fmt: applied formatting

Dockerfile

@@ -36,6 +36,21 @@ RUN set -euo pipefail; \
     install -m 0755 "$TMPDIR/usql_static" /usr/local/bin/usql; \
     rm -rf "$TMPDIR"
 
+RUN set -euo pipefail; \
+    DUCKDB_VERSION=1.5.5; \
+    case "${TARGETARCH}" in \
+      amd64) DUCKDB_ARCH=amd64 ;; \
+      arm64) DUCKDB_ARCH=arm64 ;; \
+      *) echo "Unsupported TARGETARCH: ${TARGETARCH}" >&2; exit 1 ;; \
+    esac; \
+    TMPDIR=$(mktemp -d); \
+    curl -fsSL --retry 3 \
+      "https://github.com/duckdb/duckdb/releases/download/v${DUCKDB_VERSION}/duckdb_cli-linux-${DUCKDB_ARCH}.gz" \
+      -o "$TMPDIR/duckdb.gz"; \
+    gunzip "$TMPDIR/duckdb.gz"; \
+    install -m 0755 "$TMPDIR/duckdb" /usr/local/bin/duckdb; \
+    rm -rf "$TMPDIR"
+
 USER 1000
 
 RUN curl -LsSf https://astral.sh/uv/install.sh | sh && \

README.md

@@ -70,6 +70,8 @@ Coyote requires the following tools to be installed on your system:
     * **Cargo:** `cargo install ast-grep --locked`
     * **npm:** `npm i -g @ast-grep/cli`
     * Optional: if `ast-grep` is not installed, the `ast_grep` tool reports it and agents fall back to `fs_grep`
+* [duckdb](https://duckdb.org/) (for fast, local RAGs)
+    * `curl https://install.duckdb.org | sh`
 
 These tools are used to provide various functionalities within Coyote, such as document processing, JSON manipulation,
 etc., and they are used within agents and tools.

src/cli/mod.rs

@@ -13,6 +13,20 @@ use is_terminal::IsTerminal;
 use std::collections::HashSet;
 use std::io::{Read, stdin};
 
+#[derive(clap::ValueEnum, Debug, Clone, Copy, PartialEq, Eq)]
+pub enum McpTransportArg {
+    Stdio,
+    Http,
+    Sse,
+}
+
+#[derive(clap::ValueEnum, Debug, Clone, Copy, PartialEq, Eq, Default)]
+pub enum McpScopeArg {
+    #[default]
+    User,
+    Workspace,
+}
+
 #[derive(Parser, Debug)]
 #[command(author, version, about, long_about = None)]
 #[command(
@@ -41,10 +55,15 @@ use std::io::{Read, stdin};
 				"list_skills", "skill", "tail_logs", "completions", "update",
 			])
 	),
+	group(
+		ArgGroup::new("mcp-action")
+			.args(["mcp_add", "mcp_remove", "mcp_list", "mcp_get"])
+			.multiple(false)
+	),
 )]
 pub struct Cli {
     /// Input text
-    #[arg(trailing_var_arg = true)]
+    #[arg(allow_hyphen_values = true)]
     text: Vec<String>,
 
     /// Select a LLM model
@@ -224,6 +243,57 @@ pub struct Cli {
     #[arg(long, exclusive = true, value_name = "SERVER_NAME", help_heading = "Authentication", add = ArgValueCompleter::new(mcp_server_completer))]
     pub auth_mcp: Option<String>,
 
+    /// Add an MCP server. Use `-- <cmd> [args...]` for stdio, or `--url <URL>` for http/sse.
+    #[arg(long, value_name = "NAME", help_heading = "MCP Servers")]
+    pub mcp_add: Option<String>,
+    /// Remove an MCP server by name
+    #[arg(long, value_name = "NAME", help_heading = "MCP Servers", add = ArgValueCompleter::new(mcp_server_completer))]
+    pub mcp_remove: Option<String>,
+    /// List all configured MCP servers (user + workspace scopes)
+    #[arg(long, help_heading = "MCP Servers")]
+    pub mcp_list: bool,
+    /// Show the JSON config for one MCP server
+    #[arg(long, value_name = "NAME", help_heading = "MCP Servers", add = ArgValueCompleter::new(mcp_server_completer))]
+    pub mcp_get: Option<String>,
+    /// Transport for --mcp-add: stdio (default when `--` present), http, or sse
+    #[arg(
+        long,
+        value_enum,
+        value_name = "TRANSPORT",
+        help_heading = "MCP Servers"
+    )]
+    pub transport: Option<McpTransportArg>,
+    /// URL for http/sse MCP server (used with --mcp-add)
+    #[arg(long, value_name = "URL", help_heading = "MCP Servers")]
+    pub url: Option<String>,
+    /// Scope for MCP config: user (~/.config/coyote/functions/mcp.json) or workspace (./.coyote/mcp.json). Default: user
+    #[arg(long, value_enum, value_name = "SCOPE", help_heading = "MCP Servers")]
+    pub scope: Option<McpScopeArg>,
+    /// Environment variable for stdio MCP server (repeatable): --env KEY=VALUE
+    #[arg(long, value_name = "KEY=VALUE", help_heading = "MCP Servers")]
+    pub env: Vec<String>,
+    /// HTTP header for http/sse MCP server (repeatable): --header "Name: Value"
+    #[arg(long, value_name = "HEADER", help_heading = "MCP Servers")]
+    pub header: Vec<String>,
+    /// Working directory for stdio MCP server
+    #[arg(long, value_name = "PATH", value_hint = ValueHint::AnyPath, help_heading = "MCP Servers")]
+    pub cwd: Option<String>,
+    /// OAuth client ID for http/sse MCP server
+    #[arg(long, value_name = "ID", help_heading = "MCP Servers")]
+    pub client_id: Option<String>,
+    /// OAuth client secret for http/sse MCP server (use {{NAME}} to reference a vault secret)
+    #[arg(long, value_name = "SECRET", help_heading = "MCP Servers")]
+    pub client_secret: Option<String>,
+    /// OAuth callback port for http/sse MCP server
+    #[arg(long, value_name = "PORT", help_heading = "MCP Servers")]
+    pub callback_port: Option<u16>,
+    /// OAuth redirect host for http/sse MCP server
+    #[arg(long, value_name = "HOST", help_heading = "MCP Servers")]
+    pub redirect_host: Option<String>,
+    /// Overwrite an existing MCP server (with --mcp-add) or skip confirmation (with --mcp-remove)
+    #[arg(long, help_heading = "MCP Servers")]
+    pub mcp_force: bool,
+
     /// Launch Coyote inside a Docker sandbox (via `sbx`); name defaults to current directory basename
     #[arg(long, value_name = "NAME", help_heading = "Sandbox")]
     pub sandbox: Option<Option<String>>,
@@ -254,6 +324,15 @@ pub struct Cli {
     /// Generate static shell completion scripts
     #[arg(long, value_name = "SHELL", value_enum, help_heading = "Shell")]
     pub completions: Option<ShellCompletion>,
+
+    /// Stdio command for --mcp-add: everything after `--` is passed to the server verbatim
+    #[arg(
+        last = true,
+        allow_hyphen_values = true,
+        value_name = "CMD",
+        help_heading = "MCP Servers"
+    )]
+    pub mcp_command: Vec<String>,
 }
 
