From 484435a31874ad00c68fd5040d239cd7ec335646 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 31 Mar 2026 17:51:43 +0000
Subject: [PATCH 1/3] Initial plan


From e682fe2cf0833ecdeb1a38a372e34ae6645ce9f0 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Tue, 31 Mar 2026 18:00:54 +0000
Subject: [PATCH 2/3] Add FixedPointDecimals package extension for FixedDecimal
 -> Dec128 representation

Agent-Logs-Url: https://github.com/ancapdev/LightBSON.jl/sessions/36139d1b-9e70-4c41-8782-69069d79253d

Co-authored-by: ancapdev <2189089+ancapdev@users.noreply.github.com>
---
 Project.toml                          | 12 ++++++++++--
 ext/LightBSONFixedPointDecimalsExt.jl | 15 +++++++++++++++
 test/fixed_decimal_tests.jl           | 26 ++++++++++++++++++++++++++
 test/runtests.jl                      |  1 +
 4 files changed, 52 insertions(+), 2 deletions(-)
 create mode 100644 ext/LightBSONFixedPointDecimalsExt.jl
 create mode 100644 test/fixed_decimal_tests.jl

diff --git a/Project.toml b/Project.toml
index 0c84a51..6567468 100644
--- a/Project.toml
+++ b/Project.toml
@@ -20,6 +20,7 @@ WeakRefStrings = "ea10d353-3f73-51f8-a26c-33c1cb351aa5"
 DataStructures = "0.18, 0.19"
 Dates = "1"
 DecFP = "1"
+FixedPointDecimals = "0.5, 0.6"
 FNVHash = "0.1"
 JSON3 = "1"
 Sockets = "1"
@@ -28,10 +29,17 @@ Transducers = "0.4"
 UUIDs = "1"
 UnsafeArrays = "1"
 WeakRefStrings = "1"
-julia = "1.8"
+julia = "1.9"
+
+[weakdeps]
+FixedPointDecimals = "fb4d412d-6eee-574d-9565-ede6634db7b0"
+
+[extensions]
+LightBSONFixedPointDecimalsExt = "FixedPointDecimals"
 
 [extras]
+FixedPointDecimals = "fb4d412d-6eee-574d-9565-ede6634db7b0"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 
 [targets]
-test = ["Test"]
+test = ["Test", "FixedPointDecimals"]
diff --git a/ext/LightBSONFixedPointDecimalsExt.jl b/ext/LightBSONFixedPointDecimalsExt.jl
new file mode 100644
index 0000000..135f748
--- /dev/null
+++ b/ext/LightBSONFixedPointDecimalsExt.jl
@@ -0,0 +1,15 @@
+module LightBSONFixedPointDecimalsExt
+
+using LightBSON
+using FixedPointDecimals
+using DecFP
+
+@inline LightBSON.bson_representation_type(::Type{FixedDecimal{T, f}}) where {T, f} = Dec128
+
+@inline LightBSON.bson_representation_convert(::Type{Dec128}, x::FixedDecimal{T, f}) where {T, f} =
+    Dec128(x.i, -f)
+
+@inline LightBSON.bson_representation_convert(::Type{FixedDecimal{T, f}}, x::Dec128) where {T, f} =
+    reinterpret(FixedDecimal{T, f}, T(x * Dec128(1, f)))
+
+end
diff --git a/test/fixed_decimal_tests.jl b/test/fixed_decimal_tests.jl
new file mode 100644
index 0000000..b232863
--- /dev/null
+++ b/test/fixed_decimal_tests.jl
@@ -0,0 +1,26 @@
+using FixedPointDecimals
+
+@testset "FixedDecimal" begin
+
+@testset "FixedDecimal{Int64, $f} roundtrip" for (f, v) in [(0, 125), (2, 1.25), (4, 1.25)]
+    buf = empty!(fill(0xff, 1000))
+    writer = BSONWriter(buf)
+    x = FixedDecimal{Int64, f}(v)
+    writer["x"] = x
+    close(writer)
+    @test BSONReader(buf, StrictBSONValidator())["x"][Dec128] == Dec128(x.i, -f)
+    @test BSONReader(buf, StrictBSONValidator())["x"][FixedDecimal{Int64, f}] == x
+end
+
+@testset "FixedDecimal precise conversion" begin
+    x = FixedDecimal{Int64, 2}(1.23)
+    @test Dec128(x.i, -2) == d128"1.23"
+    buf = empty!(fill(0xff, 1000))
+    writer = BSONWriter(buf)
+    writer["x"] = x
+    close(writer)
+    @test BSONReader(buf, StrictBSONValidator())["x"][Dec128] == d128"1.23"
+    @test BSONReader(buf, StrictBSONValidator())["x"][FixedDecimal{Int64, 2}] == x
+end
+
+end
diff --git a/test/runtests.jl b/test/runtests.jl
index f07b703..132bedc 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -23,4 +23,5 @@ struct EmptyStruct end
     include("object_id_tests.jl")
     include("convenience_tests.jl")
     include("representation_tests.jl")
+    include("fixed_decimal_tests.jl")
 end

From e700c7b56715272223c610fbff5e7bc491ee72fd Mon Sep 17 00:00:00 2001
From: Christian Rorvik <christian@graystonetrading.com>
Date: Tue, 31 Mar 2026 21:42:18 +0200
Subject: [PATCH 3/3] Apply suggestion from @ancapdev

---
 Project.toml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Project.toml b/Project.toml
index 6567468..4d62a41 100644
--- a/Project.toml
+++ b/Project.toml
@@ -1,7 +1,7 @@
 name = "LightBSON"
 uuid = "a4a7f996-b3a6-4de6-b9db-2fa5f350df41"
 authors = ["Christian Rorvik <christian.rorvik@gmail.com>"]
-version = "1.4.0"
+version = "1.5.0"
 
 [deps]
 DataStructures = "864edb3b-99cc-5e75-8d2d-829cb0a9cfe8"