diff --git a/.codespellrc b/.codespellrc
index d8c810ec..ec6dbc3a 100644
--- a/.codespellrc
+++ b/.codespellrc
@@ -1,3 +1,3 @@
 [codespell]
-skip = *.lock,*.json,submodules/*,.venv/*,.git,docs/node_modules/*
+skip = *.lock,*.json,submodules/*,.venv/*,.git,docs/node_modules/*,src/xorl/ops/quack/*,src/xorl/ops/linear_attention/flashqla/*
 ignore-words-list = dout,te,subtile,parm,mot,numer,notin
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 4fad13c9..aea412a2 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,6 +1,10 @@
 default_stages: [pre-commit, pre-push, manual]
-exclude: ^(submodules/|\.venv/|src/xorl/ops/quack/)
-
+# Vendored trees and byte-contract-gated files are never rewritten by any
+# hook: quack/ and flashqla/ are third-party snapshots (see their VENDORED.md),
+# and bi_families_v2.py is vendored byte-identical into the serving engine
+# with both copies sha256-gated, so it keeps that engine's formatting
+# (black, 88 columns). See src/xorl/ops/README.md.
+exclude: ^(submodules/|\.venv/|src/xorl/ops/quack/|src/xorl/ops/linear_attention/flashqla/|src/xorl/ops/bi_families_v2\.py$)
 repos:
   - repo: https://github.com/pre-commit/pre-commit-hooks
     rev: v5.0.0
@@ -28,11 +32,6 @@ repos:
       - id: ruff
         args: [--fix-only]
       - id: ruff-format
-        # bi_families_v2.py is vendored byte-identical into the serving engine
-        # and both copies are sha256-gated, so it carries that engine's
-        # formatting (black, 88 columns). Reformatting it here at 120 would
-        # break the byte-equality the contract depends on. Lint still runs.
-        exclude: ^src/xorl/ops/bi_families_v2\.py$
   - repo: https://github.com/codespell-project/codespell
     rev: v2.4.1
     hooks:
diff --git a/pyproject.toml b/pyproject.toml
index cb86f301..fefd626e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -142,6 +142,16 @@ where = ["src"]
 [tool.ruff]
 target-version = "py312"
 line-length = 120
+# Vendored trees and the byte-contract-gated serving copy are never linted or
+# formatted by first-party tooling (see src/xorl/ops/README.md).
+# force-exclude keeps this true even when paths are passed explicitly, which
+# is how pre-commit invokes ruff.
+force-exclude = true
+extend-exclude = [
+  "src/xorl/ops/quack",
+  "src/xorl/ops/linear_attention/flashqla",
+  "src/xorl/ops/bi_families_v2.py",
+]
 
 [tool.ruff.lint]
 ignore = ["C901", "E501", "E741", "W605", "C408"]
diff --git a/src/xorl/ops/README.md b/src/xorl/ops/README.md
new file mode 100644
index 00000000..94559c56
--- /dev/null
+++ b/src/xorl/ops/README.md
@@ -0,0 +1,45 @@
+# xorl.ops
+
+Compute kernels and autograd ops. This README is the map: what each
+subtree is, what may be edited, and where things are headed
+(reorganization plan: [issue #78](https://github.com/togethercomputer/xorl/issues/78)).
+
+## Edit policies
+
+Three kinds of code live here with three different rules:
+
+| kind | rule |
+| --- | --- |
+| **Vendored** — `quack/`, `linear_attention/flashqla/` | Never hand-edit, lint, or reformat. Each tree carries a `VENDORED.md` with provenance and the local-patch ledger. First-party tooling skips them (`[tool.ruff]` excludes in `pyproject.toml`; top-level `exclude:` in `.pre-commit-config.yaml`). |
+| **Byte-contract-gated** — `bi_families_v2.py` | Vendored byte-identical into the serving engine; both copies are sha256-gated. Any edit here without the paired serving-side edit breaks the gate. It keeps the engine's formatting (black, 88 columns) and is excluded from all rewriting hooks. |
+| **First-party** — everything else | Normal rules. |
+
+## Map (current)
+
+- `bi_families_v2.py`, `batch_invariant_ops.py`, `bi_gemm_configs.py`,
+  `exact_sampling_transforms.py`, `rope_class_b.py`, `canonical_moe_leaf.py`,
+  `canonical_moe_cast.py`, `fused_silu_and_mul.py`, `kernel_config_pin.py`,
+  `block_fp8_native.py` — the **serving-parity (exact) contract family**:
+  byte-pinned programs shared with the serving engine. The `bi_` / `exact_` /
+  `canonical_` / `class_b` prefixes are historical names for the same
+  concept. Planned home: `ops/exact/` (#78 phase 3).
+- `loss/` — the CE/selected-logprob kernel stack **plus** (for now) the RL
+  objective functions; the objectives move to `xorl/objectives/`
+  (#78 phase 2).
+- `moe/` — MoE expert compute backends (triton/quack/native, LoRA variants).
+  `ep_kernels/` (DeepEP sort/scatter) merges in here (#78 phase 5).
+- `linear_attention/` — GDN/linear-attention kernels; also currently hosts
+  the `GatedDeltaNet` layer class and the vendored `flashqla/` tree
+  (layer moves to `models/layers/`, vendored tree to `ops/_vendored/`, #78).
+- `ssm/` — Mamba-2 kernels; also currently hosts the `Mamba2Mixer` layer
+  class (same plan as above).
+- `quantize/` — NF4/INT4/FP4/FP8 quantization codecs and fake-quant ops.
+- `glm5_kernels/`, `dsv4/` — model-family-specific kernels; planned home:
+  `models/transformers/{glm5,deepseek_v4}/kernels/` (#78 phase 4).
+- `quack/` — vendored (see above).
+
+## What does NOT belong here
+
+New `nn.Module` layer classes (→ `models/layers/`), RL objectives
+(→ `xorl/objectives/` once it exists), and orchestration logic. `ops/` is
+for kernels and the autograd boundaries directly over them.
diff --git a/src/xorl/ops/quack/VENDORED.md b/src/xorl/ops/quack/VENDORED.md
new file mode 100644
index 00000000..99088f29
--- /dev/null
+++ b/src/xorl/ops/quack/VENDORED.md
@@ -0,0 +1,26 @@
+# Vendored: QuACK (partial fork)
+
+This directory is a vendored, locally-patched subset of
+[QuACK](https://github.com/Dao-AILab/quack) (Wentao Guo, Ted Zadouri,
+Tri Dao — CuTeDSL kernels), snapshotted at upstream `0.4.1`
+(see `__init__.py:__version__`).
+
+It is a *partial* fork: modules in this tree still import helper modules
+(`copy_utils`, `layout_utils`, …) from the separate PyPI dependency
+`quack-kernels` pinned in `pyproject.toml`, so the pinned PyPI version and
+this tree must stay compatible.
+
+Known local additions/patches (not upstream):
+
+- `cute_dsl_elf_fix.py` — works around cutlass#3161 (duplicate `.text`
+  section flags break MCJIT in multi-process loads).
+- `cute_dsl_mlir_threading.py` — works around cutlass#3062 (leaked LLVM
+  thread pools exhaust pthreads across compiles).
+
+## Edit policy
+
+Do not hand-edit, lint, or reformat files in this tree. First-party tooling
+skips it (see `pyproject.toml` `[tool.ruff]` excludes and the top-level
+`exclude:` in `.pre-commit-config.yaml`). Fixes should go upstream first;
+a local patch that cannot wait must be listed above with its upstream
+issue/PR so the next re-vendor can reconcile it.