 impl Cli {
@@ -633,4 +712,85 @@ mod tests {
     fn parse_sandbox_is_exclusive() {
         assert!(Cli::try_parse_from(["coyote", "--sandbox", "--agent", "foo"]).is_err());
     }
+
+    #[test]
+    fn parse_mcp_add_stdio_with_trailing_command() {
+        let cli = parse(&[
+            "--mcp-add",
+            "myserver",
+            "--",
+            "npx",
+            "some-server",
+            "--flag",
+            "arg1",
+        ]);
+        assert_eq!(cli.mcp_add, Some("myserver".to_string()));
+        assert_eq!(
+            cli.mcp_command,
+            vec!["npx", "some-server", "--flag", "arg1"]
+        );
+        assert!(cli.text.is_empty());
+    }
+
+    #[test]
+    fn parse_mcp_add_stdio_with_env_and_command() {
+        let cli = parse(&[
+            "--mcp-add",
+            "s",
+            "--env",
+            "API_KEY={{API_KEY}}",
+            "--env",
+            "MODE=dev",
+            "--",
+            "npx",
+            "srv",
+        ]);
+        assert_eq!(cli.mcp_add, Some("s".to_string()));
+        assert_eq!(cli.env, vec!["API_KEY={{API_KEY}}", "MODE=dev"]);
+        assert_eq!(cli.mcp_command, vec!["npx", "srv"]);
+    }
+
+    #[test]
+    fn parse_mcp_add_http_with_header() {
+        let cli = parse(&[
+            "--mcp-add",
+            "notion",
+            "--transport",
+            "http",
+            "--url",
+            "https://mcp.notion.com/mcp",
+            "--header",
+            "Authorization: Bearer {{NOTION_TOKEN}}",
+        ]);
+        assert_eq!(cli.mcp_add, Some("notion".to_string()));
+        assert!(matches!(cli.transport, Some(McpTransportArg::Http)));
+        assert_eq!(cli.url, Some("https://mcp.notion.com/mcp".to_string()));
+        assert_eq!(cli.header, vec!["Authorization: Bearer {{NOTION_TOKEN}}"]);
+        assert!(cli.mcp_command.is_empty());
+    }
+
+    #[test]
+    fn parse_mcp_list_flag() {
+        let cli = parse(&["--mcp-list"]);
+        assert!(cli.mcp_list);
+    }
+
+    #[test]
+    fn parse_mcp_scope_workspace() {
+        let cli = parse(&["--mcp-list", "--scope", "workspace"]);
+        assert!(cli.mcp_list);
+        assert!(matches!(cli.scope, Some(McpScopeArg::Workspace)));
+    }
+
+    #[test]
+    fn parse_mcp_action_group_is_exclusive() {
+        assert!(Cli::try_parse_from(["coyote", "--mcp-list", "--mcp-get", "foo"]).is_err());
+    }
+
+    #[test]
+    fn parse_trailing_text_unchanged_without_dash_dash() {
+        let cli = parse(&["hello", "world"]);
+        assert_eq!(cli.text, vec!["hello", "world"]);
+        assert!(cli.mcp_command.is_empty());
+    }
 }

src/client/claude.rs

@@ -1,3 +1,4 @@
+use std::collections::HashSet;
 use std::mem;
 
 use super::access_token::get_access_token;
@@ -368,17 +369,32 @@ pub fn claude_build_chat_completions_body(
                         ]
                     } else {
                         // One pair per round: Claude can reuse tool_use IDs across API calls.
+                        // A round boundary is detected by the presence of round text, but
+                        // rounds where the model emitted only tool calls (no narration)
+                        // carry no text marker. As a backstop, also split whenever a
+                        // tool_use ID would repeat within the current assistant message —
+                        // the API rejects duplicate tool_use IDs in a single message.
                         let mut messages = vec![];
                         let mut assistant_parts: Vec<serde_json::Value> = vec![];
                         let mut user_parts: Vec<serde_json::Value> = vec![];
+                        let mut chunk_ids: HashSet<&str> = HashSet::new();
                         for (index, tool_result) in tool_results.iter().enumerate() {
-                            if index > 0 && tool_result.text.is_some() {
+                            let id_collision = tool_result
+                                .call
+                                .id
+                                .as_deref()
+                                .is_some_and(|id| chunk_ids.contains(id));
+                            if index > 0 && (tool_result.text.is_some() || id_collision) {
                                 messages.push(
                                     json!({ "role": "assistant", "content": assistant_parts }),
                                 );
                                 messages.push(json!({ "role": "user", "content": user_parts }));
                                 assistant_parts = vec![];
                                 user_parts = vec![];
+                                chunk_ids.clear();
+                            }
+                            if let Some(id) = tool_result.call.id.as_deref() {
+                                chunk_ids.insert(id);
                             }
                             for block in &tool_result.thinking {
                                 assistant_parts.push(json!(block));
@@ -485,10 +501,7 @@ pub fn claude_extract_chat_completions(data: &Value) -> Result<ChatCompletionsOu
                     if let Some(v) = item["thinking"].as_str() {
                         thinking.push(ThinkingBlock::Thinking {
                             thinking: v.to_string(),
-                            signature: item["signature"]
-                                .as_str()
-                                .unwrap_or_default()
-                                .to_string(),
+                            signature: item["signature"].as_str().unwrap_or_default().to_string(),
                         });
                     }
                 }
@@ -535,3 +548,100 @@ pub fn claude_extract_chat_completions(data: &Value) -> Result<ChatCompletionsOu
     };
     Ok(output)
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::function::{ToolCall, ToolResult};
+
+    fn tool_result(id: &str, text: Option<&str>) -> ToolResult {
+        ToolResult {
+            call: ToolCall::new("fs_read".into(), json!({"path": "x"}), Some(id.into())),
+            output: json!("ok"),
+            text: text.map(|t| t.to_string()),
+            thinking: vec![],
+        }
+    }
+
+    fn build_body(tool_results: Vec<ToolResult>) -> Value {
+        let data = ChatCompletionsData {
+            messages: vec![
+                Message::new(MessageRole::User, MessageContent::Text("hello".to_string())),
+                Message::new(
+                    MessageRole::Assistant,
+                    MessageContent::ToolCalls(MessageContentToolCalls {
+                        tool_results,
+                        text: String::new(),
+                        sequence: true,
+                    }),
+                ),
+            ],
+            temperature: None,
+            top_p: None,
+            reasoning_effort: None,
+            functions: None,
+            stream: false,
+        };
+        claude_build_chat_completions_body(data, &Model::new("claude", "claude-test")).unwrap()
+    }
+
+    fn assert_unique_tool_use_ids_per_message(body: &Value) {
+        for message in body["messages"].as_array().unwrap() {
+            let Some(content) = message["content"].as_array() else {
+                continue;
+            };
+            let mut seen = HashSet::new();
+            for block in content {
+                if block["type"] == "tool_use" {
+                    let id = block["id"].as_str().unwrap();
+                    assert!(
+                        seen.insert(id.to_string()),
+                        "duplicate tool_use id `{id}` within a single assistant message: {message}"
+                    );
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn sequence_splits_on_round_text() {
+        let body = build_body(vec![
+            tool_result("toolu_A", None),
+            tool_result("toolu_B", None),
+            tool_result("toolu_C", Some("running another tool")),
+        ]);
+
+        let messages = body["messages"].as_array().unwrap();
+
+        assert_eq!(messages.len(), 5, "body: {body}");
+        assert_unique_tool_use_ids_per_message(&body);
+    }
+
+    #[test]
+    fn sequence_splits_on_reused_id_in_textless_round() {
+        let body = build_body(vec![
+            tool_result("toolu_A", None),
+            tool_result("toolu_B", None),
+            tool_result("toolu_A", None),
+        ]);
+
+        let messages = body["messages"].as_array().unwrap();
+
+        assert_eq!(messages.len(), 5, "body: {body}");
+        assert_unique_tool_use_ids_per_message(&body);
+    }
+
+    #[test]
+    fn sequence_keeps_textless_rounds_merged_when_ids_are_unique() {
+        let body = build_body(vec![
+            tool_result("toolu_A", None),
+            tool_result("toolu_B", None),
+            tool_result("toolu_C", None),
+        ]);
+
+        let messages = body["messages"].as_array().unwrap();
+
+        assert_eq!(messages.len(), 3, "body: {body}");
+        assert_unique_tool_use_ids_per_message(&body);
+    }
+}

