AgentSelector hides the sunset Gemini agent (#953)

Render regression test confirming the new-session AgentSelector offers
exactly CREATABLE_AGENT_FLAVORS and never shows a Gemini radio.

via [HAPI](https://hapi.run)

Co-Authored-By: HAPI <noreply@hapi.run>
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

---------

Co-authored-by: HAPI <noreply@hapi.run>
Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

cli/src/runner/run.ts

@@ -287,6 +287,9 @@ export async function startRunner(options: { workspaceRoots?: string[] } = {}):
 
       const { directory, sessionId, machineId, approvedNewDirectoryCreation = true } = options;
       const agent = options.agent ?? 'claude';
+      if (agent === 'gemini') {
+        throw new Error('Gemini CLI is no longer supported and cannot be launched (Google sunset the consumer Gemini CLI on 2026-06-18). Existing Gemini sessions remain viewable in the web UI.');
+      }
       const yolo = options.yolo === true;
       const sessionType = options.sessionType ?? 'simple';
       const worktreeName = options.worktreeName;
@@ -1073,19 +1076,20 @@ export function buildCliArgs(
   options: SpawnSessionOptions,
   yolo?: boolean
 ): string[] {
+  if (agent === 'gemini') {
+    throw new Error('Gemini CLI is no longer supported and cannot be launched (Google sunset the consumer Gemini CLI on 2026-06-18).');
+  }
   const agentCommand = agent === 'codex'
     ? 'codex'
     : agent === 'cursor'
       ? 'cursor'
-      : agent === 'gemini'
-        ? 'gemini'
-        : agent === 'kimi'
-          ? 'kimi'
-          : agent === 'opencode'
-            ? 'opencode'
-            : agent === 'pi'
-              ? 'pi'
-              : 'claude';
+      : agent === 'kimi'
+        ? 'kimi'
+        : agent === 'opencode'
+          ? 'opencode'
+          : agent === 'pi'
+            ? 'pi'
+            : 'claude';
   const args = [agentCommand];
   if (options.resumeSessionId) {
     if (agent === 'codex') {