diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ed2d55c
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,3 @@
+target/
+node_modules/
+.worktrees/
\ No newline at end of file
diff --git a/.opencode/agents/implementation-specialist.md b/.opencode/agents/implementation-specialist.md
index 62b5216..746c7e2 100644
--- a/.opencode/agents/implementation-specialist.md
+++ b/.opencode/agents/implementation-specialist.md
@@ -210,55 +210,101 @@ This is especially important for complex tasks that span many file operations.
 Read `AGENTS.md` at project root for full details. Key rules:
 
 1. **No comments in code** — Per project convention. Doc comments (`///`, `//!`)
-   are fine and expected on public API.
-2. **Error handling** — `thiserror` for library error types. No panics in
-   library code. No `unwrap()` or `expect()` outside tests. For poisoned
-   `RwLock`/`Mutex`, use `unwrap_or_else(|e| e.into_inner())` so a panic in one
-   operation does not cascade to other operations.
-3. **`tokio` is the async runtime** — all I/O is async. Use `tokio::sync`
-   primitives (`oneshot`, `mpsc`) for request correlation and subscription
-   channels; `parking_lot` for short-held internal locks (`PendingRequestMap`).
-4. **No secret material on the wire** — `call.requested`/`call.responded`
-   payloads and `OperationContext.metadata` carry no private keys, API keys, or
-   decrypted credentials. Outbound credentials flow through `Capabilities`
-   injected at the assembly layer → `HandlerRegistration.capabilities` →
-   `OperationContext.capabilities` → handler.
-5. **No-env-vars invariant** — no handler reads outbound credentials from any
-   source other than `OperationContext.capabilities`. This is a spec-level
-   invariant, not a runtime convention.
-6. **`OperationEnv` must remain a trait** — the trait-based design enables
-   registry layering (session overlays, connection overlays, peer-keyed
-   composition). Do not make it concrete or hardcode the global registry.
-7. **Wire formats are stable** — `EventEnvelope` (`{ type, id, payload }` +
-   length-prefixed JSON framing) and the channels 8-byte chunk header
-   (`[channel_id:u32 BE][length:u32 BE][payload]`) are one-way doors. New event
-   types may be added; existing shapes must not change.
-8. **Producer/consumer, not server/client** — both sides of a call or channels
-   connection can initiate. Use "producer"/"consumer" or "accept side"/"connect
-   side," not "server"/"client."
-9. **Vendored core types** — `Connection`, `ProtocolHandler`, `BiStream`,
-   `BidiStreamSource`, `AuthContext`, `IdentityProvider`, `Identity`,
-   `AuthToken`, `Capabilities`, `OwnershipProvider`, `HandlerError`,
-   `StreamError` live in this crate. Do not add a separate `alkcore` dependency.
-   Keep them lean (no TLS, no transport coupling, no endpoint/accept-loop).
-10. **`alktype` dependency** — use `alktype` for binary layout (channels chunk
-    header, future binary payload schemas) and JSON payload schema validation
-    (`OperationSpec`'s `input_schema`/`output_schema`). Do not roll your own.
-11. **Feature flags** — transports may be feature-gated if the need arises. The
-    base crate should compile lean (no `quinn`, no `iroh` unless the feature is
-    on). Verify both `cargo test` (default) and `cargo test --all-features` pass
-    if features are added.
-12. **Abort cascades to descendants** — `call.aborted` for a parent cascades to
-    all non-terminal descendants. Default `abort-dependents`;
-    `continue-running` opt-in. The composing handler decides the child's policy,
-    not the wire caller.
-13. **Peer authorization via `AccessControl`** — a remote peer's call is
-    authorized by `AccessControl::check(peer_identity)`. No `remote_safe` flag,
-    no `trusted_peer` bypass. `Visibility::Internal` ops are never wire-callable.
-14. **Naming conventions** — Rust standard: `snake_case` for functions/variables/
-    modules, `PascalCase` for types/traits, `SCREAMING_SNAKE_CASE` for constants.
-15. **Module structure** — one module per file under `src/`, re-exported from
-    `src/lib.rs`. Public API surface is `lib.rs` re-exports.
