diff --git a/packages/chord/docs/next/design.md b/packages/chord/docs/next/design.md
index d40d82677..517276db3 100644
--- a/packages/chord/docs/next/design.md
+++ b/packages/chord/docs/next/design.md
@@ -442,7 +442,8 @@ drops, folds or resets.
 - **JSON plus `Uint8Array` leaves**, with a bytes schema type, defined independently of the transport. Every link
   carries the same `Message` through its codec (section 22); parts are encoded at their origin; byte segments travel
   raw, never base64. Same-host calls (no link) pass values by reference.
-- Schemas are TypeBox and must describe data (no callbacks, no native types, no runtime codecs). Method arguments are
+- Schemas are plain JSON Schema built with `@earendil-works/pi-schema` (decision "The schema switch") and must
+  describe data (no callbacks, no native types, no runtime codecs); `format` is an annotation, never checked. Method arguments are
   validated at the provider for every caller against closed schemas (section 5, R7, Q12, Q15); results and state are
   never validated (section 30). Values are immutable by convention once handed over (Delta's rule): nobody mutates a
   value it got, and nothing is copied or frozen to enforce it. There is no development mode (R9): one behavior
@@ -572,7 +573,7 @@ host.serve(Notes, ({ session }, principal, self) =>
   (`invalid/member` outside it).
 - **Params** (owner, 2026-10-21/22): a flat record of required fields, each `str()`, `int()`, `bool()` or `oneOf(...)`
   of string literals, constraints allowed (`str({ pattern })`, `int({ min: 0 })`); no defaults, optional, nested or
-  unknown fields. Checked for every caller with one compiled closed-object TypeBox check (a missing or extra field
+  unknown fields. Checked for every caller with one compiled closed-object pi-schema check (a missing or extra field
   fails `invalid/params`). The identity key is the field values in declared order, each escaped, joined with `|`.
   Params are never copied or frozen: the object keeps the caller's object, immutable by convention.
 - **Arguments (R7, Q12, Q15):** always validated with the provider's schema, whoever the caller is (trusted code is
@@ -592,8 +593,8 @@ host.serve(Notes, ({ session }, principal, self) =>
   link protocol (adding one bumps the protocol version; a receiver rejects unknown reasons; a test pins the list):
   `invalid` (`args`, `params`, `member`, `host_address`, `reentrant`, `read_after_bulk`, `cycle`), `contract_mismatch`
   (`updating`), `forbidden` (`revoked`), `gone`, `not_ready`, `released` (`ended`, `closed`, `settled`, `version`, `discarded`; none for a holder's own release), `too_large` (`part`), `unavailable` (`locked`,
-  `park_timeout`, `busy`, `storage_failed`, `undeclared`: a registry no plugin serves here, slice 8), `aborted`. A failed check names TypeBox's instance path ("unknown field", "missing", else TypeBox's
-  message; keys containing `/` or `~` make the path ambiguous, documented). Plugins throw `PluginError(code, message,
+  `park_timeout`, `busy`, `storage_failed`, `undeclared`: a registry no plugin serves here, slice 8), `aborted`. A failed check names pi-schema's JSON Pointer path ("unknown field", "missing", else
+  pi-schema's message; `~` and `/` in keys escaped as `~0`, `~1`). Plugins throw `PluginError(code, message,
   details?)` for codes of their own; anything else crosses a link as the plugin code `internal` with its message, never
   a stack or a cause; plugin errors never use Chord's codes. An error rebuilt from the wire is not copied and only its
   envelope is checked; a malformed envelope is a protocol error.
@@ -1997,7 +1998,7 @@ validation, no clone of snapshots or ops.
 - **The protocol version** travels in `hello`; hosts of different versions refuse each other (a web page reloads for
   a newer server). Error reasons and message kinds are part of it. Until p3 ships, changes keep `PROTOCOL_VERSION` 1
   (nothing is deployed); after that every message or reason change bumps it.
-- **One typed `Message`** (owner, 2026-10-22, "Wire protocol"): a TypeBox schema `MESSAGE`, a tagged union over
+- **One typed `Message`** (owner, 2026-10-22, "Wire protocol"): a pi-schema schema `MESSAGE`, a tagged union over
   `kind`, from which the protocol types derive; every decoded message is checked against it (compiled once) unless
   the link is trusted (section 3). Kinds:
 
