1 files changed, 195 insertions, 0 deletions
diff --git a/crates/phone-opus/src/mcp/output.rs b/crates/phone-opus/src/mcp/output.rs
new file mode 100644
index 0000000..90673b3
--- /dev/null
+++ b/crates/phone-opus/src/mcp/output.rs
@@ -0,0 +1,195 @@
+use libmcp::{
+    DetailLevel, FallbackJsonProjection, JsonPorcelainConfig, ProjectionError, RenderMode,
+    SurfaceKind, ToolProjection, render_json_porcelain, with_presentation_properties,
+};
+use serde::Serialize;
+use serde_json::{Value, json};
+
+use crate::mcp::fault::{FaultRecord, FaultStage};
+
+const FULL_PORCELAIN_MAX_LINES: usize = 40;
+const FULL_PORCELAIN_MAX_INLINE_CHARS: usize = 512;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub(crate) struct Presentation {
+    pub(crate) render: RenderMode,
+    pub(crate) detail: DetailLevel,
+}
+
+#[derive(Debug, Clone)]
+pub(crate) struct ToolOutput {
+    concise: Value,
+    full: Value,
+    concise_text: String,
+    full_text: Option<String>,
+}
+
+impl ToolOutput {
+    pub(crate) fn from_values(
+        concise: Value,
+        full: Value,
+        concise_text: impl Into<String>,
+        full_text: Option<String>,
+    ) -> Self {
+        Self {
+            concise,
+            full,
+            concise_text: concise_text.into(),
+            full_text,
+        }
+    }
+
+    fn structured(&self, detail: DetailLevel) -> &Value {
+        match detail {
+            DetailLevel::Concise => &self.concise,
+            DetailLevel::Full => &self.full,
+        }
+    }
+
+    fn porcelain_text(&self, detail: DetailLevel) -> String {
+        match detail {
+            DetailLevel::Concise => self.concise_text.clone(),
+            DetailLevel::Full => self
+                .full_text
+                .clone()
+                .unwrap_or_else(|| render_json_porcelain(&self.full, full_porcelain_config())),
+        }
+    }
+}
+
+impl Default for Presentation {
+    fn default() -> Self {
+        Self {
+            render: RenderMode::Porcelain,
+            detail: DetailLevel::Concise,
+        }
+    }
+}
+
+pub(crate) fn split_presentation(
+    arguments: Value,
+    operation: &str,
+    generation: libmcp::Generation,
+    stage: FaultStage,
+) -> Result<(Presentation, Value), FaultRecord> {
+    let Value::Object(mut object) = arguments else {
+        return Ok((Presentation::default(), arguments));
+    };
+    let render = object
+        .remove("render")
+        .map(|value| {
+            serde_json::from_value::<RenderMode>(value).map_err(|error| {
+                FaultRecord::invalid_input(
+                    generation,
+                    stage,
+                    operation,
+                    format!("invalid render mode: {error}"),
+                )
+            })
+        })
+        .transpose()?
+        .unwrap_or(RenderMode::Porcelain);
+    let detail = object
+        .remove("detail")
+        .map(|value| {
+            serde_json::from_value::<DetailLevel>(value).map_err(|error| {
+                FaultRecord::invalid_input(
+                    generation,
+                    stage,
+                    operation,
+                    format!("invalid detail level: {error}"),
+                )
+            })
+        })
+        .transpose()?
+        .unwrap_or(DetailLevel::Concise);
+    Ok((Presentation { render, detail }, Value::Object(object)))
+}
+
+pub(crate) fn projected_tool_output(
+    projection: &impl ToolProjection,
+    concise_text: impl Into<String>,
+    full_text: Option<String>,
+    generation: libmcp::Generation,
+    stage: FaultStage,
+    operation: &str,
+) -> Result<ToolOutput, FaultRecord> {
+    let concise = projection
+        .concise_projection()
+        .map_err(|error| projection_fault(error, generation, stage, operation))?;
+    let full = projection
+        .full_projection()
+        .map_err(|error| projection_fault(error, generation, stage, operation))?;
+    Ok(ToolOutput::from_values(
+        concise,
+        full,
+        concise_text,
+        full_text,
+    ))
+}
+
+pub(crate) fn fallback_detailed_tool_output(
+    concise: &impl Serialize,
+    full: &impl Serialize,
+    concise_text: impl Into<String>,
+    full_text: Option<String>,
+    kind: SurfaceKind,
+    generation: libmcp::Generation,
+    stage: FaultStage,
+    operation: &str,
+) -> Result<ToolOutput, FaultRecord> {
+    let projection = FallbackJsonProjection::new(concise, full, kind)
+        .map_err(|error| projection_fault(error, generation, stage, operation))?;
+    projected_tool_output(
+        &projection,
+        concise_text,
+        full_text,
+        generation,
+        stage,
+        operation,
+    )
+}
+
+pub(crate) fn tool_success(
+    output: ToolOutput,
+    presentation: Presentation,
+    generation: libmcp::Generation,
+    stage: FaultStage,
+    operation: &str,
+) -> Result<Value, FaultRecord> {
+    let structured = output.structured(presentation.detail).clone();
+    let text = match presentation.render {
+        RenderMode::Porcelain => output.porcelain_text(presentation.detail),
+        RenderMode::Json => serde_json::to_string_pretty(&structured).map_err(|error| {
+            FaultRecord::internal(generation, stage, operation, error.to_string())
+        })?,
+    };
+    Ok(json!({
+        "content": [{
+            "type": "text",
+            "text": text,
+        }],
+        "structuredContent": structured,
+        "isError": false,
+    }))
+}
+
+pub(crate) fn with_common_presentation(schema: Value) -> Value {
+    with_presentation_properties(schema)
+}
+
+fn projection_fault(
+    error: ProjectionError,
+    generation: libmcp::Generation,
+    stage: FaultStage,
+    operation: &str,
+) -> FaultRecord {
+    FaultRecord::internal(generation, stage, operation, error.to_string())
+}
+
+const fn full_porcelain_config() -> JsonPorcelainConfig {
+    JsonPorcelainConfig {
+        max_lines: FULL_PORCELAIN_MAX_LINES,
+        max_inline_chars: FULL_PORCELAIN_MAX_INLINE_CHARS,
+    }
+}