toolkit: the tool program, read_file and write_file

Implemented-By: OpenCode session (model recorded in docs/implementer-log.md)

crates/toolkit/src/lib.rs

@@ -1 +1,82 @@
-//! Entry points that run inside tool containers.
+//! The programs that run inside tool containers.
+
+use proto::tools::{ReadFileArgs, WriteFileArgs};
+
+pub mod files;
+pub mod input;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Exit {
+    Done,
+    ToolError,
+    Misuse,
+}
+
+impl Exit {
+    /// 0, 1, 2. No `as` cast: a `match`.
+    pub fn code(self) -> u8 {
+        match self {
+            Exit::Done => 0,
+            Exit::ToolError => 1,
+            Exit::Misuse => 2,
+        }
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct Outcome {
+    pub exit: Exit,
+    pub stdout: String,
+    pub stderr: String,
+}
+
+impl Outcome {
+    pub fn done(stdout: String) -> Outcome {
+        Outcome {
+            exit: Exit::Done,
+            stdout,
+            stderr: String::new(),
+        }
+    }
+
+    pub fn tool_error(stdout: String) -> Outcome {
+        Outcome {
+            exit: Exit::ToolError,
+            stdout,
+            stderr: String::new(),
+        }
+    }
+
+    pub fn misuse(stderr: String) -> Outcome {
+        Outcome {
+            exit: Exit::Misuse,
+            stdout: String::new(),
+            stderr,
+        }
+    }
+}
+
+/// Run tool `name` with the arguments on `stdin`.
+pub fn run(name: &str, stdin: &mut dyn std::io::Read) -> Outcome {
+    let text = match input::read_input(stdin) {
+        Ok(t) => t,
+        Err(e) => return Outcome::misuse(format!("toolkit: {e}")),
+    };
+    match name {
+        "read_file" => {
+            let args = match input::parse::<ReadFileArgs>(name, &text) {
+                Ok(a) => a,
+                Err(e) => return Outcome::misuse(e),
+            };
+            files::read_file(&args)
+        }
+        "write_file" => {
+            let args = match input::parse::<WriteFileArgs>(name, &text) {
+                Ok(a) => a,
+                Err(e) => return Outcome::misuse(e),
+            };
+            files::write_file(&args)
+        }
+        _ => Outcome::misuse(format!("toolkit: unknown tool {name:?}")),
+    }
+}