src/config/agent.rs

@@ -248,6 +248,10 @@ impl Agent {
             }
         }
 
+        if rag.is_some() && app.function_calling_support && graph_for_rag.is_none() {
+            functions.append_rag_query_functions();
+        }
+
         agent_config.replace_tools_placeholder(&functions);
 
         Ok(Self {

src/config/request_context.rs

@@ -16,8 +16,9 @@ use super::{MessageContentToolCalls, prompts};
 use crate::client::{Model, ModelType, list_models};
 use crate::function::{
     FunctionDeclaration, Functions, ToolCallTracker, ToolResult, memory::MEMORY_FUNCTION_PREFIX,
-    skill::SKILL_FUNCTION_PREFIX, supervisor::SUPERVISOR_FUNCTION_PREFIX,
-    todo::TODO_FUNCTION_PREFIX, user_interaction::USER_FUNCTION_PREFIX,
+    rag_query::RAG_FUNCTION_PREFIX, skill::SKILL_FUNCTION_PREFIX,
+    supervisor::SUPERVISOR_FUNCTION_PREFIX, todo::TODO_FUNCTION_PREFIX,
+    user_interaction::USER_FUNCTION_PREFIX,
 };
 use crate::mcp::{
     MCP_DESCRIBE_META_FUNCTION_NAME_PREFIX, MCP_INVOKE_META_FUNCTION_NAME_PREFIX,
@@ -715,6 +716,7 @@ impl RequestContext {
 
     pub fn exit_rag(&mut self) -> Result<()> {
         self.rag.take();
+        self.tool_scope.functions.remove_rag_query_functions();
         Ok(())
     }
 
@@ -1137,6 +1139,7 @@ impl RequestContext {
                     && !v.name.starts_with("agent__")
                     && !v.name.starts_with("memory__")
                     && !v.name.starts_with("skill__")
+                    && !v.name.starts_with("rag__")
             })
             .map(|v| v.name.clone())
             .collect()
@@ -1957,7 +1960,8 @@ impl RequestContext {
                             || (!matches!(role.skills_enabled(), Some(false))
                                 && v.name.starts_with(SKILL_FUNCTION_PREFIX))
                             || (self.auto_continue_config().enabled
-                                && v.name.starts_with(TODO_FUNCTION_PREFIX)))
+                                && v.name.starts_with(TODO_FUNCTION_PREFIX))
+                            || v.name.starts_with(RAG_FUNCTION_PREFIX))
                             && !existing.contains(&v.name)
                     })
                     .cloned()
@@ -1987,6 +1991,7 @@ impl RequestContext {
                             || v.name.starts_with(TODO_FUNCTION_PREFIX)
                             || v.name.starts_with(SUPERVISOR_FUNCTION_PREFIX)
                             || v.name.starts_with(MEMORY_FUNCTION_PREFIX)
+                            || v.name.starts_with(RAG_FUNCTION_PREFIX)
                     });
                 }
 
@@ -3467,6 +3472,12 @@ impl RequestContext {
         if self.should_register_memory_tools() {
             functions.append_memory_functions();
         }
+        if self.rag.is_some()
+            && app.function_calling_support
+            && !self.agent.as_ref().is_some_and(|a| a.is_graph())
+        {
+            functions.append_rag_query_functions();
+        }
 
         let tool_tracker = self.tool_scope.tool_tracker.clone();
         self.tool_scope = ToolScope {
@@ -4136,7 +4147,7 @@ impl RequestContext {
                             super::TEMP_RAG_NAME,
                             &rag_path,
                             &[],
-                            abort_signal,
+                            abort_signal.clone(),
                             false,
                         )
                         .await?,
@@ -4172,10 +4183,11 @@ impl RequestContext {
         };
         self.rag = Some(rag);
         self.rag_key = rag_key;
+        self.refresh_tool_scope(abort_signal).await?;
         Ok(())
     }
 
-    pub async fn attach_rag(&mut self, name: &str) -> Result<()> {
+    pub async fn attach_rag(&mut self, name: &str, abort_signal: AbortSignal) -> Result<()> {
         let rag_path = self.rag_file(name);
         if rag_path.exists() {
             bail!(
@@ -4192,6 +4204,7 @@ impl RequestContext {
         self.rag_cache().insert(key.clone(), &rag);
         self.rag = Some(rag);
         self.rag_key = Some(key);
+        self.refresh_tool_scope(abort_signal).await?;
         Ok(())
     }
 

src/function/mod.rs

@@ -1,4 +1,5 @@
 pub(crate) mod memory;
+pub(crate) mod rag_query;
 pub(crate) mod skill;
 pub(crate) mod supervisor;
 pub(crate) mod todo;
@@ -23,6 +24,7 @@ use futures_util::future;
 use indexmap::IndexMap;
 use indoc::formatdoc;
 use memory::MEMORY_FUNCTION_PREFIX;
+use rag_query::RAG_FUNCTION_PREFIX;
 use rust_embed::Embed;
 use serde::{Deserialize, Serialize};
 use serde_json::{Value, json};
@@ -495,6 +497,16 @@ impl Functions {
             .extend(user_interaction::user_interaction_function_declarations());
     }
 
