docs(rfd): Add RFD 094 for built-in tell_user tool

docs/.vitepress/rfd-summaries.json

@@ -224,7 +224,7 @@
     "summary": "Adds group `overrides` section to enforce tool configuration that outlasts tool-level settings but yields to CLI flags."
   },
   "058-typed-content-blocks-for-tool-responses.md": {
-    "hash": "4c8b925d579414f5ffa5d8f45d6a3a9628651d690cc01e017c3e129f369398cc",
+    "hash": "5e603eb54c4ddd915729fc1e2e99a3b5e9bd955e0babe11883656198a5bcf2e2",
     "summary": "Replace opaque tool output strings with typed content blocks (text, resource, question) mirroring MCP's CallToolResult model."
   },
   "059-shell-completions-and-man-pages.md": {
@@ -370,5 +370,9 @@
   "093-inline-first-query-composition.md": {
     "hash": "a4fa8987e41f656a337952452629eafd5768c9c24ffdbe30556692f0ffb616cb",
     "summary": "Bare `jp query` composes inline by default; `Ctrl+X` escapes to external editor, with fallback modes configurable via `query.compose_in_editor`."
+  },
+  "094-built-in-tell_user-tool-for-mid-turn-user-addressed-messages.md": {
+    "hash": "ffca3c7ad1fdbeb597df5b4ac2e3ad2dd85f944b390194ade88040755af1d2da",
+    "summary": "Add a built-in tell_user tool letting assistants deliver mid-turn user messages without ending the agentic loop."
   }
 }

docs/rfd/058-typed-content-blocks-for-tool-responses.md

@@ -6,6 +6,7 @@
 - **Date**: 2026-03-15
 - **Requires**: [RFD 009], [RFD 065]
 - **Required by**: [RFD 066], [RFD 067]
+- **Extended by**: [RFD 094]
 
 ## Summary
 
@@ -139,6 +140,42 @@ The tool owns the formatting.
 }
 ```
 
+Text blocks may carry an optional `mimeType` describing the format of the text:
+
+```json
+{
+  "type": "text",
+  "text": "## Summary\n\nAll checks passed.",
+  "mimeType": "text/markdown"
+}
+```
+
+This is a JP extension — MCP's `TextContent` has no mimeType — following the
+MCP-compatible superset principle from [RFD 065].
+MCP tools never set it, and absence means plain text.
+LLM delivery is unchanged either way: the text passes through as-is.
+The field exists to inform JP-side presentation of the block; as with
+annotations, JP defines it for type-level use but does not act on it initially.
+
+Text blocks also support MCP's standard annotations (`audience`, `priority`,
+`lastModified`), matching MCP's `TextContent` schema — MCP defines annotations
+on every content type, not only resources:
+
+```json
+{
+  "type": "text",
+  "text": "Summary for the user.",
+  "annotations": {
+    "audience": [
+      "user"
+    ]
+  }
+}
+```
+
+As with resource blocks, JP defines the annotation types for type-level
+compatibility but does not act on them initially.
+
 #### `resource`
 
 Identified content with a URI and mimeType.
@@ -494,6 +531,13 @@ JP's internal type for tool results, defined in `jp_tool`:
 pub enum ContentBlock {
     Text {
         text: String,
+        /// Optional MIME type describing the text format (JP extension; MCP
+        /// tools never set it).
+        /// Absent means plain text.
+        mime_type: Option<String>,
+        /// MCP-standard annotations (`audience`, `priority`, `lastModified`).
+        /// Carried for MCP compatibility; not acted on initially.
+        annotations: Option<Annotations>,
     },
     Resource(Resource),
     Question {
@@ -505,8 +549,9 @@ pub enum ContentBlock {
 pub struct InputRequest {
     /// Unique ID for correlating answers on re-execution.
     pub id: String,
-    /// Short prompt label (one-liner). Displayed alongside the input field
-    /// in the terminal, or as the question text sent to the assistant.
+    /// Short prompt label (one-liner).
+    /// Displayed alongside the input field in the terminal, or as the question
+    /// text sent to the assistant.
     /// Supporting context belongs in content blocks, not here.
     pub text: String,
     /// JSON Schema defining the expected answer shape.
@@ -545,6 +590,10 @@ converts it to a single `ContentBlock::Text` block.
 On serialization, the new format is written.
 Old conversations remain readable; re-saved conversations use the new format.
 
+The migration carries JP's own consumers of the serialized shape with it: the
+terminal result renderer and the serve-web plugin become block-aware, and
+`inline_results` applies uniformly to a response's blocks.
+
 ### Response parsing
 
 `parse_command_output` in `jp_llm/src/tool.rs` is the single parsing point for
@@ -830,3 +879,4 @@ Depends on Phase 5.
 [RFD 065]: 065-typed-resource-model-for-attachments.md
 [RFD 066]: 066-content-addressable-blob-store.md
 [RFD 067]: 067-resource-deduplication-for-token-efficiency.md
+[RFD 094]: 094-built-in-tell_user-tool-for-mid-turn-user-addressed-messages.md