+   are fine and expected on public API. Inline `//` comments only when the user
+   asks or when a non-obvious safety/correctness constraint would otherwise be
+   missed (e.g., "zero-length stdin is the EOF sentinel — the codec does not
+   special-case it; the adapter interprets `length == 0` chunks").
+2. **Error handling** — `thiserror` for library error types (`TtyError`,
+   `NegotiateError`, `WireError`; `HandlerError`/`StreamError` come from
+   alkcall::core). No panics in library code. No `unwrap()` or `expect()`
+   outside tests. For poisoned `RwLock`/`Mutex`, use
+   `unwrap_or_else(|e| e.into_inner())`.
+3. **`tokio` is the async runtime** — all I/O is async. The adapter's
+   per-session pumps, the channels integration, and `TtySession` are all async.
+   Use `tokio::sync` primitives (`oneshot`, `mpsc`) for request/exit
+   correlation and stdout/stderr streams. The PTY bridge in `src/local/pty.rs`
+   is the one exception: three dedicated std threads feeding tokio mpsc/oneshot
+   channels (the `portable_pty` API is blocking) — behind the `local` feature.
+4. **WASM target is load-bearing** — the default crate (no `local` feature)
+   MUST compile to `wasm32-unknown-unknown`. This is what makes the downstream
+   TS/Python adapter story work. `Cargo.toml` uses
+   `tokio = { default-features = false, features = ["rt", "sync", "io-util", "macros"] }`
+   (the wasm-clean subset alkcall uses); `local` adds `tokio/process` +
+   `tokio/rt-multi-thread`. **Do NOT use `features = ["full"]`** — it pulls in
+   `signal`/`fs`/`net` which break `wasm32-unknown-unknown`. The adapter's
+   `tokio::spawn` is fine on wasm; the `local` module's std threads,
+   `tokio::process::Command`, and `libc::kill` are the non-wasm parts, and
+   they're feature-gated.
+5. **Wire formats are stable** — two one-way doors:
+   - **5-byte chunk header** (`[stream_type: u8][length: u32 BE][payload]`) —
+     the raw chunk codec in `wire.rs`. Five stream types: `STREAM_STDIN=0`,
+     `STREAM_STDOUT=1`, `STREAM_STDERR=2`, `STREAM_CTRL_IN=3`,
+     `STREAM_CTRL_OUT=4`. Zero-length data chunks are sentinels (zero-length
+     stdin = EOF from client; zero-length stdout = "drained" from server);
+     control chunks are never zero-length. Changing the header, the
+     stream-type values, or the sentinel semantics breaks all peers.
+   - **Negotiation frame** (4-byte BE length prefix + UTF-8 JSON
+     `NegotiateRequest` body) — self-contained, not reused from alkcall's
+     `EventEnvelope` framing. The `NegotiateRequest` JSON shape is
+     wire-stable once consumers exist.
+   Per ADR-093: TTY always uses its 5-byte format, even inside channels. The
+   channels layer strips its 8-byte header transparently — the same `wire.rs`
+   code runs in both direct (`alk/tty`) and channels (`alk/channels`) modes;
+   only the `BiStream` source differs.
+6. **`TtyBackend` trait shape is a one-way door** — the trait in
+   `src/backend.rs` is the inversion point between the wire-format adapter and
+   the backend crates (alktty's own `local` feature module, future
+   `alknet-docker`, `alknet-ssh`). alktty defines the trait; the backends
+   implement it. The adapter holds a `HashMap<String, Arc<dyn TtyBackend>>`
+   keyed by the negotiation frame's `backend` string; backends produce
+   `TtyHandle`s, they do not write to the wire. `TtyError` is
+   `#[non_exhaustive]` so new variants are additive.
+7. **Producer/consumer, not server/client** — both sides of a `alk/tty` or
+   `alk/channels` connection can initiate. Use "producer"/"consumer" or
+   "accept side"/"connect side," not "server"/"client."
