[dezren39]

Slice B of the landed #787 design (doc/2026-11-01_design_id787.md §4.2 and §6 row B).

Part of #787. This is one of six slices and does not close the issue; C–F remain.

What this adds

A new, inert Rust module pkgs/id/src/input_framing.rs (plus its registration in
src/lib.rs) that turns arbitrary transport chunks into complete logical key tokens:

• Retains an incomplete UTF-8 scalar, CSI or SS3 sequence across push calls and
  emits one token per complete key, independent of how the transport split the bytes.
  Plain text emits one token per Unicode scalar.
• Token bytes are never rewritten; what the assembler emits is exactly what the
  transport received, so the durable Input(Vec<u8>) boundary is untouched.
• Bounds: 256-byte cap per pending token and a 5-second incomplete-token deadline
  (§4.2 safety defaults). Overlong tokens, invalid UTF-8, incomplete tokens at
  EOF/deadline and queue loss are fatal; the caller must close the session, because
  a missing prefix cannot be resynchronised.
• Connection-local state: one InputAssembler per raw connection, so interleaved
  connections cannot mix partial tokens.
• ReplyFilter seam only: push_filtered drops recognized control replies while
  preserving key order, for F13.4's demultiplexer to implement in slice E. No filter
  is provided that swallows unrecognized keys.

No activation. world_ssh does not call the module, the durable Input event,
journal format, guest ABI, browser encoder and lease/negotiation paths are unchanged.

Tests

cd pkgs/id && cargo test --lib input_framing::tests
# 16 passed; 0 failed

Coverage follows the §6 done check: every split point and byte boundary of the fixture
corpus, coalesced keys, split probe-reply + key order, cap boundary (exactly 256 passes,
257 fails), unterminated over-cap, deadline, EOF with/without pending bytes, invalid
UTF-8 and overlong forms, malformed escapes, queue loss and interleaved connections.

cargo fmt --all -- --check passes. Default-feature targeted crate tests pass (16/16),
and cargo check --all-targets passes with the crate's default features. The isolated
module also passes clippy-driver with the crate's Clippy groups and repo-specific
allow-list. Both cargo clippy --lib and cargo clippy --lib --all-features could not
complete: they failed with E0514 incompatible-compiler metadata errors in existing
dependency artifacts (e.g. p2panda_core, thiserror, anyhow) before reaching the
crate lint pass. cargo check --all-targets --all-features also cannot compile in this
checkout because the RustEmbed input web/dist has not been generated. The
--no-default-features test variant cannot compile on current main because of
pre-existing world/petname feature-gated references in chat.rs/invite.rs; the
default-feature test variant passed.

No automated CI jobs were triggered for this PR. .github/workflows/id-check.yml has
only schedule and workflow_dispatch triggers (its header still mentions PRs), so
package-level PR CI coverage is absent on this branch; the required code check was run
locally as described above. roc-test passes all 83 Roc expectations.

Slice status after this PR

• A — merged (feat(id): add kitty-disambiguate-v1 key decoding #4438)
• B — this PR (inert)
• C (browser encoder) and D (parity oracle) — next, independent/inert
• E/F — still gated on F13.4 detection (id: Phase 13 F13.4 presentation capability tiers with in-band terminal detection #786)

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Reviewing files that changed from the base of the PR and between 329b23b and 24a57d5.

Files selected for processing: 2

• pkgs/id/src/input_framing.rs
• pkgs/id/src/lib.rs

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[chatgpt-codex-connector]

Codex Review Summary

This comment shows the latest Codex review activity on this pull request.

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-11-04T14:46:51.364068Z	fcc276a	PR opened

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[chatgpt-codex-connector]

💡 Codex Review

Here are some automated review suggestions for this pull request.

Reviewed commit: fcc276a709

ℹ️ About Codex in GitHub

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[chatgpt-codex-connector]

Prefix the new test names with test_

All 16 new test functions omit the test_ prefix explicitly required by the scoped naming convention in pkgs/id/AGENTS.md. Rename these functions to follow that documented convention; the same correction applies throughout this test module.

AGENTS.md reference: pkgs/id/AGENTS.md:L140-L140

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