diff --git a/quest/m1/auth/request-token.md b/quest/m1/auth/request-token.md
index 40676e2eecf..d1d4bc40553 100644
--- a/quest/m1/auth/request-token.md
+++ b/quest/m1/auth/request-token.md
@@ -17,12 +17,33 @@ no longer fails the session; this quest gives it meaning.
 ## Plan
 
 - Decode with the SETUP option's structure and rules
-  (`rs/moq-net/src/ietf/token.rs`, `js/net/src/ietf/token.ts`): `USE_VALUE` yields the token, `REGISTER` is a value since we
-  advertise no `MAX_AUTH_TOKEN_CACHE_SIZE`, and `DELETE` or `USE_ALIAS`
-  closes with `PROTOCOL_VIOLATION`. Both decoder families change: the strict
+  (`rs/moq-net/src/ietf/token.rs`, `js/net/src/ietf/token.ts`): `USE_VALUE` yields the token. `REGISTER` closes the session with
+  `AUTH_TOKEN_CACHE_OVERFLOW` (0x13): we
+  advertise no `MAX_AUTH_TOKEN_CACHE_SIZE`, so the limit is 0, and draft-21
+  §8.9 says overflowing it MUST close the session. Only SETUP falls back to
+  USE_VALUE (§9.1.4). `DELETE` or `USE_ALIAS` closes with
+  `UNKNOWN_AUTH_TOKEN_ALIAS` (0x17): a cache size of 0 "prohibits the use
+  of token Aliases" (§9.1.3), so no alias is ever registered. §8.9 says to
+  reject the message, but 0x17 exists only as a Session Termination Code
+  (§12.2), not a Request Error Code. Record that close as a deviation
+  under "moq-transport" in `doc/concept/standard.md`. A token structure that does not
+  decode closes with `KEY_VALUE_FORMATTING_ERROR`. Paul Gregoire's
+  validator checks the REGISTER and malformed-token codes (decided
+  2026-10-04; aliases decided 2026-10-05). Both decoder families change: the strict
   `decode_params!` path, where each request reads the repeatable key into an
   ignored `Vec<Opaque>`, and draft-14's `Parameters::skip`, which consumes it
   unread. `js/net` keeps every instance in `Parameters` and reads none.
+- 0x13 and 0x17 join the shared session registry: `SessionError`
+  (`rs/moq-net/src/error.rs`) and `SessionCode` (`js/net/src/error.ts`).
+  Lite codes below 32 carry moq-transport's meaning, so add both rows to the
+  Session Error Codes table in `drafts/draft-lcurley-moq-lite.md` and to
+  `session_codes_round_trip`, as [Malformed moq-transport
+  input](/quest/m2/ietf-malformed-close.md) does for its codes. No
+  per-version mapping. That adds two codes to moq-lite's wire registry.
+- Ship the decode-and-close change as this quest's first PR. It needs
+  neither [Relay tokens](/quest/m1/auth/relay-refresh.md) nor the
+  per-request lease, so the validator's REGISTER and malformed-token rows
+  need not wait for the rest of the quest.
 - Fallback only: a request the session grant already covers is served
   without verifying its token. Otherwise its token becomes an
   `auth::Request` on the session's `auth::Handle`, the seam an AUTH stream's
@@ -64,7 +85,10 @@ no longer fails the session; this quest gives it meaning.
   verifier; a REQUEST_UPDATE token keeps a subscription alive past the old
   token's expiry; an expired request token ends only that request; with no
   consumer a token-bearing request is refused `Unsupported`; one legacy and
-  one strict draft, Rust and JS.
+  one strict draft, Rust and JS. Regression tests for the decode: a
+  `REGISTER` token on a request closes with `AUTH_TOKEN_CACHE_OVERFLOW`, a
+  `DELETE` or `USE_ALIAS` one with `UNKNOWN_AUTH_TOKEN_ALIAS`, and a
+  malformed request token with `KEY_VALUE_FORMATTING_ERROR`.
 
 Public API: additive on `moq_net::auth::Request` (the request it belongs
 to) and on `moq_auth::Client` (the per-request lease). Wire: none new; the parameter already exists in every supported draft.
diff --git a/quest/m2/README.md b/quest/m2/README.md
index cb552fe1fdd..28897d96bf8 100644
--- a/quest/m2/README.md
+++ b/quest/m2/README.md
@@ -122,4 +122,6 @@ waiting on an upstream release waits in [m4](/quest/m4/README.md).