+    pub fn append_rag_query_functions(&mut self) {
+        self.declarations
+            .extend(rag_query::rag_query_function_declarations());
+    }
+
+    pub fn remove_rag_query_functions(&mut self) {
+        self.declarations
+            .retain(|f| !f.name.starts_with(RAG_FUNCTION_PREFIX));
+    }
+
     pub fn append_mcp_meta_functions(&mut self, mcp_servers: Vec<String>) {
         let mut invoke_function_properties = IndexMap::new();
         invoke_function_properties.insert(
@@ -1252,6 +1264,15 @@ impl ToolCall {
                         json!({"tool_call_error": error_msg})
                     })
             }
+            _ if cmd_name.starts_with(RAG_FUNCTION_PREFIX) => {
+                rag_query::handle_rag_tool(ctx, &cmd_name, &json_data)
+                    .await
+                    .unwrap_or_else(|e| {
+                        let error_msg = format!("RAG query failed: {e}");
+                        eprintln!("{}", muted_warning_text(&format!("⚠️ {error_msg} ⚠️")));
+                        json!({"tool_call_error": error_msg})
+                    })
+            }
             _ => match run_llm_function(cmd_name, cmd_args, envs, agent_name) {
                 Ok(Some(contents)) => serde_json::from_str(&contents)
                     .ok()

src/function/rag_query.rs

@@ -0,0 +1,101 @@
+use super::{FunctionDeclaration, JsonSchema};
+use crate::config::RequestContext;
+
+use anyhow::{Result, anyhow};
+use indexmap::IndexMap;
+use serde_json::{Value, json};
+
+pub const RAG_FUNCTION_PREFIX: &str = "rag__";
+
+pub fn rag_query_function_declarations() -> Vec<FunctionDeclaration> {
+    vec![FunctionDeclaration {
+        name: format!("{RAG_FUNCTION_PREFIX}query"),
+        description: "Search the RAG knowledge base attached to this session and return \
+                      the most relevant text chunks with their source paths. The relevant \
+                      context has already been injected into the prompt up-front; use this \
+                      tool to pull additional context on-demand when the initial retrieval \
+                      does not fully answer the question. Prefer specific, keyword-rich queries."
+            .to_string(),
+        parameters: JsonSchema {
+            type_value: Some("object".to_string()),
+            properties: Some(IndexMap::from([
+                (
+                    "query".to_string(),
+                    JsonSchema {
+                        type_value: Some("string".to_string()),
+                        description: Some(
+                            "Natural language search query used to retrieve relevant chunks."
+                                .into(),
+                        ),
+                        ..Default::default()
+                    },
+                ),
+                (
+                    "top_k".to_string(),
+                    JsonSchema {
+                        type_value: Some("integer".to_string()),
+                        description: Some(
+                            "Maximum number of chunks to return. Defaults to the RAG's \
+                             configured top_k when omitted."
+                                .into(),
+                        ),
+                        ..Default::default()
+                    },
+                ),
+            ])),
+            required: Some(vec!["query".to_string()]),
+            ..Default::default()
+        },
+        agent: false,
+    }]
+}
+
+pub async fn handle_rag_tool(
+    ctx: &mut RequestContext,
+    cmd_name: &str,
+    args: &Value,
+) -> Result<Value> {
+    let action = cmd_name
+        .strip_prefix(RAG_FUNCTION_PREFIX)
+        .unwrap_or(cmd_name);
+
+    match action {
+        "query" => handle_query(ctx, args).await,
+        _ => Err(anyhow!("Unknown RAG action: {action}")),
+    }
+}
+
+async fn handle_query(ctx: &RequestContext, args: &Value) -> Result<Value> {
+    let rag = ctx
+        .rag
+        .clone()
+        .ok_or_else(|| anyhow!("No RAG is attached to this session"))?;
+
+    let query = args
+        .get("query")
+        .and_then(Value::as_str)
+        .ok_or_else(|| anyhow!("'query' is required"))?;
+
+    let top_k = args
+        .get("top_k")
+        .and_then(Value::as_u64)
+        .map(|v| v as usize)
+        .unwrap_or_else(|| rag.configured_top_k());
+
+    let rerank_model = rag.configured_reranker().map(|s| s.to_string());
+
+    let chunks = rag
+        .search_chunks(query, top_k, rerank_model.as_deref())
+        .await?;
+
+    let chunks_json: Vec<Value> = chunks
+        .into_iter()
+        .map(|(text, source)| json!({ "text": text, "source": source }))
+        .collect();
+
+    Ok(json!({
+        "rag_name": rag.name(),
+        "count": chunks_json.len(),
+        "chunks": chunks_json,
+    }))
+}

src/main.rs

@@ -196,6 +196,18 @@ async fn main() -> Result<()> {
         return Ok(());
     }
 
+    let mcp_action =
+        cli.mcp_list || cli.mcp_get.is_some() || cli.mcp_remove.is_some() || cli.mcp_add.is_some();
+    if mcp_action {
+        let cfg = Config::load_with_interpolation(true).await?;
+        let app_config = AppConfig::from_config(cfg)?;
+        let vault = Vault::init(&app_config)?;
+
+        mcp::manage::handle(&cli, &vault)?;
+
+        return Ok(());
+    }
+
     if vault_flags {
         let cfg = Config::load_with_interpolation(true).await?;
         let app_config = AppConfig::from_config(cfg)?;