+8. **`local` feature isolation** — the `local` module is the only non-wasm
+   part of the crate. The shared/producer/consumer modules (`wire`, `control`,
+   `negotiation`, `backend`, `adapter`, `channels`, `session`) MUST NOT import
+   from `crate::local` or reference any `local`-only type (`LocalTtyBackend`,
+   `portable_pty`, `tokio::process::Command`). The local backend is injected at
+   the assembly layer, not wired in by the adapter. A regression where a
+   non-`local` module pulls in `portable_pty`, `tokio::process`,
+   `std::thread`, or `libc` (outside the existing `cfg(unix)` calls in
+   `control.rs`/`pipe.rs`) silently breaks the downstream TS/Python adapter
+   story.
+9. **Module structure** — one module per file under `src/`, re-exported from
+   `src/lib.rs`. Producer half: `src/adapter.rs` + `src/channels.rs`. Consumer
+   half: `src/session.rs`. Shared: `src/wire.rs`, `src/control.rs`,
+   `src/negotiation.rs`, `src/backend.rs`. The `src/local/` module is behind
+   the `local` feature and never imported from the shared/producer/consumer
+   modules — only re-exported from `lib.rs` under `#[cfg(feature = "local")]`.
+10. **BAST document, not alktype dependency** — `docs/architecture/tty-bast.md`
+    (Phase 4, not yet written) will be the machine-readable spec for the
+    `alk/tty` wire format, conforming to the BAST meta-schema at
+    `https://alk.dev/bast/v1/schema`. alktty does **not** depend on alktype;
+    the hand-rolled `ChunkReader`/`ChunkWriter` in `wire.rs` is the runtime
+    codec, the BAST document is the human-readable contract. If runtime
+    validation against the BAST becomes desirable later, alktype becomes an
+    optional dep — do not roll your own offset map or validator for complex
+    formats.
+11. **Feature flags** — the only feature is `local` (default = `[]`). `local`
+    is inherently non-wasm; enabling it on wasm is a build error by design.
+    Verify both `cargo test` (default) and `cargo test --all-features` pass.
+    Do not add a feature flag that pulls non-wasm deps into the default crate.
+12. **Access control** — the direct-ALPN path keeps the ad-hoc scope check
+    (`has_scope(identity, TTY_OPEN_SCOPE)`) and optionally consults
+    `OwnershipProvider` (`provider.owns(id_ref, kind, &id, "tty")` — the 4-arg
+    shape). The channels path gets both for free via
+    `ChannelCore::register_openable`, which wires `AccessControl` into the
+    operation spec. `OwnershipStore::record(&self, identity, resource_type,
+    resource_id)` is the 3-arg shape (alkcall dropped the old `action` arg).
+13. **Naming conventions** — Rust standard: `snake_case` for functions/variables/
+    modules, `PascalCase` for types/traits, `SCREAMING_SNAKE_CASE` for
+    constants (`STREAM_STDIN`, `TTY_OPEN_SCOPE`, `CHUNK_HEADER_LEN`).
+14. **No `unsafe`** — the crate has zero `unsafe` blocks. The PTY bridge's
+    `libc::kill(-pgid, sig)` and `libc::kill(pid, sig)` calls are safe `libc`
+    crate APIs (not `unsafe` blocks in this crate). Do not introduce `unsafe`
+    for performance.
 
 ## Key Principles
 
diff --git a/AGENTS.md b/AGENTS.md
new file mode 100644
index 0000000..805e20b
--- /dev/null
+++ b/AGENTS.md
@@ -0,0 +1,292 @@
+# AGENTS.md
+
+Operating instructions for opencode agents working in this repo. opencode
+auto-loads this file as instructions, overriding the built-in defaults for
+this project. Custom agents in `.opencode/agents/` inherit these rules
+unless their own prompts say otherwise.
+
+## Git Workflow
+
+**Commit and push when reasonable.** When a change is complete and
+verified (build + lint + tests pass), commit and push to `origin/main`
+without asking. This overrides the built-in default of "only commit when
+explicitly asked."
