📝 CodeRabbit Chat: Implement requested code changes

lua/qjson/table.lua

@@ -344,21 +344,18 @@ LazyObject.__newindex = function(t, k, v)
             end
         end
     else
-        -- Encode the new value (we need both encoded and lua_value)
-        local encoded = encode(v)
-
-        -- Update or add patch
+        -- Update or add patch (re-encode lua_value at emit time for correctness
+        -- against mutable post-assignment mutations like t.a = {}; t.a.x = 1).
         local found = false
         for _, p in ipairs(patches) do
             if p.key == k then
-                p.encoded_value = encoded
                 p.lua_value = v
                 found = true
                 break
             end
         end
         if not found then
-            patches[#patches + 1] = { key = k, encoded_value = encoded, lua_value = v }
+            patches[#patches + 1] = { key = k, lua_value = v }
         end
 
         -- Remove from deleted if previously deleted
@@ -602,8 +599,8 @@ local function encode_lazy_object_walking_with_patches(t, patches, deleted)
             local v
             local patch = patched_keys[k]
             if patch then
-                -- Use patched value (already encoded)
-                parts[#parts + 1] = encode_string(k) .. ":" .. patch.encoded_value
+                -- Re-encode at emit time so mutations after assignment are reflected.
+                parts[#parts + 1] = encode_string(k) .. ":" .. encode(patch.lua_value)
             else
                 -- Use original or cached value
                 local cached = rawget(t, k)
@@ -622,7 +619,7 @@ local function encode_lazy_object_walking_with_patches(t, patches, deleted)
     for _, p in ipairs(patches) do
         local rc = C.qjson_cursor_field_bytes(t._cur, p.key, #p.key, sz_a, sz_b)
         if rc == QJSON_NOT_FOUND then
-            parts[#parts + 1] = encode_string(p.key) .. ":" .. p.encoded_value
+            parts[#parts + 1] = encode_string(p.key) .. ":" .. encode(p.lua_value)
         elseif rc ~= QJSON_OK then
             check(rc)  -- propagate unexpected errors
         end
@@ -649,7 +646,7 @@ local function encode_with_patches(t)
             replacements[#replacements + 1] = {
                 start = tonumber(sz_a[0]),
                 end_ = tonumber(sz_b[0]),
-                value = p.encoded_value,
+                value = encode(p.lua_value),  -- re-encode at emit time
             }
         elseif rc == QJSON_NOT_FOUND then
             has_new_field = true

tests/lua/lazy_patch_spec.lua

@@ -127,10 +127,23 @@ describe("Lazy Patch - type changes", function()
         assert.are.equal(10, parsed.a.x)
     end)
 
+    it("mutation of patch value after assignment is reflected in encode", function()
+        -- Regression: encoded_value was cached at assignment time; mutations to
+        -- the patched table were invisible to encode because it used the stale
+        -- encoded_value instead of re-encoding lua_value at emit time.
+        local t = qjson.decode('{"a":1}')
+        t.a = {x = 1}       -- records patch; lua_value is the table {x=1}
+        t.a.x = 2           -- mutates the table in lua_value; must show up in encode
+        local out = qjson.encode(t)
+        local cjson = require("cjson")
+        local parsed = cjson.decode(out)
+        assert.are.equal(2, parsed.a.x)
+    end)
+
     it("changes scalar to array", function()
         local t = qjson.decode('{"a":1}')
         t.a = {10, 20, 30}
-        local out = qjson.encode(t)
+
         local cjson = require("cjson")
         local parsed = cjson.decode(out)
         assert.are.same({10, 20, 30}, parsed.a)