fix(FN-2392): normalize skill-facing tool references to fn_*

- Update Fusion skill docs, prompts, and capability references to use public fn_* tool names consistently
- Align engine system prompts and tool schemas for messaging/task actions with fn_send_message, fn_read_messages, fn_task_* naming
- Refresh related tests across CLI, engine, dashboard, and core to match normalized tool naming and behavior
- Add a patch changeset for @runfusion/fusion describing the skill-tool namespace normalization

packages/cli/skill/fusion/SKILL.md

@@ -21,6 +21,8 @@ Mission → Milestone → Slice → Feature → Task
 
 **Available tools:** Fusion registers tools via the pi extension (prefixed `fn_*`). No CLI commands or Bash needed — use the registered tools directly.
 
+**Naming boundary:** The published skill surface always uses `fn_*` tool names (for example `fn_task_create`, `fn_mission_create`). Internal engine runtime tools like `task_create`, `task_update`, `task_log`, and `task_done` are intentionally unprefixed and not part of this skill.
+
 **Tool categories:**
 - **Task tools** — `fn_task_create`, `fn_task_update`, `fn_task_list`, `fn_task_show`, `fn_task_attach`, `fn_task_pause`, `fn_task_unpause`, `fn_task_retry`, `fn_task_duplicate`, `fn_task_refine`, `fn_task_archive`, `fn_task_unarchive`, `fn_task_delete`, `fn_task_plan`
 - **GitHub tools** — `fn_task_import_github`, `fn_task_import_github_issue`, `fn_task_browse_github_issues`

packages/cli/skill/fusion/references/extension-tools.md

@@ -2,6 +2,8 @@
 
 All tools are registered via the pi extension. They are available in any pi agent session when the Fusion extension is installed.
 
+> Naming contract: all externally exposed Fusion extension tools are `fn_*` (for example `fn_task_create`). Internal engine/executor runtime tools (`task_create`, `task_update`, `task_log`, `task_done`, etc.) are separate and intentionally out of scope for this skill surface.
+
 ## Task Tools
 
 ### fn_task_create

packages/cli/skill/fusion/references/fusion-capabilities.md

@@ -7,6 +7,8 @@ Triage → Todo → In Progress → In Review → Done → Archived
 
 ## Pi Extension Tools (Available to Agents)
 
+All skill/extension tool invocations in this catalog use the public `fn_*` namespace. Engine runtime tools (for example `task_create`, `task_update`, `task_log`, `task_done`) are internal and intentionally not listed here.
+
 | Tool | Purpose |
 |------|---------|
 | `fn_task_create` | Create a new task in triage |

packages/cli/skill/fusion/workflows/specifications.md

@@ -5,6 +5,8 @@
 
 <objective>
 Guide the agent through creating well-specified tasks and organizing work using the mission hierarchy for complex multi-phase projects.
+
+All tool examples in this workflow intentionally use the public `fn_*` extension namespace.
 </objective>
 
 <process>

packages/cli/skill/fusion/workflows/task-management.md

@@ -5,6 +5,8 @@
 
 <objective>
 Guide the agent through creating, viewing, and managing tasks on the Fusion board using pi extension tools.
+
+Use only the public `fn_*` extension tools in this workflow. Do not substitute internal engine runtime tools like `task_create`, `task_update`, `task_log`, or `task_done`.
 </objective>
 
 <process>