From 40e342f2217bc9639751f258b76c36cdd1f0334f Mon Sep 17 00:00:00 2001
From: charles <charles@tipsy.codes>
Date: Mon, 4 May 2026 23:12:20 -0700
Subject: [PATCH 1/2] Document Protobuf spec validation

---
 README.md | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index 7f99f06..9b0648b 100644
--- a/README.md
+++ b/README.md
@@ -283,6 +283,29 @@ after parsing is faster. For workloads that read every field the costs
 invert; for workloads that read a handful of fields from large messages roto
 wins.
 
-## Literature
+## Protobuf Spec Validation
 
-https://protobuf.dev/programming-guides/encoding/
+The goal is to validate roto's implementation against the Proto3 specification.
+
+### Supported Features
+
+- **Scalar Types**: `double`, `float`, `int32`, `int64`, `uint32`, `uint64`, `sint32`, `sint64`, `fixed32`, `fixed64`, `sfixed32`, `sfixed64`, `bool`, `string`, `bytes`.
+- **Messages**: Top-level and nested message definitions.
+- **Enums**: Enum definitions with `from_i32` conversion.
+- **Field Labels**: Singular and `repeated` fields.
+
+### Unsupported Features
+
+- **`oneof` Fields**: Not currently supported in code generation.
+- **`map` Fields**: Not currently supported.
+- **Packed Repeated Fields**: `roto` expects individual tags for all repeated elements; it does not support the packed encoding used for scalar numeric types in Proto3.
+- **Reserved Fields**: `reserved` statements are ignored.
+- **Services**: `service` and `rpc` definitions are ignored.
+- **Options**: Field and message options are ignored.
+
+### Tasks
+
+- [x] Analyze `roto/codegen` to determine which protobuf constructs are supported during code generation.
+- [x] Analyze `roto/runtime` to determine which wire types and protobuf types are supported during reading and writing.
+- [x] Compare findings with the Proto3 spec (https://protobuf.dev/reference/protobuf/proto3-spec/).
+- [x] Document supported and unsupported features in the README.

From e5c2479985d4d7e46d3b1a28081ffd6b4754d4c5 Mon Sep 17 00:00:00 2001
From: charles <charles@tipsy.codes>
Date: Mon, 4 May 2026 23:38:11 -0700
Subject: [PATCH 2/2] Document unsupported Proto3 features

---
 README.md | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/README.md b/README.md
index 9b0648b..0f1feb0 100644
--- a/README.md
+++ b/README.md
@@ -296,6 +296,8 @@ The goal is to validate roto's implementation against the Proto3 specification.
 
 ### Unsupported Features
 
+- **Default Values**: Missing fields return `RotoError::FieldNotFound` instead of the Proto3 default value (e.g., `0` or `""`).
+- **Field Presence**: No `has_field()` methods are generated to distinguish between a field being absent and a field being set to its default value.
 - **`oneof` Fields**: Not currently supported in code generation.
 - **`map` Fields**: Not currently supported.
 - **Packed Repeated Fields**: `roto` expects individual tags for all repeated elements; it does not support the packed encoding used for scalar numeric types in Proto3.