Implement the agent loop plugin

@deepseek-ai/dsh-agent-loop: LoopAgent (inbox with queued + steering
FIFOs, per-step AbortController) and the streaming-first
session/turn/step loop. Extension seams: agent/request,
agent/step-result, agent/turn-continuation waterfalls; raw chunks
logged for replay while BlockAssembler builds the assembled message;
steering drains between steps; session/flush awaited at turn end.

16 tests with a scripted mock adapter cover turn lifecycle ordering,
tool round-trips, steering, inject(), continuation override/veto,
mid-stream abort, queued turn chaining, replay equivalence, and
mid-turn fiber disposal (HMR safety).

packages/agent-loop/package.json

@@ -0,0 +1,41 @@
+{
+  "name": "@deepseek-ai/dsh-agent-loop",
+  "description": "The concrete agent loop plugin for the DeepSeek Harness",
+  "version": "0.0.1",
+  "private": true,
+  "type": "module",
+  "main": "lib/index.js",
+  "types": "lib/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./lib/index.d.ts",
+      "default": "./lib/index.js"
+    },
+    "./src/*": "./src/*",
+    "./package.json": "./package.json"
+  },
+  "files": [
+    "lib",
+    "src"
+  ],
+  "license": "BSD-3-Clause",
+  "peerDependencies": {
+    "@deepseek-ai/dsh-agent": "^0.0.1",
+    "@deepseek-ai/dsh-llm": "^0.0.1",
+    "@deepseek-ai/dsh-session": "^0.0.1",
+    "@deepseek-ai/dsh-system-prompt": "^0.0.1",
+    "@deepseek-ai/dsh-tools": "^0.0.1",
+    "cordis": "^4.0.0-rc.6"
+  },
+  "dependencies": {
+    "schemastery": "^3.18.0"
+  },
+  "devDependencies": {
+    "@deepseek-ai/dsh-agent": "^0.0.1",
+    "@deepseek-ai/dsh-llm": "^0.0.1",
+    "@deepseek-ai/dsh-session": "^0.0.1",
+    "@deepseek-ai/dsh-system-prompt": "^0.0.1",
+    "@deepseek-ai/dsh-tools": "^0.0.1",
+    "cordis": "^4.0.0-rc.6"
+  }
+}