diff --git a/PLAN.md b/PLAN.md
index 59090b24e2564c73554230e8b45a34f556b14401..649a077930bb5873d3835dedc58e58d7318c422e 100644
--- a/PLAN.md
+++ b/PLAN.md
@@ -447,7 +447,71 @@ Both codegen modes implement it: runtime mode in `pb.codec`, full (inline)
 mode emits per-message capture/re-emit blocks. Tests live in
 `test/unknown_test.lua` and run against both modes.
 
-### 4.6 gRPC service descriptors
+### 4.6 Protobuf editions  *(not implemented; tracking)*
+
+We advertise `CodeGeneratorResponse_FEATURE_PROTO3_OPTIONAL` only, not
+`FEATURE_SUPPORTS_EDITIONS`. If protoc is invoked against an
+`edition = "2023";` file with our plugin, it errors out — mainline
+refuses to call an editions-unaware plugin.
+
+**What editions changes.** Editions replaces the proto2-vs-proto3 split
+with one language whose behavior is controlled by per-file / per-field
+`FeatureSet` annotations. The knobs that matter for us:
+
+- `field_presence = EXPLICIT | IMPLICIT | LEGACY_REQUIRED` — presence
+  becomes an opt-in/opt-out per field instead of a syntax-wide default.
+- `repeated_field_encoding = PACKED | EXPANDED` — per-field opt-out
+  from packed encoding for scalar `repeated` fields.
+- `enum_type = OPEN | CLOSED` — closed enums route unknown values to
+  unknown fields (proto2 semantics) instead of round-tripping the int.
+- `utf8_validation = VERIFY | NONE` — per-field strictness on `string`.
+- `json_format = ALLOW | LEGACY_BEST_EFFORT` — JSON behavior overrides.
+
+**What we'd actually gain.** Honestly modest, ranked by user-visible
+value:
+
+1. **Per-field packed opt-out** — the only knob proto3 doesn't expose
+   today. Real interop scenarios (talking to legacy proto2 services,
+   certain gRPC gateways) sometimes need expanded encoding on a
+   specific field. Right now our users have no escape hatch.
+2. **Migration path off proto3.** Proto3 syntax is being phased out in
+   favor of edition 2023. This is a forcing function, not a feature
+   win — at some point users will write `edition = "2023";` and we'll
+   need to read it.
+3. **Explicit presence by default** without the `optional` keyword (and
+   the synthetic-oneof wart it creates today).
+4. **Per-field UTF-8 toggle** for users carrying not-quite-UTF-8 bytes
+   in `string` fields for legacy compat.
+5. **Closed enums** for users who want proto2-style unknown-value
+   routing.
+6. **`LEGACY_REQUIRED` field presence** — niche; only way to express
+   "required" without writing proto2.
+
+**What it would cost.** Setting the bit is one line; the work is:
+
+- Plugin (`cmd/protoc-gen-tarantool/internal/gen`) needs to read each
+  field's resolved `FeatureSet` and drive codegen off it (packed,
+  presence, UTF-8 strictness, enum closedness) instead of the proto3
+  defaults baked in.
+- Runtime parser (`runtime/pb/parser.lua`) needs to accept
+  `edition = "2023";` and the `features = { ... }` option syntax.
+- `runtime/pb/dynamic.lua` and `runtime/pb/fileset.lua` need to
+  propagate resolved features onto the descriptor. The descriptor
+  contract in `docs/codegen.md` would gain a `features` field per
+  message/field/enum.
+- `CodeGeneratorResponse` needs `minimum_edition` / `maximum_edition`
+  set, else protoc rejects an editions-supporting plugin.
+- The conformance suite has editions-specific buckets we'd start
+  encountering.
+
+**Current verdict.** Deferred. No user pull today, proto3 will keep
+working for years, and the practical-win list above is mostly small
+quality-of-life items rather than blocking gaps. Revisit when (a)
+someone needs per-field packed control, (b) the conformance suite
+starts gating on editions, or (c) protoc deprecates proto3 syntax
+hard enough that real users hit the error.
+
+### 4.7 gRPC service descriptors
 
 ```lua
 M.Greeter_service = {
@@ -570,7 +634,9 @@ ## 8. Non-goals (for now)
 
 - **proto2** syntax — spec is more complex (required, default values,
   groups), real demand is rare on Tarantool.
-- **Protobuf editions** beyond what proto3 enables.
+- **Protobuf editions** beyond what proto3 enables — see §4.6 for
+  the per-feature analysis (what we'd gain, what it would cost, the
+  conditions that would force a revisit).
 - **HTTP/2 termination** for gRPC. Push it to Envoy; see
   [`docs/specs/grpc_transports.md`](docs/specs/grpc_transports.md).
   Connect-JSON over HTTP/1.1 is the default external transport.