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ADR 0014 gave the phone a nightly and ADR 0013 rule 3 gave the desktop none, so the two heads had different answers to the same question — how does somebody try what is on main? — for no reason except the order the work happened in. This is the desktop's answer: CI publishes a build from main on every push, and it installs beside the release one rather than over it. The phone gets its separation from the platform. Android refuses an update signed by a different key, so its two channels cannot replace one another whatever anybody does. Nothing refuses anything here: Velopack applies what its feed serves and verifies no signature. So all of it is construction, and there are four separations because each closes a different door. A pack id each, so the two install in different directories and neither feed's package can be applied to the other's install. A Velopack channel each — win and win-nightly — so neither build ever reads the other's release index; the name reaches the wire as releases.win-nightly.json, which is why the constant in VelopackUpdateChannel and the argument in ci.yml have to agree or the channel answers nothing forever with no error. A prerelease flag, so the release channel cannot see the nightly even by accident. And a profile directory each, which is the one that is easy to skip and would hurt most: the cache schema is migrated on every launch, before unlock, so a shared profile means a nightly quietly upgrading a database the release build then opens. Both are installed at once by design, so that is an ordinary Tuesday rather than a corner case. The prerelease flag turns out to be load-bearing across heads as well. The phone's release channel reads releases/latest, which skips prereleases — so a desktop nightly published as a stable release would become the newest release in this repository and every phone on the release channel would start failing its check against a release carrying no Android manifest. Which build this is arrives as assembly metadata, the same mechanism and the same reasoning as the Android head: the updater needs the string rather than a branch, and a value baked into the assembly is one a crash report can be asked for. Three things read it — the feed, the prerelease flag, and the profile — and one more shows it: the titlebar says DodoSSH Nightly. Everything else that distinguishes the two is somewhere nobody is looking while typing a passphrase into one of them. The version needed a floor and it is applied to the whole build rather than to the packaging. MinVer answers 0.0.0-alpha.0.N until the first v* tag and vpk refuses anything below 0.0.1, so the job lifts the patch digit and keeps the height — through MinVerVersionOverride, so the assemblies carry the same number the installer does. Packing a version the assembly disagreed with would put one string on the preferences screen and another in the feed, which is the screen somebody reads when asked which nightly they are on. Two things found by running it rather than reading it. -t:MinVer needs a restore first, because the target arrives with the package and MSB4057 on a clean checkout reads like a typo in the workflow rather than a missing restore; the release script had the same gap and now restores before it reads. And vpk rejects an empty --packVersion loudly, which is how a broken version handoff announces itself rather than shipping a package called 1.0.0. Rule 3 is untouched. The release channel still has no job, no token and no runner, and the two channels cannot see each other. What a nightly costs is written where somebody reads it before installing one: whoever can write a release here can put a build on every nightly machine, which is fine for a build being tried and is not fine for a build holding somebody's infrastructure credentials. Verified by running the job's own steps against a clone in a Linux container: DodoSSH.Desktop.Nightly-win-nightly-Setup.exe, and an index naming pack id DodoSSH.Desktop.Nightly at 0.0.1-alpha.0.144. The upload itself is the one step not exercised — it needs a real forge and a write token, and check 16.10 is what walks the half no runner can.
143 lines
9.7 KiB
Markdown
143 lines
9.7 KiB
Markdown
# ADR 0014 — Updating the Android client, and the two channels that makes necessary
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- Status: accepted
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- Date: 2026-08-04
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- Builds on: [ADR 0011](0011-android-distribution.md), [ADR 0013](0013-desktop-distribution-and-updates.md)
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- Amends: ADR 0011's consequence that there is "no automatic update"
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## Context
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[ADR 0011](0011-android-distribution.md) settled who holds the Android release key and listed the price
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of shipping outside a store: *"There is no discovery, no automatic update, and no Play channel."* It
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also left the door open in rule 2 — *"If an update check is ever added it points at the project's
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domain"* — and named the missing update path as **the sharpest edge of the decision** for a product sold
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to teams.
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[ADR 0013](0013-desktop-distribution-and-updates.md) then built exactly that for Windows, and the
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argument it turns on applies here word for word: an SSH client holding a team's infrastructure
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credentials is precisely the software where *"the fix shipped and the user never got it"* is a security
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outcome rather than an inconvenience.
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So the question is not whether the phone should update itself. It is how, given one Android fact that
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decides everything else:
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**An installed app can only be updated by a package signed with the same key.** Not "should not" —
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Android refuses, with `INSTALL_FAILED_UPDATE_INCOMPATIBLE`. A key is an app's identity for its whole
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life.
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That collides with ADR 0011 rule 1, which puts the release key on a machine that is not a runner. CI can
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build an APK; what it cannot do is sign one that any installed copy will accept, because the debug key it
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falls back to is generated fresh in every container. An APK released from CI today could be installed
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once and never updated again — and each "update" would require an uninstall, which on this product means
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losing the local cache, the outbox and the device key.
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## Decision
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**Two channels, which are two applications, because Android has no third option.**
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1. **`release` — `dev.dodotech.dodossh`, signed by the key ADR 0011 rule 1 describes.** Cut from a `v*`
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tag by a person running `scripts/release-android.ps1` on a machine that is not a runner. No workflow
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touches it, no secret exists for it, and CI has no job that could. ADR 0011 rule 1 is unchanged, and
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its "Rejected" entry — *a release key held by CI so tagging cuts a release* — still stands.