src/mcp/manage.rs

@@ -0,0 +1,443 @@
+use crate::cli::{Cli, McpScopeArg, McpTransportArg};
+use crate::config::{ensure_parent_exists, paths};
+use crate::mcp::{JsonField, McpOAuthConfig, McpServer, McpServersConfig, McpTransportType};
+use crate::vault::{SECRET_RE, Vault};
+use anyhow::{Context, Result, anyhow, bail};
+use indexmap::{IndexMap, IndexSet};
+use inquire::Confirm;
+use std::collections::HashSet;
+use std::fs;
+use std::path::{Path, PathBuf};
+
+impl From<McpTransportArg> for McpTransportType {
+    fn from(value: McpTransportArg) -> Self {
+        match value {
+            McpTransportArg::Stdio => McpTransportType::Stdio,
+            McpTransportArg::Http => McpTransportType::Http,
+            McpTransportArg::Sse => McpTransportType::Sse,
+        }
+    }
+}
+
+pub fn handle(cli: &Cli, vault: &Vault) -> Result<()> {
+    if cli.mcp_list {
+        return handle_list(cli.scope);
+    }
+    if let Some(name) = &cli.mcp_get {
+        return handle_get(name, cli.scope);
+    }
+    if let Some(name) = &cli.mcp_remove {
+        return handle_remove(name, cli.scope, cli.mcp_force);
+    }
+    if let Some(name) = &cli.mcp_add {
+        return handle_add(cli, name, vault);
+    }
+
+    Ok(())
+}
+
+fn handle_list(scope: Option<McpScopeArg>) -> Result<()> {
+    let show_user = scope != Some(McpScopeArg::Workspace);
+    let show_workspace = scope != Some(McpScopeArg::User);
+
+    if show_user {
+        let user_path = paths::mcp_config_file();
+        let user_cfg = load_config_raw(&user_path)?;
+        println!("User ({})", user_path.display());
+        print_server_list(&user_cfg);
+    }
+
+    if show_workspace {
+        match paths::workspace_mcp_config_file() {
+            Some(ws_path) => {
+                let ws_cfg = load_config_raw(&ws_path)?;
+                if show_user {
+                    println!();
+                }
+                println!("Workspace ({})", ws_path.display());
+                print_server_list(&ws_cfg);
+            }
+            None if scope == Some(McpScopeArg::Workspace) => {
+                println!("Workspace: no mcp.json found in current directory");
+            }
+            None => {}
+        }
+    }
+
+    Ok(())
+}
+
+fn print_server_list(cfg: &McpServersConfig) {
+    if cfg.mcp_servers.is_empty() {
+        println!("  (none)");
+        return;
+    }
+    let name_width = cfg.mcp_servers.keys().map(String::len).max().unwrap_or(0);
+    for (name, spec) in &cfg.mcp_servers {
+        let transport = match spec.transport_type {
+            McpTransportType::Stdio => "stdio",
+            McpTransportType::Http => "http",
+            McpTransportType::Sse => "sse",
+        };
+        let target = spec.url.clone().unwrap_or_else(|| {
+            let cmd = spec.command.clone().unwrap_or_default();
+            let args = spec.args.as_ref().map(|a| a.join(" ")).unwrap_or_default();
+            if args.is_empty() {
+                cmd
+            } else {
+                format!("{cmd} {args}")
+            }
+        });
+        println!(
+            "  {name:<name_width$}  {transport:<5}  {target}",
+            name_width = name_width
+        );
+    }
+}
+
+fn handle_get(name: &str, scope: Option<McpScopeArg>) -> Result<()> {
+    let (path, cfg) = load_for_scope_or_search(name, scope)?;
+    let spec = cfg
+        .mcp_servers
+        .get(name)
+        .ok_or_else(|| anyhow!("MCP server '{name}' not found"))?;
+    let pretty =
+        serde_json::to_string_pretty(spec).context("failed to serialize MCP server config")?;
+    println!("# {}", path.display());
+    println!("{pretty}");
+
+    Ok(())
+}
+
+fn handle_remove(name: &str, scope: Option<McpScopeArg>, force: bool) -> Result<()> {
+    let (path, mut cfg) = load_for_scope_or_search(name, scope)?;
+    if !force {
+        let ok = Confirm::new(&format!(
+            "Remove MCP server '{name}' from {}?",
+            path.display()
+        ))
+        .with_default(false)
+        .prompt()?;
+
+        if !ok {
+            println!("Aborted.");
+            return Ok(());
+        }
+    }
+
+    cfg.mcp_servers.shift_remove(name);
+    save_config(&path, &cfg)?;
+    println!("✓ Removed MCP server '{name}' from {}", path.display());
+
+    Ok(())
+}
+
+fn handle_add(cli: &Cli, name: &str, vault: &Vault) -> Result<()> {
+    validate_name(name)?;
+    let server = build_server(cli)?;
+    server.validate(name)?;
+
+    let scope = cli.scope.unwrap_or_default();
+    let path = write_path_for_scope(scope);
+    let mut cfg = load_config_raw(&path)?;
+
+    if cfg.mcp_servers.contains_key(name) && !cli.mcp_force {
+        let ok = Confirm::new(&format!(
+            "MCP server '{name}' already exists in {}. Overwrite?",
+            path.display()
+        ))
+        .with_default(false)
+        .prompt()?;
+        if !ok {
+            println!("Aborted. Use --mcp-force to overwrite without prompting.");
+            return Ok(());
+        }
+    }
+
+    provision_secrets(cli, vault)?;
+
+    cfg.mcp_servers.insert(name.to_string(), server);
+    save_config(&path, &cfg)?;
+    println!("✓ Added MCP server '{name}' to {}", path.display());
+
+    Ok(())
+}
+
+fn validate_name(name: &str) -> Result<()> {
+    if name.is_empty() {
+        bail!("MCP server name cannot be empty");
+    }
+
+    if !name
+        .chars()
+        .all(|c| c.is_ascii_alphanumeric() || c == '-' || c == '_')
+    {
+        bail!("Invalid MCP server name '{name}': only letters, digits, '-', and '_' are allowed");
+    }
+
+    Ok(())
+}
+
+fn build_server(cli: &Cli) -> Result<McpServer> {
+    let has_command = !cli.mcp_command.is_empty();
+    let has_url = cli.url.is_some();
+
+    let transport = cli
+        .transport
+        .map(McpTransportType::from)
+        .unwrap_or_else(|| {
+            if has_command {
+                McpTransportType::Stdio
+            } else {
+                McpTransportType::Http
+            }
+        });
+
+    match transport {
+        McpTransportType::Stdio => build_stdio(cli, has_url),
+        McpTransportType::Http | McpTransportType::Sse => build_remote(cli, transport, has_command),
+    }
+}
+
+fn build_stdio(cli: &Cli, has_url: bool) -> Result<McpServer> {
+    if cli.mcp_command.is_empty() {
+        bail!(
+            "stdio MCP server requires a command. Pass it after `--`, e.g. \
+             `--mcp-add NAME -- npx some-server --flag`"
+        );
+    }
+    if has_url {
+        bail!("stdio MCP server does not accept --url");
+    }
+    if !cli.header.is_empty() {
+        bail!("stdio MCP server does not accept --header");
+    }
+    if cli.client_id.is_some()
+        || cli.client_secret.is_some()
+        || cli.callback_port.is_some()
+        || cli.redirect_host.is_some()
+    {
+        bail!("stdio MCP server does not accept OAuth flags");
+    }
+
+    let (cmd, args) = cli.mcp_command.split_first().unwrap();
+
+    let mut env: IndexMap<String, JsonField> = IndexMap::new();
+    for kv in &cli.env {
+        let (k, v) = kv
+            .split_once('=')
+            .ok_or_else(|| anyhow!("invalid --env value '{kv}': expected KEY=VALUE"))?;
+        if k.is_empty() {
+            bail!("invalid --env value '{kv}': KEY cannot be empty");
+        }
+        env.insert(k.to_string(), JsonField::Str(v.to_string()));
+    }
+
+    Ok(McpServer {
+        transport_type: McpTransportType::Stdio,
+        command: Some(cmd.clone()),
+        args: (!args.is_empty()).then(|| args.to_vec()),
+        env: (!env.is_empty()).then_some(env),
+        cwd: cli.cwd.clone(),
+        url: None,
+        headers: None,
+        oauth: None,
+    })
+}
+
+fn build_remote(cli: &Cli, transport: McpTransportType, has_command: bool) -> Result<McpServer> {
+    if has_command {
+        bail!(
+            "http/sse MCP server does not accept a trailing `-- <cmd>`. Use `--url` \
+             to specify the endpoint."
+        );
+    }
+    let url = cli
+        .url
+        .clone()
+        .ok_or_else(|| anyhow!("http/sse MCP server requires --url <URL>"))?;
+    if !cli.env.is_empty() {
+        bail!("http/sse MCP server does not accept --env; use --header instead");
+    }
+    if cli.cwd.is_some() {
+        bail!("http/sse MCP server does not accept --cwd");
+    }
+
+    let mut headers: IndexMap<String, String> = IndexMap::new();
+    for h in &cli.header {
+        let (name, value) = h
+            .split_once(':')
+            .ok_or_else(|| anyhow!("invalid --header value '{h}': expected 'Name: Value'"))?;
+        let name = name.trim();
+        let value = value.trim_start_matches(' ');
+        if name.is_empty() {
+            bail!("invalid --header value '{h}': header name cannot be empty");
+        }
+        headers.insert(name.to_string(), value.to_string());
+    }
+
+    let oauth = if cli.client_id.is_some()
+        || cli.client_secret.is_some()
+        || cli.callback_port.is_some()
+        || cli.redirect_host.is_some()
+    {
+        Some(McpOAuthConfig {
+            client_id: cli.client_id.clone(),
+            client_secret: cli.client_secret.clone(),
+            callback_port: cli.callback_port,
+            redirect_host: cli.redirect_host.clone(),
+        })
+    } else {
+        None
+    };
+
+    Ok(McpServer {
+        transport_type: transport,
+        command: None,
+        args: None,
+        env: None,
+        cwd: None,
+        url: Some(url),
+        headers: (!headers.is_empty()).then_some(headers),
+        oauth,
+    })
+}
+
+fn provision_secrets(cli: &Cli, vault: &Vault) -> Result<()> {
+    let mut sources: Vec<&str> = Vec::new();
+    if let Some(s) = cli.url.as_deref() {
+        sources.push(s);
+    }
+    if let Some(s) = cli.client_secret.as_deref() {
+        sources.push(s);
+    }
+    if let Some(s) = cli.client_id.as_deref() {
+        sources.push(s);
+    }
+    if let Some(s) = cli.redirect_host.as_deref() {
+        sources.push(s);
+    }
+    if let Some(s) = cli.cwd.as_deref() {
+        sources.push(s);
+    }
+    sources.extend(cli.env.iter().map(String::as_str));
+    sources.extend(cli.header.iter().map(String::as_str));
+
+    let mut needed: IndexSet<String> = IndexSet::new();
+    for value in sources {
+        for caps in SECRET_RE.captures_iter(value).filter_map(Result::ok) {
+            if let Some(m) = caps.get(1) {
+                needed.insert(m.as_str().trim().to_string());
+            }
+        }
+    }
+
+    if needed.is_empty() {
+        return Ok(());
+    }
+
+    let existing: HashSet<String> = vault.list_secrets(false)?.into_iter().collect();
+    for name in needed {
+        if existing.contains(&name) {
+            continue;
+        }
+        eprintln!("Value references vault secret {{{{ {name} }}}} which is not stored yet.");
+        let ok = Confirm::new(&format!("Add '{name}' to the vault now?"))
+            .with_default(true)
+            .prompt()?;
+        if !ok {
+            bail!(
+                "Vault secret '{name}' is required by the config; aborting. \
+                 Add it later with `coyote --add-secret {name}`."
+            );
+        }
+        vault.add_secret(&name)?;
+    }
+
+    Ok(())
+}
+
+fn load_for_scope_or_search(
+    name: &str,
+    scope: Option<McpScopeArg>,
+) -> Result<(PathBuf, McpServersConfig)> {
+    if let Some(s) = scope {
+        let path = match s {
+            McpScopeArg::User => paths::mcp_config_file(),
+            McpScopeArg::Workspace => paths::workspace_mcp_config_file()
+                .ok_or_else(|| anyhow!("no workspace mcp.json found in the current directory"))?,
+        };
+        let cfg = load_config_raw(&path)?;
+        if !cfg.mcp_servers.contains_key(name) {
+            bail!(
+                "MCP server '{name}' not found in {} scope ({})",
+                scope_label(s),
+                path.display()
+            );
+        }
+
+        return Ok((path, cfg));
+    }
+
+    let user_path = paths::mcp_config_file();
+    let user_cfg = load_config_raw(&user_path)?;
+    if user_cfg.mcp_servers.contains_key(name) {
+        return Ok((user_path, user_cfg));
+    }
+
+    if let Some(ws_path) = paths::workspace_mcp_config_file() {
+        let ws_cfg = load_config_raw(&ws_path)?;
+        if ws_cfg.mcp_servers.contains_key(name) {
+            return Ok((ws_path, ws_cfg));
+        }
+    }
+
+    bail!("MCP server '{name}' not found in any scope");
+}
+
+fn write_path_for_scope(scope: McpScopeArg) -> PathBuf {
+    match scope {
+        McpScopeArg::User => paths::mcp_config_file(),
+        McpScopeArg::Workspace => paths::workspace_mcp_config_file()
+            .unwrap_or_else(|| paths::workspace_config_dir().join("mcp.json")),
+    }
+}
+
+fn scope_label(scope: McpScopeArg) -> &'static str {
+    match scope {
+        McpScopeArg::User => "user",
+        McpScopeArg::Workspace => "workspace",
+    }
+}
+
+fn load_config_raw(path: &Path) -> Result<McpServersConfig> {
+    if !path.exists() {
+        return Ok(McpServersConfig {
+            mcp_servers: IndexMap::new(),
+        });
+    }
+
+    let raw = fs::read_to_string(path)
+        .with_context(|| format!("failed to read MCP config at {}", path.display()))?;
+    if raw.trim().is_empty() {
+        return Ok(McpServersConfig {
+            mcp_servers: IndexMap::new(),
+        });
+    }
+
+    serde_json::from_str(&raw)
+        .with_context(|| format!("failed to parse MCP config at {}", path.display()))
+}
+
+fn save_config(path: &Path, config: &McpServersConfig) -> Result<()> {
+    ensure_parent_exists(path)?;
+    let serialized =
+        serde_json::to_string_pretty(config).context("failed to serialize MCP config")?;
+    let tmp = path.with_extension("json.tmp");
+    fs::write(&tmp, &serialized)
+        .with_context(|| format!("failed to write temporary MCP config at {}", tmp.display()))?;
+    fs::rename(&tmp, path)
+        .with_context(|| format!("failed to finalize MCP config at {}", path.display()))?;
+
+    Ok(())
+}

