Use explicit ts specifiers for declarations

Restore explicit .ts relative specifiers in source and enable rewriteRelativeImportExtensions so emitted JS uses .js while declarations keep explicit .ts specifiers. Add a NodeNext declaration-consumer gate to prevent extensionless declaration regressions.

packages/core/agent-loop/src/agent.ts

@@ -11,8 +11,8 @@ import type { AgentId, AgentOptions, AgentStatus, SendOptions } from '@deepseek-
 import type { Agent } from '@deepseek-ai/dsh-agent'
 import type { ContentBlock, MessageSource } from '@deepseek-ai/dsh-llm'
 import type { Session } from '@deepseek-ai/dsh-session'
-import { Inbox } from './inbox'
-import { isTurnOpen, lastTurnNumber, runLoop } from './loop'
+import { Inbox } from './inbox.ts'
+import { isTurnOpen, lastTurnNumber, runLoop } from './loop.ts'
 
 /**
  * The concrete {@link Agent} implementation owned by the agent-loop plugin.

packages/core/agent-loop/src/index.ts

@@ -17,11 +17,11 @@ import type { Session } from '@deepseek-ai/dsh-session'
 import type {} from '@deepseek-ai/dsh-system-prompt'
 import type {} from '@deepseek-ai/dsh-tools'
 import type { SessionPersistence } from '@deepseek-ai/dsh-session-persistence'
-import { ReactLoopAgent } from './agent'
+import { ReactLoopAgent } from './agent.ts'
 
-export { ReactLoopAgent } from './agent'
-export { Inbox, type InboxMessage } from './inbox'
-export { runLoop } from './loop'
+export { ReactLoopAgent } from './agent.ts'
+export { Inbox, type InboxMessage } from './inbox.ts'
+export { runLoop } from './loop.ts'
 
 declare module 'cordis' {
   interface Context {

packages/core/agent-loop/src/loop.ts

@@ -13,7 +13,7 @@ import { BlockAssembler, HarnessError } from '@deepseek-ai/dsh-llm'
 import type { Session, TurnEndReason, TurnTrigger } from '@deepseek-ai/dsh-session'
 import { renderPrompt } from '@deepseek-ai/dsh-system-prompt'
 import type {} from '@deepseek-ai/dsh-tools'
-import type { ReactLoopAgent } from './agent'
+import type { ReactLoopAgent } from './agent.ts'
 
 /** An Error with an optional machine-readable code (e.g., from LlmError or a throwing plugin). */
 type CodedError = Error & { code?: string }