feat(moq-audio)!: let publish_capture carry a catalog extension

[Frando]

encode::Producer is already generic over CatalogExt, but Publication and publish_capture hardcode the default, so the turnkey capture path is closed to any consumer whose catalog carries an extension. Reaching it meant driving the capture and the encoder by hand, for no reason other than the signature.

This PR is part of a series to update iroh-live to latest moq, see n0-computer/iroh-live#45. The code and this description were written by Claude Code.

Summary

Threads the parameter through Publication::new, build, Driver, Track and EncoderOutput, which is every type between the entry point and the producer that already had it.

The video side has never had this problem: moq_video::encode::publish_capture takes the catalog producer whole. This brings the audio side level with it.

Breaking changes

Driver becomes Driver<E: CatalogExt = ()>.

The parameter defaults, so nothing that writes Driver in an expression position changes, and no call to Publication::new or publish_capture changes: the extension is inferred from the catalog producer passed in. What breaks is naming the type without the default, which is a struct field, a function signature, or an impl header holding a Driver. Those become Driver<()>.

We hit exactly one such site downstream and it was a one-word change.

Test plan

• cargo check -p moq-audio --all-features and cargo clippy --all-targets, clean.
• cargo test -p moq-audio: 72 pass.
• Used downstream in iroh-live, which publishes a catalog carrying its own extension through publish_capture, which is the case that motivated this.

Note on rebasing

This was written before #3337 reworked Publication to outlive a missing input, and has been re-applied on top of that design rather than merged with the old one: the retry, the Reserved registration and Status::Starting are all upstream's, and this only adds the type parameter to them.

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📥 Commits

Reviewing files that changed from the base of the PR and between 5eea9e3 and f71136a.

📒 Files selected for processing (1)

• rs/moq-audio/src/encode/capture.rs

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Codex Review Summary

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

Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-05T00:31:48.565191Z	f71136a	Draft marked ready

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[kixelated]

@coderabbitai review

(written by Claude Opus 5)

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Tip

For best results, initiate chat on the files or code changes.

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

printf '%s\n' '--- PR metadata ---'
gh pr view 3356 --repo moq-dev/moq --json number,title,baseRefName,headRefName,files,commits

printf '%s\n' '--- Changed files and diff ---'
gh pr diff 3356 --repo moq-dev/moq --color=never

printf '%s\n' '--- Rust source outlines for likely affected files ---'
fd -e rs . | while IFS= read -r file; do
  if rg -q '\b(Publication|Driver|EncoderOutput|publish_capture|CatalogExt)\b' "$file"; then
    echo "### $file"
    ast-grep outline "$file" --items all --type struct,impl,function,type --match 'Publication|Driver|EncoderOutput|publish_capture|CatalogExt' || true
  fi
done

Length of output: 11673

---

🏁 Script executed:

#!/bin/bash
set -euo pipefail

printf '%s\n' '--- capture publication and driver paths ---'
sed -n '160,390p' rs/moq-audio/src/encode/capture.rs
sed -n '390,735p' rs/moq-audio/src/encode/capture.rs
sed -n '780,900p' rs/moq-audio/src/encode/capture.rs

printf '%s\n' '--- audio producer and reservation definitions ---'
sed -n '1,280p' rs/moq-audio/src/encode/producer.rs

printf '%s\n' '--- Catalog extension trait and catalog producer ---'
sed -n '1,240p' rs/moq-mux/src/catalog/hang/ext.rs
sed -n '1,240p' rs/moq-mux/src/catalog/producer.rs

printf '%s\n' '--- Public API uses and type annotations ---'
rg -n --type rust -C 4 \
  '\b(Publication::new|publish_capture\s*\(|Driver(?:\s*<[^>]*>)?\b)' \
  rs

printf '%s\n' '--- Generic catalog producer construction and audio/video capture parity ---'
rg -n --type rust -C 4 \
  '\bmoq_mux::catalog::Producer(?:\s*<[^>]*>)?\b|\bpublish_capture\s*\(' \
  rs/moq-audio rs/moq-video rs/moq-cli

Length of output: 110611

---

@kixelated No issues found.

The CatalogExt type parameter is preserved from Publication::new and publish_capture through Driver, Track, Reserved, Producer, and EncoderOutput. Existing callers retain the default Driver<()> behavior.

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