 - [moq-transport cluster peers](/quest/m2/ietf-cluster-peers.md) - an extended cluster draft lets moq-transport relays peer again, carrying the cluster route layer
 - [MSFTS convergence](/quest/m2/msfts-convergence.md) - the demultiplexed TS lane converges on MSFTS where the two still differ: program tables and the ES payload unit
 - [VAAPI encode and decode](/quest/m2/video-vaapi.md) - H.265 encode and decode, pre-generated bindings, and pooled resize surfaces, including the moq-dev/vaapi release that carries them
+- [Malformed moq-transport input](/quest/m2/ietf-malformed-close.md) - malformed draft-18 and draft-21 control input closes the session with the draft's code, or PROTOCOL_VIOLATION where a code is a real burden and the fallback is recorded in `doc/concept/standard.md`, in moq-net and js/net
+- [moq-transport request codes](/quest/m2/ietf-request-codes.md) - LARGEST_OBJECT, Range Filters (INVALID_FILTER), reserved namespaces, and RENDEZVOUS_TIMEOUT get the draft's answer, or a recorded fallback code, and the deliberate deviations are documented
 - [Dead worklet config](/quest/m2/worklet-dead-config.md) - delete moq-boy's unused worklet plugin and hang's unused `?worker&url` typings
diff --git a/quest/m2/ietf-malformed-close.md b/quest/m2/ietf-malformed-close.md
new file mode 100644
index 00000000000..202bdc7067c
--- /dev/null
+++ b/quest/m2/ietf-malformed-close.md
@@ -0,0 +1,127 @@
+# [L] Malformed moq-transport input closes the session
+
+## Goal
+
+On draft-18 and draft-21, every malformed control input that the draft
+says ends the session does end it, in both `rs/moq-net` and `js/net`.
+It closes with the draft's code, or with PROTOCOL_VIOLATION where a code
+is a real burden and the fallback is recorded in
+`doc/concept/standard.md`. Today moq-net logs most of these and keeps
+going. The cases come from Paul Gregoire's publisher validator
+(github.com/mondain/moq-contribution-interop-runner), run in observed mode
+against a client built on moq-net 0.17.0. Each case below gives the
+runner's scenario name, where it has one:
+
+- An unknown control message type (`receive-unknown-message-type`).
+- A message length that doesn't match its body, or a body cut short by FIN
+  (`d21-message-body-length-mismatch`,
+  `d21-request-message-truncated-at-fin`).
+- A zero-length namespace field, or a namespace or full track name over
+  4096 bytes.
+- A Request ID with the wrong parity: INVALID_REQUEST_ID.
+- A GROUP_ORDER outside 1..2.
+- An understood key-value with a bad serialization:
+  KEY_VALUE_FORMATTING_ERROR
+  (`receive-understood-key-value-invalid-serialization`).
+- A second GOAWAY on the control stream or on a single request stream, or
+  a New Session URI over 8192 bytes: PROTOCOL_VIOLATION. A first GOAWAY on
+  a request stream is legal (draft-18 §10.4, draft-21 §9.2) and leaves the
+  session up.
+- A draft-18 GOAWAY cutoff Request ID with the wrong parity:
+  INVALID_REQUEST_ID, not a redirect.
+- A server SETUP carrying AUTHORITY or PATH: INVALID_AUTHORITY or
+  INVALID_PATH.
+- Repeated unknown or GREASE Setup Options are accepted
+  (`setup-unknown-grease-options-and-duplicates`,
+  `d21-grease-setup-options`). Only a repeated known option is a duplicate.
+- A server SETUP AUTHORIZATION TOKEN that is malformed closes with
+  KEY_VALUE_FORMATTING_ERROR. A REGISTER that overflows our cache (size 0)
+  falls back to USE_VALUE, as draft-21 §9.1.4 requires.
+- A SUBSCRIBE_TRACKS prefix with more than 32 fields or over 4096 bytes
+  closes with PROTOCOL_VIOLATION, instead of being refused per request
+  before it is decoded.
+
+## Plan
+
+Decided with the maintainer on 2026-10-04 and 2026-10-05:
+
+- **Add the missing session codes to the shared registry.**
+  INVALID_REQUEST_ID (0x4), INVALID_PATH (0x8) and INVALID_AUTHORITY
+  (0x19) become `SessionError` variants (`rs/moq-net/src/error.rs`) and
+  `SessionCode` entries (`js/net/src/error.ts`). Their values are the same
+  in drafts 18 and 21. That registry is moq-lite's too, and lite codes
+  below 32 carry moq-transport's meaning, so add the rows to the Session
+  Error Codes table in `drafts/draft-lcurley-moq-lite.md` and to
+  `session_codes_round_trip`. No per-version mapping. Where a code is a
+  real burden, the PROTOCOL_VIOLATION fallback in the Goal applies.
