test(core): reproduce hot reload regressions - #37427

What

Adds deterministic red tests for two V2 hot-reload blockers:

• update events can be observed before the corresponding rebuilt state is readable (Catalog update events can precede readable state #37422)
• importing @opencode-ai/core/skill first in a fresh process crashes through an ESM initialization cycle (Importing the public skill module first crashes through an ESM cycle #37424)
• changes inside watched config directories are ignored when parsed config entries remain equal (Changes inside config directories do not trigger config-backed reloads #37429)

This is intentionally a draft, red-test PR. It establishes the contracts and keeps the failures visible while fixes are developed separately.

Before / After

Before

A domain rebuild calls its State.finalize callback, the callback publishes *.updated, and only afterward does State assign the rebuilt snapshot. A client reacting to the event can immediately refetch the previous agent, command, skill-source, or provider/model catalog.

A fresh process importing the public skill module can enter skill -> permission -> session -> skill; Session.SkillNotFoundError eagerly reads SkillV2.ID while that binding is still uninitialized.

A watcher update for .opencode/commands/review.md rediscovers the same Config entry list, so Config.reload returns before publishing config.updated; config-backed plugins never rescan the changed file.

After this test PR

The required behavior is executable and currently red:

• every observed update event must imply that the corresponding read API exposes the new snapshot
• every public Core module must be safe to import first in a fresh process

How

• packages/core/test/agent.test.ts reads the registered agent immediately after agent.updated.
• packages/core/test/command.test.ts reads the registered command immediately after command.updated.
• packages/core/test/skill.test.ts reads registered skill sources immediately after skill.updated.
• packages/core/test/catalog.test.ts reads the provider immediately after catalog.updated.
• packages/core/test/config/config.test.ts publishes a watcher update for a file inside a Config directory and waits for config.updated.
• packages/core/test/public-import.test.ts imports @opencode-ai/core/skill in a fresh Bun process so module caching cannot hide the cycle.

sequenceDiagram
    participant State
    participant Events
    participant Client
    participant API

    State->>State: build next snapshot
    State->>Events: publish *.updated
    Events->>Client: invalidate catalog
    Client->>API: list immediately
    API-->>Client: previous snapshot
    State->>State: assign next snapshot

Scope

This PR does not fix either failure and is not merge-ready while the tests are red.

Missing but non-regressed hot-reload surfaces are tracked separately:

• MCP server config: Hot reload MCP server configuration #37421
• external TUI config and custom themes: Hot reload external TUI configuration and custom themes #37423
• TUI plugin config and local sources: Hot reload TUI plugin configuration and local sources #37425
• global, external, and HTTP skill sources: Refresh global, external, and HTTP skill sources without restart #37426

Testing

Expected red tests:

bun run --cwd packages/core test test/agent.test.ts --test-name-pattern "after agent changes are visible"
bun run --cwd packages/core test test/catalog.test.ts --test-name-pattern "after catalog changes are visible"
bun run --cwd packages/core test test/command.test.ts --test-name-pattern "after command changes are visible"
bun run --cwd packages/core test test/skill.test.ts --test-name-pattern "after skill source changes are visible"
bun run --cwd packages/core test test/config/config.test.ts --test-name-pattern "changed files inside config directories"
bun run --cwd packages/core test test/public-import.test.ts

The first four observe the previous snapshot. The Config test times out waiting for config.updated. The public-import test observes ReferenceError: Cannot access 'ID' before initialization.

Passing validation:

bun turbo typecheck --concurrency=3
bunx prettier --check packages/core/test/agent.test.ts packages/core/test/catalog.test.ts packages/core/test/command.test.ts packages/core/test/skill.test.ts packages/core/test/config/config.test.ts packages/core/test/public-import.test.ts
git diff --check