+
+The workflow:
+
+1. Make the change
+2. Verify: `cargo test`, `cargo clippy --all-targets -- -D warnings`,
+   `cargo fmt --check`, `cargo doc --no-deps` if docs changed
+3. Inspect `git status` and `git diff` before staging — stage only the
+   intended files, never secrets
+4. Write a concise commit message matching the repo style (see `git log
+   --oneline -10`). For multi-point changes, use a summary line plus a
+   body with bullet points and a verification block.
+5. `git push origin main`
+6. Report the commit hash and the verification summary
+
+Exceptions — **do not** commit or push without asking:
+
+- The change is exploratory / speculative (you're not sure the user wants
+  it kept)
+- The user is actively reviewing the diff and may ask for changes
+- The change touches the wire format or the `TtyBackend` trait shape
+  (one-way doors — see "Wire formats are stable" and "`TtyBackend` trait
+  shape is a one-way door" below; the 5-byte chunk header, the
+  negotiation-frame layout, the `NegotiateRequest` JSON shape, and the
+  trait signature are wire-stable contracts once consumers exist)
+- You'd be force-pushing, amending a published commit, creating an empty
+  commit, or skipping hooks
+
+Never commit secrets, keys, or credentials. If a commit fails or hooks
+reject it, fix the issue and create a new commit — do not amend the
+failed one.
+
+Git identity is preconfigured (`glm-5.2 <glm-5.2@alk.dev>`). Do not
+change `git config`, skip hooks, or use `git commit -i`.
+
+## Project Conventions (Rust / TTY protocol crate)
+
+This is the `alk/tty` terminal-session protocol crate — a
+producer/consumer protocol crate on top of alkcall channels. It folds
+the old `alknet-tty` (wire/adapter/backend-trait half) and
+`alknet-tty-local` (`portable_pty` + `tokio::process` half) from the
+alknet mono-repo into a single crate with a `local` feature. The
+conventions below apply to all work in `src/` and `tests/`. They mirror
+`.opencode/agents/implementation-specialist.md` §Project Conventions
+and are repeated here so they apply to every session, not just spawned
+implementation agents.
+
+1. **No comments in code** unless the user explicitly asks. This is a
+   project-wide convention. Doc comments (`///`, `//!`) are fine and
+   expected on public API. Inline `//` comments only when the user asks
+   or when a non-obvious safety/correctness constraint would otherwise be
+   missed (e.g., "zero-length stdin is the EOF sentinel — the codec does
+   not special-case it; the adapter interprets `length == 0` chunks").
+
+2. **Error handling** — `thiserror` for library error types
+   (`TtyError`, `NegotiateError`, `WireError`, `HandlerError`/`StreamError`
+   come from alkcall::core). No panics in library code. No `unwrap()` or
+   `expect()` outside tests. If you reach for `unwrap`, the error path
+   wasn't specified — stop and decide what should actually happen. For
+   poisoned `RwLock`/`Mutex`, use
+   `unwrap_or_else(|e| e.into_inner())` so a panic in one operation does
+   not cascade to other operations.
+
+3. **`tokio` is the async runtime** — all I/O is async. The adapter's
+   per-session pumps, the channels integration, and `TtySession` are all
+   async. Use `tokio::sync` primitives (`oneshot`, `mpsc`) for
+   request/exit correlation and stdout/stderr streams. The PTY bridge in
+   `src/local/pty.rs` is the one exception: it uses three dedicated std
+   threads feeding tokio mpsc/oneshot channels (the `portable_pty` API
+   is blocking) — and it's behind the `local` feature.
+
+4. **WASM target is load-bearing** — the default crate (no `local`
+   feature) MUST compile to `wasm32-unknown-unknown`. This is what makes
+   the downstream TS/Python adapter story work (a wasm-compiled alktty
+   is the protocol layer for a sandboxed adapter). `Cargo.toml` uses
+   `tokio = { default-features = false, features = ["rt", "sync",
+   "io-util", "macros"] }` (the wasm-clean subset alkcall uses) and
+   `local` adds `tokio/process` + `tokio/rt-multi-thread`. **Do NOT use
+   `features = ["full"]`** — it pulls in `signal`/`fs`/`net` which break
+   `wasm32-unknown-unknown`. The adapter's `tokio::spawn` for per-session
+   pumps is fine on wasm (the wasm tokio runtime supports `spawn`); the
+   `local` module's std threads, `tokio::process::Command`, and
+   `libc::kill` are the non-wasm parts, and they're feature-gated.
