feat(invariants): dev-mode event-contract assertions + session-log freeze (RFC 005 pt 3, RFC 008)
New @deepseek-ai/dsh-invariants plugin (pure listeners, off in prod) asserts the event taxonomy at runtime — seq monotonicity, turn/step nesting, a tool/result needs a prior tool/call (NOT the converse), legal agent/status transitions — and deep-freezes logged event data so mutating history throws. Seeded sessions are checked + frozen on session/created. The real RFC 008 fix is always-on: deriveMessages now structured-clones the content it emits, so the loop's sanctioned request/adapter mutation can no longer reach back and rewrite the append-only log. The pervasive DeepReadonly<T> type flip is rejected (compile-only, high-noise, castable) — recorded in ADR 0012, which folds in RFC 008. Wired into both demos.
This commit is contained in:
Tianyi Cui
239
packages/invariants/tests/invariants.spec.ts
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239
packages/invariants/tests/invariants.spec.ts
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import { describe, expect, it, vi } from 'vitest'
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import { Context } from 'cordis'
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import { CallId } from '@deepseek-ai/dsh-llm'
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import type { Agent } from '@deepseek-ai/dsh-agent'
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import SessionStore from '@deepseek-ai/dsh-session'
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import Invariants, { InvariantError } from '@deepseek-ai/dsh-invariants'
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/** A Context with the session store and the invariants plugin registered. */
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async function setup(config?: { freeze?: boolean }) {
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const ctx = new Context()
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await ctx.plugin(SessionStore)
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const fiber = await ctx.plugin(Invariants, config ?? {})
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return { ctx, fiber }
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}
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/** A minimal Agent stand-in for agent/status emission. */
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function mockAgent(id: string): Agent {
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return { id } as unknown as Agent
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}
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describe('session-log invariants', () => {
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it('accepts a well-formed turn/step/tool sequence', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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expect(() => {
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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session.append('user/message', { content: [{ type: 'text', text: 'hi' }], source: { kind: 'user' } })
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session.append('step/start', { turn: 1, step: 1 })
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session.append('assistant/chunk', { turn: 1, step: 1, chunk: { type: 'text-delta', index: 0, text: 'h' } })
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session.append('assistant/message', { turn: 1, step: 1, content: [{ type: 'tool-call', id: CallId('c1'), name: 'echo', arguments: '{}' }] })
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session.append('tool/call', { turn: 1, step: 1, callId: CallId('c1'), name: 'echo', arguments: '{}' })
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session.append('tool/result', { turn: 1, step: 1, callId: CallId('c1'), content: [{ type: 'text', text: 'ok' }], isError: false })
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session.append('step/end', { turn: 1, step: 1 })
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session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
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}).not.toThrow()
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})
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it('rejects a turn/start while another turn is open', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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expect(() => session.append('turn/start', { turn: 2, trigger: { kind: 'message', source: { kind: 'user' } } }))
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.toThrow(/turn 1 is still open/)
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})
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it('rejects a turn/end that does not match the open turn', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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expect(() => session.append('turn/end', { turn: 2, reason: { kind: 'completed' } }))
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.toThrow(/does not match open turn 1/)
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})
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it('rejects a step/start outside its declared turn', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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expect(() => session.append('step/start', { turn: 2, step: 1 })).toThrow(/open turn is 1/)
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})
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it('rejects a step/end that does not match the open step', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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session.append('step/start', { turn: 1, step: 1 })
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expect(() => session.append('step/end', { turn: 1, step: 2 })).toThrow(/does not match open step 1/)
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})
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it('rejects an assistant/chunk outside an open step', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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expect(() => session.append('assistant/chunk', { turn: 1, step: 1, chunk: { type: 'text-delta', index: 0, text: 'x' } }))
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.toThrow(/outside an open step/)
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})
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it('rejects a tool/result with no prior tool/call', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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session.append('step/start', { turn: 1, step: 1 })
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expect(() => session.append('tool/result', { turn: 1, step: 1, callId: CallId('ghost'), content: [], isError: false }))
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.toThrow(/no prior tool\/call/)
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})
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it('allows a tool/call with no matching tool/result (thrown waterfall ends the step)', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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expect(() => {
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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session.append('step/start', { turn: 1, step: 1 })
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session.append('tool/call', { turn: 1, step: 1, callId: CallId('c1'), name: 'echo', arguments: '{}' })
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session.append('step/end', { turn: 1, step: 1 })
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session.append('turn/end', { turn: 1, reason: { kind: 'error', message: 'boom' } })
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}).not.toThrow()
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})
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it('holds seeded sessions to the contract on session/created', async () => {
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const { ctx } = await setup({ freeze: false })
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// A seed whose seq is non-monotonic must be rejected when the session is
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// created (the constructor copies the seed without emitting session/event).
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const badSeed = [
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{ type: 'turn/start' as const, seq: 0, time: 0, data: { turn: 1, trigger: { kind: 'message' as const, source: { kind: 'user' as const } } } },
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{ type: 'turn/start' as const, seq: 0, time: 0, data: { turn: 2, trigger: { kind: 'message' as const, source: { kind: 'user' as const } } } },
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]
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expect(() => ctx.sessions.create(undefined, badSeed)).toThrow(InvariantError)
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})
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it('tracks turns per session independently', async () => {
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const { ctx } = await setup({ freeze: false })
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const a = ctx.sessions.create('a')
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const b = ctx.sessions.create('b')
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a.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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// b is a fresh session — its own turn/start must not see a's open turn.
