## Context

The Agents panel (`omarchy.agents`, `shell/plugins/agents/`) shows AI coding subscription usage in the Omarchy bar — currently Claude Code, Codex, and Fireworks. Gemini CLI and OpenCode are already first-class agents elsewhere in Omarchy (`omarchy-default-agent` supports `gemini` and `opencode` as launchable agents), but neither has a usage collector, so neither appears in the panel even when actively used daily.

## Current State

3 collectors exist (`bin/omarchy-agent-usage-{claude,codex,fireworks}`), declared in `shell/plugins/agents/manifest.json:defaults.providers`. The plugin's own README documents the extension point: *"Adding an agent therefore never touches this plugin: ship a collector... and the panel gains a tab."* No changes to `Panel.qml`/`Main.qml`/`Agent.qml` are required for a new agent.

## Proposed Change

Add two independent collectors, each following the existing display-ready-JSON-record contract:

1. `omarchy-agent-usage-opencode` — reads `~/.local/share/opencode/opencode.db` (SQLite) directly.
2. `omarchy-agent-usage-gemini` — reads Gemini CLI's local session logs, with a best-effort live quota probe against Google's Code Assist endpoint when Gemini CLI is Code-Assist-licensed.

Both register in `shell/plugins/agents/manifest.json:defaults.providers` and get an `assets/<id>.svg` (+ `-light` variant if needed).

## Child Issues

| # | Title | Priority | Effort | Status | Dependencies |
|---|-------|----------|--------|--------|--------------|
| #9683 | Add OpenCode collector to the Agents panel | High | ~4h | Ready | None |
| #9684 | Add Gemini collector to the Agents panel | High | ~6h | Ready | None (independent; sequenced after the OpenCode child by convention, not by blocking) |

## Dependency Graph

```
Epic ─┬─> Child 1: OpenCode collector (independent, ships first)
      └─> Child 2: Gemini collector (independent, ships second)
```

## Sequencing Rationale

OpenCode first: its data source (`opencode.db`) is proven and queryable today, with zero external API uncertainty — no balance API exists for OpenCode Zen (confirmed: anomalyco/opencode#10448 is an open feature request for exactly this, meaning it doesn't exist yet), so v1 ships stats-only with no blocking research. Gemini second: its local session log format (`~/.gemini/tmp/<project-hash>/chats/logs.json`) is undocumented and unverified against a real file, and its live-quota path depends on a Google-side Code Assist license that most personal accounts don't have (verified live: HTTP 403 `SUBSCRIPTION_REQUIRED` against `cloudcode-pa.googleapis.com`) — more research/validation risk, so it ships after the lower-risk child proves the pattern.

## Definition of Done

1. Both collectors merged and each individually shippable/revertable per its own child issue's acceptance criteria.
2. On a machine with OpenCode installed and used, an "OpenCode" tab appears in the panel with real token/day/model data.
3. On a machine with Gemini CLI installed and used, a "Gemini" tab appears in the panel with real token/day/model data, and a live limit bar when the account has a Code Assist license.
4. Neither collector's addition changes Claude, Codex, or Fireworks behavior.

## Out of Scope

- Any change to `Panel.qml`, `Main.qml`, or `Agent.qml`.
- Cost/spend display for OpenCode (data exists in `opencode.db` message rows' `cost` field but surfacing it is a UI change, out of scope here — flagged as a future issue).
- Any agent besides Gemini and OpenCode (Grok, Copilot, Crush, Pi, omp — all already known to `omarchy-default-agent` but not requested here).
- `syncMode` cross-device aggregation changes.

## Related

- Child: #9683 — Add OpenCode collector to the Agents panel
- Child: #9684 — Add Gemini collector to the Agents panel