1 files changed, 81 insertions, 0 deletions
diff --git a/agent/tools/write.lua b/agent/tools/write.lua
new file mode 100644
index 0000000..70aa5c8
--- /dev/null
+++ b/agent/tools/write.lua
@@ -0,0 +1,81 @@
+-- Write text to a file, creating parent directories as needed. Pi-style
+-- terse description because every byte of every tool description rides
+-- in the system prompt on every turn.
+
+local uv = require("luv")
+
+-- mkdir -p equivalent: walk the path components and create each.
+-- Ignores EEXIST so the call is idempotent.
+local function mkdir_p(path)
+    if path == "" or path == "." or path == "/" then return true end
+    local parts = {}
+    for piece in string.gmatch(path, "[^/]+") do
+        parts[#parts + 1] = piece
+    end
+    local cur = (path:sub(1, 1) == "/") and "" or "."
+    for _, piece in ipairs(parts) do
+        cur = cur .. "/" .. piece
+        local ok, err, name = uv.fs_mkdir(cur, tonumber("755", 8))
+        if not ok and name ~= "EEXIST" then
+            return nil, err
+        end
+    end
+    return true
+end
+
+-- Return the dirname of `path`, or nil if there isn't one (basename only).
+local function dirname(path)
+    local slash = path:find("/[^/]*$")
+    if not slash or slash == 1 then return nil end
+    return path:sub(1, slash - 1)
+end
+
+return {
+    name = "write",
+    description = "Save content to a path. Overwrites existing files; missing parent directories are created automatically.",
+    schema = {
+        type = "object",
+        properties = {
+            path = { type = "string", description = "Path to the file (relative or absolute)." },
+            content = { type = "string", description = "Exact bytes to write. No newline is added." },
+        },
+        required = { "path", "content" },
+    },
+    handler = function(input)
+        local path = input.path
+        local content = input.content
+
+        if type(path) ~= "string" or path == "" then
+            return "Error: `path` must be a non-empty string."
+        end
+        if type(content) ~= "string" then
+            return "Error: `content` must be a string."
+        end
+
+        local parent = dirname(path)
+        if parent then
+            local ok, err = mkdir_p(parent)
+            if not ok then
+                return "Error: could not create parent directory " .. parent .. ": " .. tostring(err)
+            end
+        end
+
+        local f, open_err = io.open(path, "wb")
+        if not f then
+            return "Error: " .. (open_err or ("could not open " .. path .. " for writing"))
+        end
+
+        local ok, write_err = f:write(content)
+        if not ok then
+            f:close()
+            return "Error: write failed: " .. tostring(write_err)
+        end
+
+        local close_ok, close_err = f:close()
+        if not close_ok then
+            return "Error: close failed: " .. tostring(close_err)
+        end
+
+        return string.format("Wrote %d bytes to %s.", #content, path)
+    end,
+}