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expect(() => b.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })).not.toThrow()
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})
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})
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describe('dev-freeze', () => {
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it('freezes appended event data so mutating a logged event throws', async () => {
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const { ctx } = await setup() // freeze defaults true
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const session = ctx.sessions.create()
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const event = session.append('user/message', { content: [{ type: 'text', text: 'hi' }], source: { kind: 'user' } })
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expect(Object.isFrozen(event)).toBe(true)
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expect(Object.isFrozen(event.data)).toBe(true)
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expect(Object.isFrozen(event.data.content)).toBe(true)
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expect(() => { (event.data.content[0] as { text: string }).text = 'HACKED' }).toThrow()
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})
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it('does not freeze when freeze:false', async () => {
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const { ctx } = await setup({ freeze: false })
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const session = ctx.sessions.create()
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const event = session.append('user/message', { content: [{ type: 'text', text: 'hi' }], source: { kind: 'user' } })
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expect(Object.isFrozen(event)).toBe(false)
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})
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it('freezes seeded events on session/created', async () => {
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const { ctx } = await setup()
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const seed = [
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{ type: 'user/message' as const, seq: 0, time: 0, data: { content: [{ type: 'text' as const, text: 'seeded' }], source: { kind: 'user' as const } } },
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]
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const session = ctx.sessions.create(undefined, seed)
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expect(Object.isFrozen(session.events[0])).toBe(true)
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})
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it('is idempotent over already-frozen sub-structures', async () => {
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const { ctx } = await setup()
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const session = ctx.sessions.create()
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// Pre-freeze a block before appending; deepFreeze must short-circuit on it
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// (the already-frozen guard) while still freezing the enclosing event.
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const block = Object.freeze({ type: 'text' as const, text: 'pre-frozen' })
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const event = session.append('user/message', { content: [block], source: { kind: 'user' } })
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expect(Object.isFrozen(event)).toBe(true)
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expect(Object.isFrozen(event.data.content)).toBe(true)
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expect(Object.isFrozen(event.data.content[0])).toBe(true)
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})
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})
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describe('agent status invariants', () => {
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it('accepts legal transitions: idle→running→idle and →disposed', async () => {
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const { ctx } = await setup({ freeze: false })
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const agent = mockAgent('a1')
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expect(() => {
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ctx.emit('agent/status', agent, 'idle')
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ctx.emit('agent/status', agent, 'running')
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ctx.emit('agent/status', agent, 'idle')
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ctx.emit('agent/status', agent, 'disposed')
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}).not.toThrow()
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})
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it('accepts running→disposed', async () => {
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const { ctx } = await setup({ freeze: false })
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const agent = mockAgent('a2')
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ctx.emit('agent/status', agent, 'running')
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expect(() => { ctx.emit('agent/status', agent, 'disposed') }).not.toThrow()
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})
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it('rejects a no-op transition', async () => {
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const { ctx } = await setup({ freeze: false })
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const agent = mockAgent('a3')
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ctx.emit('agent/status', agent, 'running')
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expect(() => { ctx.emit('agent/status', agent, 'running') }).toThrow(/no-op transition/)
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})
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it('rejects leaving the terminal disposed state', async () => {
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const { ctx } = await setup({ freeze: false })
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const agent = mockAgent('a4')
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ctx.emit('agent/status', agent, 'disposed')
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expect(() => { ctx.emit('agent/status', agent, 'idle') }).toThrow(/left terminal state disposed/)
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})
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it('tracks status per agent independently', async () => {
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const { ctx } = await setup({ freeze: false })
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const a = mockAgent('a5')
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const b = mockAgent('b5')
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ctx.emit('agent/status', a, 'running')
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// b's first observation is independent of a.
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expect(() => { ctx.emit('agent/status', b, 'running') }).not.toThrow()
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})
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})
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describe('HMR safety', () => {
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it('removes all listeners when the plugin fiber is disposed', async () => {
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const { ctx, fiber } = await setup()
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const session = ctx.sessions.create()
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session.append('turn/start', { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } })
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await fiber.dispose()
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// After disposal: no freezing, no assertions. An event that WOULD have
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// violated the open-turn rule now passes silently, and is not frozen.
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const event = session.append('turn/start', { turn: 2, trigger: { kind: 'message', source: { kind: 'user' } } })
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expect(Object.isFrozen(event)).toBe(false)
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// A no-op status transition no longer throws either.
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const agent = mockAgent('hmr')
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ctx.emit('agent/status', agent, 'idle')
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expect(() => { ctx.emit('agent/status', agent, 'idle') }).not.toThrow()
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})
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it('InvariantError carries a stable code', () => {
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const err = new InvariantError('seq must strictly increase')
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expect(err).toBeInstanceOf(Error)
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expect(err.name).toBe('InvariantError')
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expect(err.code).toBe('INVARIANT')
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expect(err.message).toBe('invariant violated: seq must strictly increase')
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})
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it('does not leak listeners across dispose (no stale freezing)', async () => {
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const { ctx, fiber } = await setup()
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await fiber.dispose()
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const spy = vi.fn()
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ctx.on('session/event', spy)
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const session = ctx.sessions.create()
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session.append('user/message', { content: [{ type: 'text', text: 'x' }], source: { kind: 'user' } })
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// our own spy fires, proving events still flow — but the plugin's frozen.
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expect(spy).toHaveBeenCalledOnce()
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expect(Object.isFrozen(session.events[0])).toBe(false)
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})
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})
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