Implement generic-profile delta (SPEC §10a)

Full producer + consumer for generic-profile keyed-row delta, byte-for-byte
interoperable with gcf-go:

- GenericSet, GenericDeltaPayload
- generic_pack_root (gcf-pack-root-v1) with collision-free cell
  canonicalization decoupled from the wire encoder; fields and records sort
  by UTF-8 byte order to match Go's sort.Strings
- diff_generic_sets (blessed producer path), encode_generic_full,
  encode_generic_delta
- decode_generic_full, decode_generic_delta (consumer wire parsing)
- verify_generic_delta (atomic apply + new_root verification)

Delta is opt-in and bilateral; encode_generic is unchanged. Adds a unit
suite mirroring gcf-go and conformance-runner support for the four generic
delta operations (12 shared fixtures). Bumps version to 2.3.0.

Author: blackwell-systems

CHANGELOG.md

@@ -1,5 +1,22 @@
 # Changelog
 
+## v2.3.0 (unreleased)
+
+### Generic-profile delta encoding (SPEC §10a)
+
+- Full producer + consumer implementation of generic-profile delta, byte-for-byte interoperable with `gcf-go`:
+  - `GenericSet` (keyed record set), `GenericDeltaPayload`
+  - `generic_pack_root` (`gcf-pack-root-v1`, generic profile) with a purpose-built cell canonicalization decoupled from the wire cell encoder: collision-free (null/bool/number bare, strings always quoted) and record-safe. Fields and records sort by UTF-8 byte order to match Go's `sort.Strings`.
+  - `diff_generic_sets` (the blessed producer path; centralizes the keyed-diff invariants), `encode_generic_full`, `encode_generic_delta`
+  - `decode_generic_full`, `decode_generic_delta` (consumer wire parsing)
+  - `verify_generic_delta` (atomic apply + `new_root` verification)
+- Delta is opt-in and bilateral; the existing `encode_generic` path is unchanged (backward compatible).
+
+### Tests
+
+- Unit suite mirroring `gcf-go`: self-proving round-trip (diff -> encode -> apply -> recomputed root), determinism / row-order invariance, no-type-collision canonicalization, every invariant/error path, full-payload wire round-trip, the complete server -> wire -> consumer end-to-end loop, and malformed-wire-fails-closed.
+- Conformance runner support for `generic-pack-root`, `generic-delta`, `generic-delta-verify`, `generic-delta-decode` (12 shared fixtures); verified to produce identical pack roots and delta wire to `gcf-go`.
+
 ## v2.2.2 (2026-07-10)
 
 ### Fixes

src/gcf/__init__.py

@@ -39,6 +39,17 @@
 from .delta import encode_delta
 from .encode import encode
 from .generic import encode_generic, GenericOptions
+from .generic_delta import (
+    GenericSet,
+    GenericDeltaPayload,
+    generic_pack_root,
+    diff_generic_sets,
+    encode_generic_full,
+    encode_generic_delta,
+    decode_generic_full,
+    decode_generic_delta,
+    verify_generic_delta,
+)
 from .session import Session, encode_with_session
 from .decode_generic import decode_generic
 from .stream import StreamEncoder
@@ -64,6 +75,15 @@
     "encode_generic",
     "GenericOptions",
     "encode_with_session",
+    "GenericSet",
+    "GenericDeltaPayload",
+    "generic_pack_root",
+    "diff_generic_sets",
+    "encode_generic_full",
+    "encode_generic_delta",
+    "decode_generic_full",
+    "decode_generic_delta",
+    "verify_generic_delta",
 ]
 
-__version__ = "2.2.2"
+__version__ = "2.3.0"