Harness spec 1.1.0: one plan, prototypes and the library shared; the CLI implements it

The spec: plan_write and plan_update (new, shared, offered in every mode) and
plan_submit (now shared) keep one structured plan — findings, objectives,
phases of tasks — in place of the todo list, which lives on as a former name
of plan_write. The shared system text is one text for both projects, with
variables for what differs; the mode texts, a prototypes block and a library
block are shared. acp.md: the client hands the device what only it knows
(context, library, prototypes), the plan travels as a structure (plan_state),
library calls carry the chat's scope, and a client may rewind a session.
loop.json says its numbers as numbers. Four conformance areas: plan,
prototype, library_scope, toolcall_index.

The CLI: the plan is kept per session in the store and drawn above the prompt
and on the approval card; the prompt is assembled from the spec's texts with
their variables filled; the link reads the instance's instructions,
personalization, knowledge scope and prototype offer, sends the plan as a
structure and answers rewind; library calls to the instance carry the session
as scope; a prototype written in the terminal is saved as a file and named in
the transcript; a tool-call fragment without an index continues the last call;
the default theme is Moria; dead exports and Hermes leftovers removed.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

harness/tools/plan_update.json

@@ -0,0 +1,131 @@
+{
+  "name": "plan_update",
+  "scope": "shared",
+  "risk": "interact",
+  "exclusive": false,
+  "block": "plan",
+  "purpose": false,
+  "aliases": {
+    "cli": [],
+    "llembas": []
+  },
+  "description": "Change the plan as the work goes: mark a task doing when you start it and done once you have checked it works, drop one that turned out unnecessary (say why in its note), add work the plan did not anticipate, record a new finding. Several changes go in one call. Quote the ids the plan shows (p1, t3, o2); an unknown id is an error naming the known ones. Updating is bookkeeping, not a milestone: carry straight on afterwards.",
+  "parameters": {
+    "type": "object",
+    "properties": {
+      "tasks": {
+        "type": "array",
+        "description": "Tasks to change, by id",
+        "items": {
+          "type": "object",
+          "properties": {
+            "id": {
+              "type": "string",
+              "minLength": 1
+            },
+            "status": {
+              "type": "string",
+              "enum": [
+                "todo",
+                "doing",
+                "done",
+                "dropped"
+              ]
+            },
+            "note": {
+              "type": "string",
+              "maxLength": 300
+            }
+          },
+          "required": [
+            "id"
+          ]
+        }
+      },
+      "objectives": {
+        "type": "array",
+        "description": "Objectives to change, by id",
+        "items": {
+          "type": "object",
+          "properties": {
+            "id": {
+              "type": "string",
+              "minLength": 1
+            },
+            "status": {
+              "type": "string",
+              "enum": [
+                "open",
+                "done",
+                "dropped"
+              ]
+            }
+          },
+          "required": [
+            "id",
+            "status"
+          ]
+        }
+      },
+      "phases": {
+        "type": "array",
+        "description": "Phases to change, by id",
+        "items": {
+          "type": "object",
+          "properties": {
+            "id": {
+              "type": "string",
+              "minLength": 1
+            },
+            "status": {
+              "type": "string",
+              "enum": [
+                "pending",
+                "active",
+                "done"
+              ]
+            }
+          },
+          "required": [
+            "id",
+            "status"
+          ]
+        }
+      },
+      "add_tasks": {
+        "type": "array",
+        "description": "New tasks, each in a phase; after an existing task's id, or at the end of the phase",
+        "items": {
+          "type": "object",
+          "properties": {
+            "phase": {
+              "type": "string",
+              "minLength": 1
+            },
+            "text": {
+              "type": "string",
+              "minLength": 1,
+              "maxLength": 300
+            },
+            "after": {
+              "type": "string"
+            }
+          },
+          "required": [
+            "phase",
+            "text"
+          ]
+        }
+      },
+      "add_findings": {
+        "type": "array",
+        "description": "New findings",
+        "items": {
+          "type": "string",
+          "minLength": 1,
+          "maxLength": 300
+        }
+      }
+    }
+  }
+}