feat: add optional llm-task JSON-only tool (#1498)

* feat(llm-task): add optional JSON-only LLM task tool

* fix(llm-task): fix invalid package.json

* fix(llm-task): fix invalid plugin manifest JSON

* fix(llm-task): fix index.ts import quoting

* fix(llm-task): load embedded runner from src or bundled dist

extensions/llm-task/README.md

@@ -0,0 +1,86 @@
+# LLM Task (plugin)
+
+Adds an **optional** agent tool `llm-task` for running **JSON-only** LLM tasks (drafting, summarizing, classifying) with optional JSON Schema validation.
+
+This is designed to be called from workflow engines (e.g. Lobster via `clawd.invoke --each`) without adding new Clawdbot code per workflow.
+
+## Enable
+
+1) Enable the plugin:
+
+```json
+{
+  "plugins": {
+    "entries": {
+      "llm-task": { "enabled": true }
+    }
+  }
+}
+```
+
+2) Allowlist the tool (it is registered with `optional: true`):
+
+```json
+{
+  "agents": {
+    "list": [
+      {
+        "id": "main",
+        "tools": { "allow": ["llm-task"] }
+      }
+    ]
+  }
+}
+```
+
+## Config (optional)
+
+```json
+{
+  "plugins": {
+    "entries": {
+      "llm-task": {
+        "enabled": true,
+        "config": {
+          "defaultProvider": "openai-codex",
+          "defaultModel": "gpt-5.2",
+          "allowedModels": ["openai-codex/gpt-5.2"],
+          "maxTokens": 800,
+          "timeoutMs": 30000
+        }
+      }
+    }
+  }
+}
+```
+
+`allowedModels` is an allowlist of `provider/model` strings. If set, any request outside the list is rejected.
+
+## Tool API
+
+### Parameters
+
+- `prompt` (string, required)
+- `input` (any, optional)
+- `schema` (object, optional JSON Schema)
+- `provider` (string, optional)
+- `model` (string, optional)
+- `authProfileId` (string, optional)
+- `temperature` (number, optional)
+- `maxTokens` (number, optional)
+- `timeoutMs` (number, optional)
+
+### Output
+
+Returns `details.json` containing the parsed JSON (and validates against `schema` when provided).
+
+## Notes
+
+- The tool is **JSON-only** and instructs the model to output only JSON (no code fences, no commentary).
+- Side effects should be handled outside this tool (e.g. approvals in Lobster) before calling tools that send messages/emails.
+
+## Bundled extension note
+
+This extension depends on Clawdbot internal modules (the embedded agent runner). It is intended to ship as a **bundled** Clawdbot extension (like `lobster`) and be enabled via `plugins.entries` + tool allowlists.
+
+It is **not** currently designed to be copied into `~/.clawdbot/extensions` as a standalone plugin directory.