fix(watch): preserve shorthand requirements when resolving watched sources #18

Summary

When a source is already watched, add <source>@branch:other matches its watch record and installs the watched baseline, silently ignoring the typed branch requirement. The equivalent --branch other flag is rejected. The same user intent therefore has different behavior depending on syntax.

Code evidence at 5d4987b:

• Sources/Core/RuntimeService.swift:235 routes ordinary adds through resolveSourceOrWatch.
• Sources/Core/WatchLedger.swift:737 parses the input but compares only source identity when matching a watch.
• Sources/Core/RuntimeService.swift:782 selects the watch before normal source resolution; :786 checks only the separate requirement argument used by flags.
• Sources/Core/RuntimeService.swift:797 chooses the watch baseline/reviewed commit, and :815 reconstructs source data from the watch rather than the input selectors.

Reproduction

Executed at 5d4987b.

Run in Bash after cd "<checkout>" && swift build, replacing <checkout> with the absolute path of the checkout at this revision. Use a fresh reproduction directory. The commands isolate HOME, agent configuration, and XDG_*, and remove their fixture root on exit.

set -eu
checkout="<checkout>"
skill_bin="$checkout/.build/debug/skill"
repro_root="$checkout/.build/issue-repro-watch-routing"
mkdir -p "$repro_root/home" "$repro_root/tmp" "$repro_root/project"
trap 'rm -rf "$repro_root"' EXIT
isolated() {
  env -i PATH="$PATH" HOME="$repro_root/home" \
    CODEX_HOME="$repro_root/home/.codex" \
    CLAUDE_CONFIG_DIR="$repro_root/home/.claude" \
    XDG_CONFIG_HOME="$repro_root/home/.config" \
    XDG_STATE_HOME="$repro_root/home/.local/state" \
    XDG_CACHE_HOME="$repro_root/home/.cache" TMPDIR="$repro_root/tmp" \
    GIT_CONFIG_NOSYSTEM=1 GIT_CONFIG_GLOBAL=/dev/null \
    GIT_AUTHOR_NAME=Fixture [email protected] \
    GIT_COMMITTER_NAME=Fixture [email protected] \
    "$@"
}
skill() { isolated "$skill_bin" "$@"; }
write_skill() {
  mkdir -p "$1"
  printf -- '---\nname: %s\ndescription: Reproduction fixture\n---\n%s\n' "$2" "$3" > "$1/SKILL.md"
}
cd "$repro_root/project"

write_skill "$repro_root/source/skills/demo" demo watched-main
isolated git init -q -b main "$repro_root/source"
isolated git -C "$repro_root/source" add .
isolated git -C "$repro_root/source" commit -qm main
isolated git -C "$repro_root/source" checkout -qb other
write_skill "$repro_root/source/skills/demo" demo requested-other
isolated git -C "$repro_root/source" add .
isolated git -C "$repro_root/source" commit -qm other
isolated git -C "$repro_root/source" checkout -q main
skill add "$repro_root/source" --branch main --watch-only --skill demo --agent codex
skill add "$repro_root/source@branch:other" --skill demo --agent codex --mode copy
printf 'installed content: '
tail -1 .agents/skills/demo/SKILL.md
set +e
skill add "$repro_root/source" --branch other --skill demo --agent codex --mode copy
printf 'flag form exit: %s\n' "$?"

Observed output (relevant lines; temporary paths shortened to <temp>):

watched source path skills/demo
installed demo for codex at <temp>/project/.agents/skills/demo
installed content: watched-main
Error: Invalid source: source requirement flags cannot be used with a watch source
flag form exit: 1

Expected Behavior

Parse and validate requirement intent before choosing the watch/source route. A requirement supplied in typed shorthand must not be silently discarded.

Maintainer decision: either treat an explicit source requirement as ordinary source resolution, or reject it consistently while the input resolves to a watch. Keep watch-ID-based installation and its reviewed-commit rules explicit.

Completion checks:

• Flag and shorthand forms for branch/revision/version requirements have equivalent results or errors.
• The two-branch fixture never reports success while ignoring other.
• Existing watch-ID installs continue to use their accepted baseline/reviewed commit.
• Cover both a local Git path and hosted-source parsing; run swift test.

Actual Behavior

The shorthand add exits successfully and installs watched-main, even though the requested branch contains requested-other. The flag form exits 1. The executed fixture uses one source identity, so no identity collision is involved.

Related: #10 concerns scope, and #9 concerns inspection writes. This report concerns add routing and requirement validation within one project. No duplicate found.

Environment

• Source revision: 5d4987b (5d4987b9e1f94e8b9f85124299f05d5aa4f45f07).
• CLI version: 0.2.1; built successfully with swift build.
• Swift: Apple Swift 6.4 (swiftlang-6.4.0.34.1, clang-2100.3.34.1).
• OS: macOS 27.0.1 (26A434).
• Architecture: arm64.
• Git: 2.42.0. Validation date: 2026-10-17.