image uploads

1 files changed, 54 insertions, 0 deletions

diff --git a/agent/tools/read.lua b/agent/tools/read.lua
index f232890..ab92c05 100644
--- a/agent/tools/read.lua
+++ b/agent/tools/read.lua
@@ -15,6 +15,30 @@
 
 local uv = require("luv")
 
+-- Minimal magic-byte sniff: binary attachment (image/PDF) vs. text.
+-- We only decide *whether* the bytes are an attachment; libpanto does the
+-- precise type detection, resizing, and encoding from the raw bytes. Keep
+-- this in lockstep with `libpanto/src/image.zig`'s `detectCodec`.
+local function is_attachment(head)
+    local b = { head:byte(1, 12) }
+    -- PNG: 89 50 4E 47 0D 0A 1A 0A
+    if b[1] == 0x89 and b[2] == 0x50 and b[3] == 0x4E and b[4] == 0x47
+        and b[5] == 0x0D and b[6] == 0x0A and b[7] == 0x1A and b[8] == 0x0A then
+        return true
+    end
+    -- JPEG: FF D8 FF
+    if b[1] == 0xFF and b[2] == 0xD8 and b[3] == 0xFF then return true end
+    -- GIF: "GIF87a" / "GIF89a"
+    if head:sub(1, 6) == "GIF87a" or head:sub(1, 6) == "GIF89a" then return true end
+    -- BMP: "BM"
+    if b[1] == 0x42 and b[2] == 0x4D then return true end
+    -- WEBP: "RIFF"????"WEBP"
+    if head:sub(1, 4) == "RIFF" and head:sub(9, 12) == "WEBP" then return true end
+    -- PDF: "%PDF-"
+    if head:sub(1, 5) == "%PDF-" then return true end
+    return false
+end
+
 local MAX_BYTES = 50 * 1024   -- 50 KB
 local MAX_LINES = 2000
 local READ_CHUNK_SIZE = MAX_BYTES
@@ -229,6 +253,36 @@ return {
             return "Error: " .. (open_err or ("could not open " .. path))
         end
 
+        -- Binary attachment path. We do the *minimal* magic-byte sniff
+        -- here — only enough to decide "binary attachment vs. text". If
+        -- it's an attachment, we return the raw file bytes; libpanto does
+        -- the real work (precise type detection, resizing, encoding).
+        do
+            local herr, header = fs_read(fd, 16, 0)
+            if not herr and header and #header > 0 and is_attachment(header) then
+                local whole, rerr = (function()
+                    local chunks = {}
+                    local off = 0
+                    while true do
+                        local e, d = fs_read(fd, READ_CHUNK_SIZE, off)
+                        if e then return nil, e end
+                        if d == nil or #d == 0 then break end
+                        chunks[#chunks + 1] = d
+                        off = off + #d
+                    end
+                    return table.concat(chunks)
+                end)()
+                fs_close(fd)
+                if not whole then
+                    return "Error: read failed: " .. tostring(rerr)
+                end
+                return {
+                    text = string.format("[read %s as binary attachment]", path),
+                    attachments = { { data = whole } },
+                }
+            end
+        end
+
         local parts = {}
         local emitted_lines = 0
         local emitted_bytes = 0