src/mcp/mod.rs

@@ -1,3 +1,4 @@
+pub(crate) mod manage;
 pub(crate) mod oauth;
 mod sse_transport;
 
@@ -62,6 +63,8 @@ pub(crate) struct McpServersConfig {
 pub(crate) struct McpOAuthConfig {
     #[serde(rename = "clientId", skip_serializing_if = "Option::is_none")]
     pub client_id: Option<String>,
+    #[serde(rename = "clientSecret", skip_serializing_if = "Option::is_none")]
+    pub client_secret: Option<String>,
     #[serde(rename = "callbackPort", skip_serializing_if = "Option::is_none")]
     pub callback_port: Option<u16>,
     #[serde(rename = "redirectHost", skip_serializing_if = "Option::is_none")]

src/rag/mod.rs

@@ -856,6 +856,20 @@ impl Rag {
         Ok((embeddings, sources, ids))
     }
 
+    pub async fn search_chunks(
+        &self,
+        text: &str,
+        top_k: usize,
+        rerank_model: Option<&str>,
+    ) -> Result<Vec<(String, String)>> {
+        let results = self.hybrid_search(text, top_k, rerank_model).await?;
+
+        Ok(results
+            .into_iter()
+            .map(|(id, content)| (content, self.resolve_source(&id)))
+            .collect())
+    }
+
     pub async fn search_with_template(
         &self,
         app: &AppConfig,

src/repl/mod.rs

@@ -892,7 +892,7 @@ pub async fn run_repl_command(
             ".rag" => match split_first_arg(args) {
                 Some(("attach", rest)) => match rest {
                     Some(name) if !name.trim().is_empty() => {
-                        ctx.attach_rag(name.trim()).await?;
+                        ctx.attach_rag(name.trim(), abort_signal.clone()).await?;
                     }
                     _ => println!("Usage: .rag attach <name>"),
                 },

src/sandbox/mixins.rs

@@ -1,9 +1,10 @@
 use std::env;
 use std::fs;
 use std::fs::{read_dir, read_to_string};
+use std::io;
 use std::path::{Path, PathBuf};
 
-use anyhow::{Context, Result};
+use anyhow::{Context, Result, anyhow, bail};
 use serde_yaml::Value;
 use sha2::{Digest, Sha256};
 