+   `libc` stays under `cfg(unix)` (it's already there for
+   `signal_from_name` and the pipe-mode `kill` path — neither runs on
+   wasm because the only callers are in `local`).
+
+5. **Wire formats are stable** — two wire formats live in this crate,
+   both one-way doors:
+   - **5-byte chunk header** (`[stream_type: u8][length: u32 BE]
+     [payload]`) — the raw chunk codec in `wire.rs`. Five stream types:
+     `STREAM_STDIN=0`, `STREAM_STDOUT=1`, `STREAM_STDERR=2`,
+     `STREAM_CTRL_IN=3`, `STREAM_CTRL_OUT=4`. Zero-length data chunks are
+     sentinels (zero-length stdin = EOF from client; zero-length stdout
+     = "drained" from server); control chunks are never zero-length.
+     Changing the header, the stream-type values, or the sentinel
+     semantics breaks all peers. See ADR-052 (ported as alktty ADR-001).
+   - **Negotiation frame** (4-byte BE length prefix + UTF-8 JSON
+     `NegotiateRequest` body) — self-contained per ADR-057 (ported as
+     alktty ADR-008), not reused from alkcall's `EventEnvelope` framing
+     (the payload is `NegotiateRequest`, not `EventEnvelope`; alkcall's
+     `FrameFramedReader` is hardcoded to deserialize `EventEnvelope`).
+     The `NegotiateRequest` JSON shape is wire-stable once consumers
+     exist.
+
+   Per ADR-093 (ported as alktty ADR-007): TTY always uses its 5-byte
+   format, even inside channels. The channels layer strips its 8-byte
+   header and hands TTY the payload transparently — the same `wire.rs`
+   code runs in both direct (`alk/tty`) and channels (`alk/channels`)
+   modes; only the `BiStream` source differs.
+
+6. **`TtyBackend` trait shape is a one-way door** — the trait
+   (`src/backend.rs`) is the inversion point between the wire-format
+   adapter and the backend crates (alktty's own `local` feature module,
+   future `alknet-docker`, `alknet-ssh`). alktty defines the trait; the
+   backends implement it. Changing the trait shape after backends exist
+   is a rewrite across crates. The adapter holds a
+   `HashMap<String, Arc<dyn TtyBackend>>` keyed by the negotiation
+   frame's `backend` string and pumps the `TtyHandle` fields
+   bidirectionally; backends produce handles, they do not write to the
+   wire. `TtyError` is `#[non_exhaustive]` so new variants are additive
+   (two-way-door extension within the one-way trait shape). See ADR-053
+   (ported as alktty ADR-002).
+
+7. **Producer/consumer, not server/client** — inherited from alkcall.
+   Both sides of a `alk/tty` or `alk/channels` connection can initiate.
+   A producer exposes TTY (direct ALPN via `TtyAdapter::ProtocolHandler`,
+   or via `channels::register_openable`); a consumer opens a session
+   (`TtySession::connect_direct` / `open_via_channels`). Both sides can
+   be both simultaneously — connection direction (who opened it) is
+   independent of TTY direction (who's the shell, who's the client).
+   Avoid "server" and "client" framing in docs and API names; use
+   "producer" and "consumer," or "accept side" / "connect side" for the
+   connection-establishment half specifically.
+
+8. **Module structure** — one module per file under `src/`, re-exported
+   from `src/lib.rs`. Public API surface is `lib.rs` re-exports. The
+   crate has three concerns:
+   - **Producer half** — `src/adapter.rs` (`TtyAdapter` + `drive_session`
+     for direct `alk/tty`) and `src/channels.rs` (`register_openable`
+     helper + `TtyOpenHandler` for the `alk/channels` multiplexed path).
+   - **Consumer half** — `src/session.rs` (`TtySession` typed client
+     with `connect_direct` and `open_via_channels` constructors).
