Harness spec 3.0.0-draft: where each tool is offered; the chat's tools

Every tool says its `sessions` (chat, agent or both). The file tools read, write,
edit, glob, grep and list are shared; mkdir, mv, rm, search, python and the forge
verbs (commit, branch, pr, merge, tag, release) are the chat's; show and recall
are new and shared. New fields: `requires` (page, display, forge) with the exact
`unavailable` answer, and `confirm: always` for merge, tag and release.
knowledge_*, notes_search, note_view and note_manage leave the chat. Default
rules for the new tools; modes.json says what `confirm` does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

harness/tools/python.json

@@ -0,0 +1,50 @@
+{
+  "name": "python",
+  "scope": "llembas",
+  "sessions": "chat",
+  "risk": "execute",
+  "exclusive": false,
+  "block": "shell",
+  "purpose": "purpose",
+  "requires": [
+    "page"
+  ],
+  "unavailable": "Python cannot run now: no open browser page is attached to this chat.",
+  "aliases": {
+    "cli": [],
+    "llembas": []
+  },
+  "variables": {
+    "packages": "the packages the instance provides beyond the standard library, as a list, or \"none\"",
+    "seconds": "the time limit of one call, in seconds",
+    "memory": "the memory limit of one call, with its unit",
+    "output": "how much printed output comes back, with its unit"
+  },
+  "description": "Run Python for calculations and for working with files — parse JSON or CSV, transform text, compute. It runs in the user's browser (Pyodide), sandboxed: no network, no shell, no packages beyond the standard library and these: {{packages}}. Returns what the code printed and the value of its last expression.\n\n- `files` are copied in before the run, at the same paths, from what this session can read.\n- Files the code writes come back only when listed in `save`: each is written as the write tool would write it, with this session's permissions.\n- At most {{seconds}} seconds and {{memory}} of memory per call; printed output past {{output}} is cut.\n- Every call starts fresh: nothing is kept between calls.",
+  "parameters": {
+    "type": "object",
+    "properties": {
+      "code": {
+        "type": "string",
+        "description": "The Python code to run"
+      },
+      "files": {
+        "type": "array",
+        "items": {
+          "type": "string"
+        },
+        "description": "Files to copy in before the run"
+      },
+      "save": {
+        "type": "array",
+        "items": {
+          "type": "string"
+        },
+        "description": "Files the code writes that are to be saved back"
+      }
+    },
+    "required": [
+      "code"
+    ]
+  }
+}