Enforce 100% per-file test coverage on packages/*/src

vitest coverage (v8 provider) with per-file 100% thresholds for
statements, branches, functions, and lines. Scope: our runtime source
only — types-only files, vendor/ (upstream code), and examples/
(exercised by the demo smoke test) are excluded. yarn test:coverage
runs the gate.

59 tests added to close every gap: llm generate-waterfall and adapter
disposal; assembler edge protocol (duplicate block-start, stragglers
after block-end, id fallback, usage omission, invariant violation);
the whole Inbox surface incl. the wakeup-overwrite race; LoopAgent
disposed-state throws and double-stop idempotence; config-driven agent
creation; loop backstop catches (throwing turn-start/turn-end
listeners, non-Error throws, non-JSON tool arguments); system-prompt
dynamic sections and disposer paths; tools errorMessage fallbacks and
the full schema-DSL emission matrix. Genuinely unreachable defensive
guards carry /* v8 ignore */ comments with stated reasons rather than
deletion (132 tests total).

packages/llm/tests/service.spec.ts

@@ -1,6 +1,6 @@
 import { describe, expect, it } from 'vitest'
 import { Context } from 'cordis'
-import LlmService, { GenerateOptions, LlmAdapter, StreamChunk } from '@deepseek-ai/dsh-llm'
+import LlmService, { GenerateOptions, LlmAdapter, LlmError, StreamChunk } from '@deepseek-ai/dsh-llm'
 
 class ScriptedAdapter extends LlmAdapter {
   constructor(private script: StreamChunk[]) {
@@ -70,4 +70,58 @@ describe('LlmService', () => {
     expect(chunks).toHaveLength(4)
     expect(chunks[0]).toMatchObject({ index: 99 })
   })
+
+  it('lets llm/generate waterfall listeners intercept and transform the result', async () => {
+    const ctx = new Context()
+    await ctx.plugin(LlmService)
+    ctx.llm.registerAdapter(['test-model'], new ScriptedAdapter(SCRIPT))
+
+    ctx.on('llm/generate', async function (_options, next) {
+      const result = await next()
+      return { ...result, finish: { kind: 'max-tokens' } as const }
+    })
+
+    const result = await ctx.llm.generate({ model: 'test-model', messages: [] })
+    expect(result.finish).toEqual({ kind: 'max-tokens' })
+    expect(result.message.content).toEqual([{ type: 'text', text: 'hi' }])
+  })
+
+  it('creates LlmError with a code for programmatic handling', () => {
+    const err = new LlmError('something went wrong', 'CUSTOM_CODE')
+    expect(err).toBeInstanceOf(Error)
+    expect(err.name).toBe('LlmError')
+    expect(err.message).toBe('something went wrong')
+    expect(err.code).toBe('CUSTOM_CODE')
+  })
+
+  it('disposes adapter registration on adapter-change event emission', async () => {
+    const ctx = new Context()
+    await ctx.plugin(LlmService)
+
+    const changes: string[][] = []
+    ctx.on('llm/adapter-change', () => {
+      changes.push([...ctx.llm.models()])
+    })
+
+    const dispose = ctx.llm.registerAdapter(['m1'], new ScriptedAdapter(SCRIPT))
+    expect(changes).toEqual([['m1']])
+
+    dispose()
+    expect(changes).toEqual([['m1'], []])
+    expect(ctx.llm.models()).toEqual([])
+  })
+
+  it('rejects duplicate adapter registration with DUPLICATE_ADAPTER code', async () => {
+    const ctx = new Context()
+    await ctx.plugin(LlmService)
+    ctx.llm.registerAdapter(['m1'], new ScriptedAdapter(SCRIPT))
+    try {
+      ctx.llm.registerAdapter(['m1'], new ScriptedAdapter(SCRIPT))
+      expect.fail('expected error')
+    } catch (error: unknown) {
+      expect(error).toBeInstanceOf(LlmError)
+      expect((error as LlmError).message).toContain('already registered')
+      expect((error as LlmError).code).toBe('DUPLICATE_ADAPTER')
+    }
+  })
 })