+   - **Shared** — `src/wire.rs` (chunk codec), `src/control.rs`
+     (control-message enum + `signal_from_name`), `src/negotiation.rs`
+     (negotiation frame + `NegotiateRequest`), `src/backend.rs`
+     (`TtyBackend` trait, `TtyHandle`, `TtyParams`, `TtyError`).
+   The `src/local/` module (the folded `alknet-tty-local`) is behind the
+   `local` feature and never imported from the shared/producer/consumer
+   modules — only re-exported from `lib.rs` under
+   `#[cfg(feature = "local")]`.
+
+9. **`local` feature isolation** — the `local` module is the only
+   non-wasm part of the crate. The shared/producer/consumer modules
+   (`wire`, `control`, `negotiation`, `backend`, `adapter`, `channels`,
+   `session`) MUST NOT import from `crate::local` or reference any
+   `local`-only type (`LocalTtyBackend`, `portable_pty`,
+   `tokio::process::Command`). The producer's `TtyAdapter` takes a
+   `HashMap<String, Arc<dyn TtyBackend>>` — the local backend is
+   injected at the assembly layer, not wired in by the adapter. A
+   regression where a non-`local` module pulls in `portable_pty`,
+   `tokio::process`, `std::thread`, or `libc` (outside the existing
+   `cfg(unix)` calls in `control.rs`/`pipe.rs`) silently breaks the
+   downstream TS/Python adapter story.
+
+10. **BAST document for the wire format** — `docs/architecture/tty-bast.md`
+    (Phase 4, not yet written) will be the machine-readable spec for the
+    `alk/tty` wire format, conforming to the BAST meta-schema at
+    `https://alk.dev/bast/v1/schema`. BAST is plain JSON — no
+    dependency required to author or consume it. alktty does **not**
+    depend on alktype; the hand-rolled `ChunkReader`/`ChunkWriter` in
+    `wire.rs` is the runtime codec, the BAST document is the
+    human-readable contract that describes what those types round-trip.
+    If runtime validation against the BAST becomes desirable later,
+    alktype becomes an optional dep and the BAST document is already
+    there to feed it. Do not roll your own offset map or validator for
+    complex formats — use alktype (as an optional dep) when that
+    surfaces.
+
+11. **Access control** — the producer's direct-ALPN path keeps the
+    existing ad-hoc scope check (`has_scope(identity, TTY_OPEN_SCOPE)`)
+    for the scope gate and optionally consults `OwnershipProvider` for
+    the resource-ownership check (`provider.owns(id_ref, kind, &id,
+    "tty")` — the 4-arg shape alkcall adopted). The channels path gets
+    both for free via `ChannelCore::register_openable`, which wires
+    `AccessControl` into the operation spec — the registry runs the ACL
+    before the wrapper, so the `OpenHandler` only needs to validate
+    params and spawn the protocol. Terminal sessions are resources per
+    ADR-050 (ported as alktty ADR-003); `OwnershipStore::record(&self,
+    identity, resource_type, resource_id)` is the 3-arg shape (alkcall
+    dropped the old `action` arg).
+
+12. **Feature flags** — the only feature is `local` (default = `[]`).
+    `local` is inherently non-wasm (`portable-pty` + `tokio::process`
+    need a real OS); enabling `local` on wasm is a build error by
+    design. Verify both `cargo test` (default) and
+    `cargo test --all-features` pass. Do not add a feature flag that
+    pulls non-wasm deps into the default crate.
+
+13. **Naming** — Rust standard: `snake_case` for functions/variables/
+    modules, `PascalCase` for types/traits, `SCREAMING_SNAKE_CASE` for
+    constants (`STREAM_STDIN`, `TTY_OPEN_SCOPE`, `CHUNK_HEADER_LEN`).
+
+14. **No `unsafe`** — the crate has zero `unsafe` blocks. The PTY
+    bridge's `libc::kill(-pgid, sig)` and `libc::kill(pid, sig)` calls
+    are safe `libc` crate APIs (not `unsafe` blocks in this crate);
+    bounds-checked slice access via `get(..)`/`ok_or_else` is the
+    pattern. Do not introduce `unsafe` for performance.