@@ -2416,7 +2417,7 @@ const accepted = checkAccepts(NotesV2, {
   providers fail at declaration naming the member; unknown keys and wrong shapes are rejected.
 - **The fingerprint** is a hash (`hash64`, portable, not a security boundary) of a schema-aware, data-only normal form
   (`NORMAL_FORM_VERSION`, tied to the protocol): annotations dropped only on schema nodes, `required`/`enum` sorted,
-  union and intersection order kept (it is meaning: defaults), a whitelist of TypeBox keywords, executable features
+  union and intersection order kept (it is meaning: defaults), a whitelist of JSON Schema keywords, executable features
   rejected; bytes are a `{ type: "bytes" }` data marker. Schemas are deep-copied into a private history (never frozen; immutable by convention).
 - **Schema helpers:** `str num int bool nul lit oneOf union obj arr map opt bytes unknown` and `type Static`.
 - Chord wraps state mappings as a derive and diffs per object and version (section 22); members an old consumer does not know do
diff --git a/packages/chord/docs/next/layer-1.md b/packages/chord/docs/next/layer-1.md
index 505fe7294..0129181df 100644
--- a/packages/chord/docs/next/layer-1.md
+++ b/packages/chord/docs/next/layer-1.md
@@ -14,7 +14,7 @@ checked, what a principal key is, what an error is. Pure functions, types and we
 Source: `packages/chord/src/next/contracts/` (declarations) and `packages/chord/src/next/data/` (per-call checks,
 principals, errors), split into files by concept. Everything else under `src/next/` is the frozen old kernel: never
 imported, never edited. Reused: `src/context/` (`Context`, `BACKGROUND_CONTEXT`, `context.telemetry`) and
-`src/json.ts` (`JsonValue`), both unchanged. Schemas are TypeBox 1.3 (`typebox` in `node_modules`).
+`src/json.ts` (`JsonValue`), both unchanged. Schemas were TypeBox 1.3 when L1 was built; since the schema switch (2026-11-01) they are pi-schema's plain JSON Schema (design §3 "Values"). The TypeBox details below are historical.
 
 ## 1. Values
 
diff --git a/packages/chord/docs/next/slice-3a.md b/packages/chord/docs/next/slice-3a.md
index 4605bb95c..a6dba100b 100644
--- a/packages/chord/docs/next/slice-3a.md
+++ b/packages/chord/docs/next/slice-3a.md
@@ -89,7 +89,7 @@ if (notes.variant === "reader") console.log(notes.notes.value);   // narrowed by
 | u32 header length, big-endian | header JSON (UTF-8) | part 0 | part 1 | … |
 ```
 
-- **One format on every link.** The header is a JSON object, a tagged union over `kind`, defined as a TypeBox schema;
+- **One format on every link.** The header is a JSON object, a tagged union over `kind`, defined as a schema (TypeBox then, pi-schema since the schema switch);
   every received header is checked with the compiled schema (the wire is a trust boundary; skipping it on trusted IPC
   links comes with IPC in slice 4). The header lists its parts: `parts: [{ json, bytes }]`, the JSON text's byte length and
   the byte lengths of the segments that follow it (`bytes: []` for state parts and arguments without bytes).
@@ -125,7 +125,7 @@ if (notes.variant === "reader") console.log(notes.notes.value);   // narrowed by
 Replaces the JSON-header framing of section 2 (`| u32 header length | header JSON | parts |`); the message kinds, ids,
 races and rules of section 2 stay.
 
-- **`Message`** is a tagged union defined once as a TypeBox schema (`MESSAGE`; `type Message = Static<typeof
+- **`Message`** is a tagged union defined once as a schema (TypeBox then, pi-schema since the schema switch) (`MESSAGE`; `type Message = Static<typeof
   MESSAGE>`): `hello { protocol, incarnation }`, `hold { hold, type, version, fingerprint, params }`, `release { hold
   }`, `call { call, hold, method, args? }`, `cancel { call }`, `bound { hold, variant, members: [{ member, value }],
   failed: [{ member, error }] }`, `state { holds: [{ hold, members: [{ member, ops }], failed: [...] }] }`, `failed {
diff --git a/packages/chord/docs/next/slices.md b/packages/chord/docs/next/slices.md
index 452528592..28e094cd5 100644
--- a/packages/chord/docs/next/slices.md
+++ b/packages/chord/docs/next/slices.md
@@ -170,15 +170,11 @@ deleted (the slice's spec and code are the record). Moved here from `carry-over.
   slice 3b.)
 - **The park deadline's per-type override** is not built: a parked call waits the reference's `readyTimeout`. Build
   it only if a real case needs it. (Slice 3b spec.)
-- Failed-check paths are TypeBox's instance paths (ambiguous for keys containing `/` or `~`); documented, not fixed.
-  (L1.)
 - No CBOR; revisit only if benchmarks show encoding as a bottleneck (slice 3a's and 4a's do not). (L2 decisions.)
 - **One N on every host:** a relay forwards calls at once, so a worker announcing a smaller N than the relay's could
   see more running calls of one origin than it accepts (a protocol error). Every host announces 256; per-link N, if
   ever needed, must bound the relay's forwarding too. (Slice 4a rework.)
 - **The Durable conversation view's size on re-hold** is a known cost until pi #11327 (windowed view) lands. (Slice 4.)
-- **`map(bytes())` is refused at declaration** ("unsupported keyword `~refine`"): TypeBox's `Record` copies the bytes
-  schema's check as an enumerable key, which the snapshot walk refuses. An L1 bug found in slice 3a, not fixed yet.
 
 ### Later: reload (when a case needs it)