+- **Regression tests, not a CI job for the validator.** Add one session or
+  codec test per case, each failing without its fix and asserting the
+  draft's code, or PROTOCOL_VIOLATION where the fallback is recorded in
+  `doc/concept/standard.md`. Include a positive case: a first GOAWAY on a
+  request stream keeps the session open. Run the external runner once by
+  hand before the PR is marked ready: observed mode,
+  `--publisher-no-fetch`, one scenario per run, on a track of about
+  150 kbps. A full-bitrate track floods the runner's event log and aborts
+  the run.
+- **Mirror in `js/net/src/ietf`** in the same PR.
+- Request tokens are out of scope here. AUTH_TOKEN_CACHE_OVERFLOW and the
+  request-token decode belong to [Request
+  tokens](/quest/m1/auth/request-token.md).
+
+Where each case lives, mapped on 2026-10-04 (paths under
+`rs/moq-net/src/`):
+
+- The SETUP/GOAWAY uni stream runs as a task spawned inline in `run_unis`
+  (`ietf/session.rs`, around lines 751-874). SETUP and SETUP-parameter
+  decode failures there already close the session; only `run_goaway`'s
+  error is just logged. The gated server accept, which reads SETUP early,
+  calls `run_goaway` a second time (`goaway_recv`, around line 375) and
+  does the opposite: any error, even a stream reset, ends the session.
+  Make both sites agree, ideally by filtering inside `run_goaway`. Close
+  on the errors `is_protocol_violation` (`ietf/subscriber.rs`) marks as
+  the peer's fault, not on every error: a reset or transport failure on
+  that stream must stay non-fatal, as `died_before_header` keeps it
+  elsewhere. That fixes the second GOAWAY,
+  the oversize URI, and an unknown type on that stream. On request
+  streams, an error from a follow-up message is only logged at debug in
+  `ietf/publisher.rs` (around line 500); promote decode errors there with
+  the same filter.
+- `died_before_header` (`ietf/session.rs`) treats a body cut short at FIN as
+  the stream dying. A frame whose declared length passes FIN is malformed.
+  Responses decoded at `ietf/publisher.rs` (about lines 1858 and 1937) lack
+  the trailing-bytes check that the first message has.
+- Namespace bounds: `ietf/namespace.rs` checks only the 32-part limit. The
+  track name in `ietf/subscribe.rs` is unbounded.
+- Request ID parity is known only in `Control::new` (`ietf/control.rs`), so
+  thread it to where IDs are decoded.
+- `ietf/group.rs` maps an invalid GROUP_ORDER, or 0, to Descending.
+- KV serialization errors must be told apart from other decode errors.
+  `From<&Error> for SessionError` (`error.rs`) maps every `Decode` error to
+  PROTOCOL_VIOLATION, and `ietf/session.rs` and `ietf/publisher.rs`
+  hard-code it in a few places.
+- GREASE: `ietf/parameters.rs` (around line 122) keys every unknown ID as
+  `Unknown(u64)` in a HashMap, so any repeat fails as `Duplicate`. In this
+  tree that includes the plain duplicate-unknown case the report says now
+  passes, so check which build the report ran.
+- Client SETUP: `decode_peer_setup` (`ietf/session.rs`) ignores AUTHORITY
+  and PATH and never parses the server's token. Reuse `ietf/token.rs`,
+  which already does the server-side fallback.
+- SUBSCRIBE_TRACKS is refused before its prefix is decoded
+  (`ietf/publisher.rs`, about lines 547 and 1609). Decode the prefix first,
+  then refuse.
+
+Test models: `an_unknown_uni_type_closes_the_session` and
+`an_unknown_bidi_type_closes_the_session` in `ietf/session.rs`, which drive
+`ScriptedSession`. Codec tests live in `ietf/parameters.rs` and
+`ietf/subscribe.rs`. Add each new decode error to the `ietf_wire` fuzz
+regressions where it fits.
+
+Public API: new `SessionError` variants and `SessionCode` entries. Wire:
+new moq-lite session codes, with moq-transport's values; moq-transport
+behaviour moves closer to the drafts.