@@ -12,6 +13,7 @@ use crate::config::paths;
 const SBX_MIXIN_FILE_NAME: &str = "sbx-mixin.yaml";
 const SBX_MIXIN_FILE_SUFFIX: &str = ".sbx-mixin.yaml";
 const KIT_SPEC_FILE_NAME: &str = "spec.yaml";
+const MIXIN_FILES_DIR_NAME: &str = "files";
 
 #[derive(Debug, Clone)]
 pub struct DiscoveredMixin {
@@ -34,33 +36,152 @@ impl DiscoveredMixin {
 pub fn wrap_mixin_as_kit(mixin_path: &Path) -> Result<PathBuf> {
     let bytes = fs::read(mixin_path)
         .with_context(|| format!("Failed to read sbx mixin {}", mixin_path.display()))?;
-    wrap_mixin_bytes_as_kit(&bytes, &mixin_path.display().to_string())
+    let label = mixin_path.display().to_string();
+
+    let files = mixin_path
+        .parent()
+        .map(|p| p.join(MIXIN_FILES_DIR_NAME))
+        .filter(|p| p.is_dir())
+        .map(|dir| collect_staged_files(&dir))
+        .transpose()?
+        .unwrap_or_default();
+
+    stage_kit(&bytes, &files, &label)
 }
 
 pub fn wrap_mixin_bytes_as_kit(bytes: &[u8], label: &str) -> Result<PathBuf> {
+    stage_kit(bytes, &[], label)
+}
+
+struct StagedFile {
+    relpath: PathBuf,
+    mode: u32,
+    bytes: Vec<u8>,
+}
+
+fn stage_kit(spec_bytes: &[u8], files: &[StagedFile], label: &str) -> Result<PathBuf> {
     let mut hasher = Sha256::new();
-    hasher.update(bytes);
+    hasher.update(spec_bytes);
+    for f in files {
+        let rel_str = f.relpath.to_str().ok_or_else(|| {
+            anyhow!(
+                "Non-UTF-8 path inside mixin {MIXIN_FILES_DIR_NAME}/: {}",
+                f.relpath.display()
+            )
+        })?;
+        hasher.update(b"\0COYOTE_MIXIN_FILE\0");
+        hasher.update((rel_str.len() as u64).to_le_bytes());
+        hasher.update(rel_str.as_bytes());
+        hasher.update(f.mode.to_le_bytes());
+        hasher.update((f.bytes.len() as u64).to_le_bytes());
+        hasher.update(&f.bytes);
+    }
     let hash = format!("{:x}", hasher.finalize());
 
     let kit_dir = paths::sbx_mixin_kits_dir().join(&hash);
     let spec_path = kit_dir.join(KIT_SPEC_FILE_NAME);
+    let files_dst = kit_dir.join(MIXIN_FILES_DIR_NAME);
 
-    if let Ok(existing) = fs::read(&spec_path)
-        && existing == bytes
-    {
+    let spec_matches = fs::read(&spec_path).is_ok_and(|existing| existing == spec_bytes);
+    let files_ready = files.is_empty() || files_dst.is_dir();
+    if spec_matches && files_ready {
         return Ok(kit_dir);
     }
 
     fs::create_dir_all(&kit_dir)
         .with_context(|| format!("Failed to create mixin kit dir {}", kit_dir.display()))?;
-    fs::write(&spec_path, bytes)
+    fs::write(&spec_path, spec_bytes)
         .with_context(|| format!("Failed to write {}", spec_path.display()))?;
 
+    if !files.is_empty() {
+        if files_dst.exists() {
+            fs::remove_dir_all(&files_dst).with_context(|| {
+                format!(
+                    "Failed to clear stale mixin files at {}",
+                    files_dst.display()
+                )
+            })?;
+        }
+        for f in files {
+            let dst = files_dst.join(&f.relpath);
+            if let Some(parent) = dst.parent() {
+                fs::create_dir_all(parent)
+                    .with_context(|| format!("Failed to create dir {}", parent.display()))?;
+            }
+            fs::write(&dst, &f.bytes)
+                .with_context(|| format!("Failed to write staged mixin file {}", dst.display()))?;
+            #[cfg(unix)]
+            {
+                use std::os::unix::fs::PermissionsExt;
+                fs::set_permissions(&dst, fs::Permissions::from_mode(f.mode))
+                    .with_context(|| format!("Failed to set mode on {}", dst.display()))?;
+            }
+        }
+    }
+
     debug!("Wrapped mixin {label} as kit at {}", kit_dir.display());
 
     Ok(kit_dir)
 }
 
+fn collect_staged_files(root: &Path) -> Result<Vec<StagedFile>> {
+    let mut out = Vec::new();
+    walk_staged_files(root, Path::new(""), &mut out)?;
+    Ok(out)
+}
+
+fn walk_staged_files(abs_dir: &Path, rel_dir: &Path, out: &mut Vec<StagedFile>) -> Result<()> {
+    let rd = fs::read_dir(abs_dir)
+        .with_context(|| format!("Failed to read mixin files dir {}", abs_dir.display()))?;
+    let mut entries: Vec<_> = rd
+        .collect::<io::Result<Vec<_>>>()
+        .with_context(|| format!("Failed to iterate mixin files dir {}", abs_dir.display()))?;
+    entries.sort_by_key(|e| e.file_name());
+
+    for entry in entries {
+        let file_type = entry
+            .file_type()
+            .with_context(|| format!("Failed to stat {}", entry.path().display()))?;
+        let abs = entry.path();
+        let rel = rel_dir.join(entry.file_name());
+
+        if file_type.is_symlink() {
+            bail!(
+                "Symlinks are not allowed inside a mixin {MIXIN_FILES_DIR_NAME}/ tree: {}",
+                abs.display()
+            );
+        }
+
+        if file_type.is_dir() {
+            walk_staged_files(&abs, &rel, out)?;
+        } else if file_type.is_file() {
+            let bytes = fs::read(&abs)
+                .with_context(|| format!("Failed to read staged mixin file {}", abs.display()))?;
+            let mode = staged_file_mode(&entry)?;
+            out.push(StagedFile {
+                relpath: rel,
+                mode,
+                bytes,
+            });
+        }
+    }
+    Ok(())
+}
+
+#[cfg(unix)]
+fn staged_file_mode(entry: &fs::DirEntry) -> Result<u32> {
+    use std::os::unix::fs::PermissionsExt;
+    let meta = entry
+        .metadata()
+        .with_context(|| format!("Failed to stat {}", entry.path().display()))?;
+    Ok(meta.permissions().mode() & 0o777)
+}
+
+#[cfg(not(unix))]
+fn staged_file_mode(_entry: &fs::DirEntry) -> Result<u32> {
+    Ok(0o644)
+}
+
 pub fn discover() -> Result<Vec<DiscoveredMixin>> {
     let mut out = Vec::new();
 