+
+## Verification Commands
+
+Run these before committing. All must pass.
+
+```bash
+cargo test
+cargo clippy --all-targets -- -D warnings
+cargo fmt --check
+cargo doc --no-deps
+cargo test --all-features
+cargo check --target wasm32-unknown-unknown       # the default crate stays wasm-clean
+cargo clippy --target wasm32-unknown-unknown -- -D warnings
+cargo publish --dry-run --allow-dirty             # before a release
+```
+
+The wasm check is the structural guard for the "default crate is
+wasm-clean" invariant — run it whenever a non-`local` module changes.
+`cargo test --all-features` exercises the `local` backend (PTY mode is
+`#[cfg(unix)]`; pipe mode is cross-platform).
+
+## Architecture Context
+
+- `docs/plans/project-setup.md` — the current plan (phases 0–5). Phase 0
+  (scaffold hygiene), Phase 1 (port core types), Phase 2 (channels
+  integration + `TtySession`), and Phase 3 (`local` backend) are landed.
+  Phase 4 (architecture docs + BAST schema + renumbered ADRs) and
+  Phase 5 (tests, including integration tests in `tests/` at the crate
+  root) are not yet done.
+- `docs/architecture/` does not exist yet — it's created in Phase 4.
+  The ADRs referenced below (alknet ADR-052, 053, 054, 055, 056, 057,
+  077, 093) will be ported and renumbered into alktty's ADR range
+  (001..008) at that time. Until then, the alknet originals at
+  `/workspace/@alkdev/alknet/docs/architecture/decisions/` are the
+  authoritative source — read them before non-trivial changes to the
+  wire format, trait, or adapter.
+- Key ADRs that inform this crate's design (alknet numbers → planned
+  alktty numbers):
+  - ADR-052 → 001 — two-carriage wire format (JSON negotiation + raw
+    chunks); the 5-byte chunk header
+  - ADR-053 → 002 — `TtyBackend` trait (the inversion point between
+    wire-format adapter and backend crates)
+  - ADR-050 → 003 — dynamic resource ownership for runtime-spawned
+    terminal sessions
+  - ADR-054 → 004 — single crate with `local` feature (resolves the
+    alknet cyclic-dep workaround; the local backend is folded in)
+  - ADR-055 → 005 — exit-code reporting (`{"type":"exit","code":N}` on
+    `ctrl_out`; `code: -1` on wait-failure)
+  - ADR-056 → 006 — control-message split (`ctrl_in` client→server,
+    `ctrl_out` server→client; the bidirectionality fix)
+  - ADR-093 → 007 — TTY always uses its 5-byte format inside channels
+    (reverses ADR-077; channels strips its 8-byte header transparently)
+  - ADR-057 → 008 — negotiation framing is self-contained (not reused
+    from alkcall's `EventEnvelope` framing)
+- If a TODO references a "Phase 7" note or a design direction that an
+  ADR has since decided against, the TODO is stale — remove it and
+  align with the ADR. Do not implement the rejected design.
+- The crate was ported from `/workspace/@alkdev/alknet/crates/
+  alknet-tty/src/` (wire, control, negotiation, backend, adapter) and
+  `/workspace/@alkdev/alknet/crates/alknet-tty-local/src/` (local
+  backend, pty, pipe). The source architecture docs at
+  `/workspace/@alkdev/alknet/docs/architecture/crates/tty/` are the
+  port origin for the Phase 4 spec docs.
+- alkcall (`/workspace/@alkdev/alkcall`) is the upstream dependency.
+  All types formerly in `alknet-core` (`Connection`, `ProtocolHandler`,
+  `BiStream`, `BidiStreamSource`, `AuthContext`, `Identity`,
+  `IdentityProvider`, `AccessControl`, `OwnershipProvider`,
+  `OwnershipStore`, `InMemoryOwnershipStore`, `HandlerError`,
+  `StreamError`) come from `alkcall::core`. alkcall is v0.1.x —
+  breaking changes are expected at this major-zero stage; this is the
+  first real consumer, so we find and fix issues upstream rather than
+  working around them. Pin `alkcall = "0.1.1"` and bump deliberately.
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