+
+## Related
+
+- [Request tokens](/quest/m1/auth/request-token.md) - owns request-token decode and AUTH_TOKEN_CACHE_OVERFLOW
+- [Request caps](/quest/m0/request-caps.md) - bounds peer lengths and counts; shares the decode paths
+- [moq-transport request codes](/quest/m2/ietf-request-codes.md) - the request-level half of the same validator report
diff --git a/quest/m2/ietf-request-codes.md b/quest/m2/ietf-request-codes.md
new file mode 100644
index 00000000000..4792cbc0cc2
--- /dev/null
+++ b/quest/m2/ietf-request-codes.md
@@ -0,0 +1,67 @@
+# [M] moq-transport requests get the draft's answer
+
+## Goal
+
+On draft-18 and draft-21, `rs/moq-net` and `js/net` answer these requests
+the way the drafts say, without closing the session. Each answer uses the
+draft's code, or an existing code where the exact one costs more than it
+is worth and the fallback is recorded in `doc/concept/standard.md`:
+
+- **LARGEST_OBJECT (0x09) in REQUEST_OK and REQUEST_UPDATE_OK** is
+  accepted. The draft makes it a MUST when objects exist. Today
+  `ietf/request.rs` allows only 0x08 and ACTIVE_COUNT, so a conformant
+  peer's reply closes the session with PROTOCOL_VIOLATION.
+- **Range Filters** get REQUEST_ERROR INVALID_FILTER (0x36), not
+  NOT_SUPPORTED (draft-19 and later). We advertise no MAX_FILTER_RANGES, so
+  the default of 0 applies (draft-21 §9.1.6) and every Range Filter is over
+  the limit. This covers SUBSCRIBE and FETCH alike: both refuse Range
+  Filters today (`ietf/publisher.rs`, around lines 605 and 1292).
+- **Draft-21 reserved namespaces:** draft-21 §2.4.2 and the `.session`
+  rules (§6.5) ask for REQUEST_ERROR DOES_NOT_EXIST, without passing the
+  request to the application, for:
+  - a request for an unrecognized `.session` track or namespace;
+  - a `.session` namespace with an empty track name;
+  - a namespace whose first field is exactly `.`.
+
+  Only these short-circuit. Any other reserved namespace (a first field
+  starting with `.`) still goes to the application, as §2.4.2 requires.
+- **RENDEZVOUS_TIMEOUT:** our wait is capped at 0, which draft-21 §9.20.7
+  allows. If a SUBSCRIBE asks to wait and there is no publisher, it gets
+  TIMEOUT at once. A request that is absent or 0 still gets DOES_NOT_EXIST.
+  This fixes the two quic-zig `rendezvous-timeout` cells in the interop
+  matrix.
+- **OBJECT_DELIVERY_TIMEOUT (0x02) and SUBGROUP_DELIVERY_TIMEOUT (0x06)**
+  on REQUEST_UPDATE are accepted and ignored, as SUBSCRIBE already does
+  (`ietf/subscribe.rs`). Today `ietf/request_stream.rs` refuses both as
+  unsupported.
+
+## Plan
+
+Decided with the maintainer on 2026-10-04 and 2026-10-05:
+
+- **Deliberate deviations stay.** DUPLICATE_SUBSCRIPTION and PREFIX_OVERLAP
+  are never sent, because moq-net deduplicates. OBJECT_DELIVERY_TIMEOUT and
+  SUBGROUP_DELIVERY_TIMEOUT never drop an object or reset a subgroup: they
+  would need wall-clock delivery deadlines, and moq-net's latency
+  enforcement is presentation time only (#2890). The rendezvous wait is
+  capped at 0. Each deviation gets a line under
+  "moq-transport" in `doc/concept/standard.md`, so the next validator run
+  has a reason to point at.
+- **Exact codes when cheap.** INVALID_FILTER becomes a request code. Where
+  one costs more than it is worth, the fallback in the Goal applies.
+- **TIMEOUT, not a timer.** The 0 cap means nothing waits, so no request is
+  ever parked. The reply depends only on whether the parameter asked for a
+  wait. `ietf/subscribe.rs` parses RENDEZVOUS_TIMEOUT and discards it
+  (around line 140); keep it as far as the publisher's track lookup
+  (`ietf/publisher.rs`, around line 617). `Error::Timeout` already maps to
+  TIMEOUT (`ietf/error.rs`).
+- One regression test per case, failing without its fix and asserting the
+  draft's code, or the fallback recorded in `doc/concept/standard.md`.
+  Mirror in `js/net/src/ietf` in the same PR.
+
+Public API: none expected. Wire: none new; replies move closer to the
+drafts.
+
+## Related
+
+- [Malformed moq-transport input](/quest/m2/ietf-malformed-close.md) - the session-level half of the same validator report