@@ -556,6 +677,196 @@ network:
                 "kit_path should not return the original file path"
             );
         }
+
+        fn write_staged_file(mixin: &Path, rel: &str, content: &[u8]) {
+            let dst = mixin.parent().unwrap().join(MIXIN_FILES_DIR_NAME).join(rel);
+            fs::create_dir_all(dst.parent().unwrap()).unwrap();
+            fs::write(&dst, content).unwrap();
+        }
+
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_copies_sibling_files_tree_into_kit() {
+            let _guard = TestCacheDirGuard::new();
+            let mixin = write_mixin("files-copy", "kind: mixin\nname: probe\n");
+            write_staged_file(&mixin, "home/hello.md", b"# hello\n");
+            write_staged_file(&mixin, "home/nested/deep.txt", b"deep\n");
+
+            let kit_dir = wrap_mixin_as_kit(&mixin).unwrap();
+
+            assert!(kit_dir.join("spec.yaml").exists());
+            let files_root = kit_dir.join(MIXIN_FILES_DIR_NAME);
+            assert!(files_root.is_dir(), "kit dir must contain a files/ tree");
+            assert_eq!(
+                fs::read(files_root.join("home/hello.md")).unwrap(),
+                b"# hello\n"
+            );
+            assert_eq!(
+                fs::read(files_root.join("home/nested/deep.txt")).unwrap(),
+                b"deep\n"
+            );
+        }
+
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_hash_changes_when_a_staged_file_is_edited() {
+            let _guard = TestCacheDirGuard::new();
+            let mixin = write_mixin("files-hash-content", "kind: mixin\nname: probe\n");
+            write_staged_file(&mixin, "home/note.md", b"before\n");
+            let kit_before = wrap_mixin_as_kit(&mixin).unwrap();
+
+            write_staged_file(&mixin, "home/note.md", b"after\n");
+            let kit_after = wrap_mixin_as_kit(&mixin).unwrap();
+
+            assert_ne!(
+                kit_before, kit_after,
+                "editing a staged file must invalidate the kit hash"
+            );
+            assert_eq!(
+                fs::read(kit_after.join("files/home/note.md")).unwrap(),
+                b"after\n"
+            );
+        }
+
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_hash_changes_when_a_staged_file_is_added() {
+            let _guard = TestCacheDirGuard::new();
+            let mixin = write_mixin("files-hash-added", "kind: mixin\nname: probe\n");
+            write_staged_file(&mixin, "home/one.md", b"one\n");
+            let kit_before = wrap_mixin_as_kit(&mixin).unwrap();
+
+            write_staged_file(&mixin, "home/two.md", b"two\n");
+            let kit_after = wrap_mixin_as_kit(&mixin).unwrap();
+
+            assert_ne!(
+                kit_before, kit_after,
+                "adding a staged file must invalidate the kit hash"
+            );
+        }
+
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_hash_unchanged_when_no_files_dir() {
+            let _guard = TestCacheDirGuard::new();
+            let content = "kind: mixin\nname: legacy\n";
+            let mixin = write_mixin("legacy-no-files", content);
+
+            let with_helper = wrap_mixin_as_kit(&mixin).unwrap();
+            let bytes_only = wrap_mixin_bytes_as_kit(content.as_bytes(), "legacy").unwrap();
+
+            assert_eq!(
+                with_helper, bytes_only,
+                "mixins without a sibling files/ must keep the legacy bytes-only hash to reuse existing cache dirs"
+            );
+        }
+
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_ignores_sibling_files_that_is_not_a_directory() {
+            let _guard = TestCacheDirGuard::new();
+            let content = "kind: mixin\nname: probe\n";
+            let mixin = write_mixin("files-not-a-dir", content);
+            fs::write(mixin.parent().unwrap().join(MIXIN_FILES_DIR_NAME), b"decoy").unwrap();
+
+            let wrapped = wrap_mixin_as_kit(&mixin).unwrap();
+            let bytes_only = wrap_mixin_bytes_as_kit(content.as_bytes(), "probe").unwrap();
+
+            assert_eq!(
+                wrapped, bytes_only,
+                "a regular file named files must be ignored, not staged"
+            );
+            assert!(!wrapped.join(MIXIN_FILES_DIR_NAME).exists());
+        }
+
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_rebuilds_files_when_cache_dir_missing_files_tree() {
+            let _guard = TestCacheDirGuard::new();
+            let mixin = write_mixin("files-rebuild", "kind: mixin\nname: probe\n");
+            write_staged_file(&mixin, "home/hello.md", b"hi\n");
+
+            let kit_dir = wrap_mixin_as_kit(&mixin).unwrap();
+            let files_dst = kit_dir.join(MIXIN_FILES_DIR_NAME);
+            fs::remove_dir_all(&files_dst).unwrap();
+            assert!(!files_dst.exists());
+
+            let kit_again = wrap_mixin_as_kit(&mixin).unwrap();
+
+            assert_eq!(kit_again, kit_dir, "kit path is content-addressed");
+            assert!(
+                files_dst.is_dir(),
+                "a partial cache (spec present, files/ missing) must be rebuilt"
+            );
+            assert_eq!(fs::read(files_dst.join("home/hello.md")).unwrap(), b"hi\n");
+        }
+
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_deterministic_with_staged_files() {
+            let _guard = TestCacheDirGuard::new();
+            let content = "kind: mixin\nname: probe\n";
+            let mixin_one = write_mixin("determ-1", content);
+            write_staged_file(&mixin_one, "home/note.md", b"same\n");
+            let mixin_two = write_mixin("determ-2", content);
+            write_staged_file(&mixin_two, "home/note.md", b"same\n");
+
+            let kit_a = wrap_mixin_as_kit(&mixin_one).unwrap();
+            let kit_b = wrap_mixin_as_kit(&mixin_two).unwrap();
+
+            assert_eq!(
+                kit_a, kit_b,
+                "identical spec+files must produce the same content-addressed kit dir"
+            );
+        }
+
+        #[cfg(unix)]
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_rejects_symlinks_inside_files_tree() {
+            use std::os::unix::fs::symlink;
+
+            let _guard = TestCacheDirGuard::new();
+            let mixin = write_mixin("files-symlink", "kind: mixin\nname: probe\n");
+            let files_dir = mixin.parent().unwrap().join(MIXIN_FILES_DIR_NAME);
+            fs::create_dir_all(&files_dir).unwrap();
+            let target = files_dir.join("target.txt");
+            fs::write(&target, b"real").unwrap();
+            symlink(&target, files_dir.join("link.txt")).unwrap();
+
+            let err = wrap_mixin_as_kit(&mixin).unwrap_err();
+            let msg = format!("{err:#}");
+            assert!(
+                msg.contains("Symlinks are not allowed"),
+                "expected symlink rejection, got: {msg}"
+            );
+        }
+
+        #[cfg(unix)]
+        #[test]
+        #[serial]
+        fn wrap_mixin_as_kit_preserves_executable_bit() {
+            use std::os::unix::fs::PermissionsExt;
+
+            let _guard = TestCacheDirGuard::new();
+            let mixin = write_mixin("files-exec", "kind: mixin\nname: probe\n");
+            write_staged_file(&mixin, "bin/run.sh", b"#!/bin/sh\necho hi\n");
+            let src = mixin
+                .parent()
+                .unwrap()
+                .join(MIXIN_FILES_DIR_NAME)
+                .join("bin/run.sh");
+            fs::set_permissions(&src, fs::Permissions::from_mode(0o755)).unwrap();
+
+            let kit_dir = wrap_mixin_as_kit(&mixin).unwrap();
+            let dst = kit_dir.join("files/bin/run.sh");
+            let mode = fs::metadata(&dst).unwrap().permissions().mode() & 0o777;
+
+            assert_eq!(
+                mode, 0o755,
+                "executable bit must survive the copy into the kit dir"
+            );
+        }
     }
 
     #[test]