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Physical iOS deploys never empty the app container (MOB-408) - #142
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The deploy copied BEAMs with devicectl --remove-existing-content, meant to replace Documents/otp/<app>; on an iPhone it empties the app's whole data container except the destination (SQLite, sessions, Library, tmp), on every deploy. Every copy is now a merge. For a runtime that reads them (the project's mob has ios/mob_code_versions.h and the phone has Documents/otp/<app>.versions/, which that runtime creates at boot), upload to a fresh <app>.versions/<N> numbered above every listed entry, read back <app>.beam, then copy <N>/.mob_complete: the app loads only committed versions, so an interrupted deploy leaves the previous code running. Older runtimes get a merge into Documents/otp/<app>; an error after the copy began says what each case leaves on the phone. Decision: decisions/2026-10-15-ios-deploy-never-empties-the-container.md.
Review: ios_code_plan/2 can still guess wrong when the project's mob moves across 0.9.20 without --native (a versioned upload an old runtime ignores, or a legacy merge a new runtime shadows with its committed version), and the deploy then reported success while the phone ran old code. After the relaunch, wait (up to 20 s) for Documents/mob_diag_beams_dir.txt, which every runtime since mob 0.6.2 writes at boot, to name the directory just written; otherwise fail, naming where the app booted from. Clear the partial-upload note once the marker is committed. Decision record: correct the downgrade claim, the --native wording, note concurrent deploys.
A legacy deploy expects the same Documents/otp/<app> path every time, so the previous boot's mob_diag_beams_dir.txt could satisfy the check before the new boot wrote its own. Overwrite it with a placeholder before the relaunch; a placeholder or missing file at the deadline reports that the app never said what it loaded.
GenericJam
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MOB-408, deployer half. Runtime half: GenericJam/mob#207 (mob 0.9.20).
Problem
mix mob.deployto a physical iPhone copied BEAMs withxcrun devicectl device copy to ... --destination Documents/otp/<app> --remove-existing-content true. Measured on Kevin's iPhone SE (devicectl 642.16): with that flag devicectl empties the app's whole data container except the destination. Reproduced with a blank host on mob 0.9.19 + mob_dev 0.7.26: a Documents sentinel, a SQLite row, a nested dir, aLibrary/file and a sibling inDocuments/otpwere all gone after one BEAM-only deploy.Change
--remove-existing-content; every copy is a merge.ios_code_plan/2: if the project's:mobdep shipsios/mob_code_versions.hand the phone hasDocuments/otp/<app>.versions/(the new runtime creates it at boot), upload to a fresh<app>.versions/<N>(N above every listed entry), read back<app>.beam, then copy<N>/.mob_complete. Otherwise merge intoDocuments/otp/<app>for the older runtime.Documents/mob_diag_beams_dir.txt(written at boot by every runtime since mob 0.6.2) to name the directory just written; fail otherwise, naming where the app booted from. Catches an app whose native runtime and:mobdep disagree, where the plan's guess would be ignored or shadowed.mob.deploymoduledoc,decisions/2026-10-15-ios-deploy-never-empties-the-container.md, amendments to two older records, thepersistable?/1comment.Verification
mix test(3042 passed),mix credo --strict,mix format --check-formatted,mix compile --warnings-as-errorslocally.d408with this branch + mob#207 (path deps): sentinels survived ~16 deploys (legacy push on the first--native, then versioned 1→12, GC'd behind); killing the devicectl copy mid-upload (382/448 entries) and killingmixmid-deploy both left the previous version booting; the next deploy collected the partial dirs. Old runtime (mob 0.9.19 via--native): legacy merges, nothing wiped, even with a leftover<app>.versions/. Mismatches: new deps on the old runtime and old deps on the new runtime each failed the deploy with the booted-from path instead of reporting success.Review
Codex rate-limited (until 17:26) → reviewer subagent: MERGE; its should-fix (silent stale code when the guess is wrong) is fixed by the boot check in 06a826b. Re-review: see comment below.