## What Problem This Solves
Repository scripts retain private copies of shared tooling helpers and an unused translation subprocess runner, increasing maintenance work across sibling scripts.
## User Impact
Internal tooling cleanup: existing flags, diagnostics, generated bytes, JSON formats, exit codes, and cleanup policies stay the same. The build wrapper additionally detects forbidden dynamic-import warnings when compiler output splits the warning marker across chunks.
## Why This Change Was Made
- Remove the retired i18n process runner. Its final production caller moved to the shared formatter in #95534; retain real CLI/privacy/provider tests and run their subprocesses with the existing dependency.
- Share Docker resource, signal-trap, platform, workspace-staging, and plugin-selection helpers while retaining each caller's environment precedence and lifecycle decisions.
- Reuse existing E2E fixture JSON/assertion and package-path helpers; retain distinct write modes, recovery ordering, and mounted/frozen harness contracts.
- Share macOS guest desktop-user/home resolution through its existing owner while preserving per-caller timeout policy.
- Route release/mobile flags through the existing version flag specifications, preserving split-only values, duplicate/mode rules, help timing, and error text. Reuse existing retry sleep and comparator owners and remove an unreachable iOS output branch.
- Reuse existing guard entrypoint, failure-trailer, diagnostic-line, and metadata-normalization owners.
Measured reduction: **732 net production lines**, with test changes counted separately. PR tooling and its protected import closure, CI planners/shards, baselines, and generated artifacts are unchanged.
## Fixes Found Along the Way
The tsdown scanner checked each raw output chunk for its warning marker. It now checks the existing combined-line buffer. The regression exercises every split inside the marker and fails on the original source for the intended missing-warning assertion.
## Evidence
- Blacksmith Testbox `tbx_01m3tp4sabwd0807kj9jkqqmbr`: frozen dependency install and candidate source-byte verification; all nine changed test files and 59 selected sibling files passed, including real CLI, package fixture, recovery, Docker harness, and Parallels transport contracts.
- Generated channel metadata is byte-identical; differential metadata normalization cases passed.
- SDK surface check passed. Independent isolated Codex review completed with no P0–P2 findings.
- Initial changed checks caught an invalid direct source import in a proposed snapshot-distance consolidation; that independent change was withdrawn. No boundary exception was added. The final changed checks pass, including script/test lint and Docker shell/scheduler checks; madge reports 0 cycles and the runtime import check reports 0 cycles.
- Per-file single-worker wall time for changed suites: translation 9.92s; Docker helper 38.88s; live Docker auth 1.71s; mobile ref 2.36s; mobile release 6.23s; release preparation 2.42s; version 2.04s; installer 15.01s; tsdown 2.70s. The existing Docker helper suite executes shell/process cleanup and container-command boundary fixtures; new assertions reuse those fixtures. New parser/scanner cases use no sleeps or polling.
Hosted CI will be verified against this PR's exact pushed head. No live deployment or release was performed.