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2. **`nightly` — `dev.dodotech.dodossh.nightly`, signed by a keystore committed to this repository in the
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open.** Cut from `main` by CI on every push, published as a pre-release on the project's own forge.
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**The key is public on purpose, and that is what makes it safe to put in CI.** ADR 0011 rule 1 exists
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because a key a workflow can reach is a key held by everyone who can change a workflow file. A key
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everybody already has cannot be stolen, needs no secret to configure, and grants nothing by being
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held — so the rule has nothing to protect. It also means this channel works on a fresh runner with no
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setup, which is the practical reason it was reachable at all.
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3. **Neither channel can update the other, by construction rather than by care.** Different package ids
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and different keys, so a mistake is an install Android refuses rather than a nightly quietly replacing
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somebody's real client. Both can be installed at once, which is the useful half: testing a nightly
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costs nobody the build they rely on.
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4. **The update check reads the project's forge and never the deployment**, which is ADR 0011 rule 2
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applied unchanged. The feed address is a `const` in `AndroidUpdateChannel` and there is deliberately
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no setting for it — a configurable update URL is exactly the knob that would let an operator, or a
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stray edit to a plaintext file, point the update path at the party ADR 0001 models as the adversary.
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◆ **Which means the repository has to be public, and it was not.** A constant address with no token is
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an anonymous read; the repository was private, so every check answered `404` and every phone reported
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itself current. See ADR 0013 §4, which had written the incompatibility down as a fact about where a
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token could live and not as something to check on the deployment. The check is one `curl` and it is
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there.
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The Android channel made it invisible rather than merely broken: it caught every network and parse
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failure and answered null, which `IUpdateChannel` then documented as meaning "this build is current". So
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a pressed CHECK NOW reported the latest build for an outage that had lasted since the feature shipped.
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It throws now. The timer still swallows — a phone on a train is not news, and a half-published release
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still fixes itself in six hours without anybody being told — and the button reports what happened,
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which is the distinction `UpdateViewModel` was written to make and was never given anything to make it
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with.
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5. **The comparison is Android's `versionCode` and not the version name.** That integer is what the
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platform itself uses to accept or refuse an install, so comparing anything else would let the client
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offer an update the platform then rejects. The feed publishes it in a small JSON manifest beside the
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APK — the counterpart of `releases.win.json` — so a check costs a few hundred bytes rather than a
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download.
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6. **Nothing is installed by the application.** It fetches, then asks Android to ask. The platform draws
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its own confirmation naming the package, and from API 26 will not draw even that until the user has
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turned this application on in the unknown-sources screen. Two deliberate answers, neither to a screen
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DodoSSH controls.
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7. **Applying does not end the process, and the shell had to learn that.** On Windows, applying replaces
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the files and restarts, so the shell disposes the vault first — that is what zeroes the identity keys,
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the vault keys and the cache key. On Android the install is a *request* and the answer may be no, so
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disposing first would answer "not now" with a locked keychain and every shell closed. `IUpdateChannel`
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gained `ApplyingEndsTheProcess`; where it is false the session is left alone, and the keys go when
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Android kills the process on the install it agreed to.
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## Consequences
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**The nightly channel is a real attack surface and should be described as one.** Anyone can build an APK
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a nightly phone will accept, because the key is public. Reaching one still means being what it fetches
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from — a release on `git.dodotech.cloud` over TLS — so the practical set is *whoever can write a release
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on this repository*, which is the same set ADR 0013 names for the desktop. That is acceptable for a
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channel whose users are testing it and is not acceptable for the one holding people's credentials, which
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is the entire reason there are two.
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**A nightly is not a beta of the release channel; it is a different application.** Moving from one to the
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other is an uninstall and a fresh enrolment. There is no migration and there will not be one — the two
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caches are encrypted under keys held by two package identities the platform keeps apart.
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◆ **The desktop has since taken this arrangement, and it had to build what Android is given.**
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[ADR 0013](0013-desktop-distribution-and-updates.md) decision 9 is this ADR applied to Windows: a nightly
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CI publishes from main, installing beside the release build rather than over it. The difference worth
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carrying back here is that every separation this ADR gets from the platform — different package identity,
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signature-checked updates, a per-app data directory — is on Windows a thing somebody had to choose and can
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therefore undo. The paragraph above about the attack surface applies there word for word, with one line
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removed: on the desktop the packages are not signed at all, so the feed is the only thing standing between
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a nightly install and an arbitrary build.
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**ADR 0011's "no automatic update" consequence is now wrong for the release channel and remains true for
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reach.** Discovery, MDM deployment and the sideloading permission are all unchanged. What changed is only
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that an installed copy can now learn a newer one exists.
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**The release channel's `versionCode` stays a hand-bumped literal**, and forgetting to bump it is caught
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rather than shipped: the release script reads what is already published and refuses to build a package
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that does not beat it.
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**Two identical launcher icons.** A nightly installed beside a release shows the same name under both.
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Four ways to vary it per channel were tried and none reached the launcher label; the findings are in
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`docs/platform-flags.md`. What tells them apart today is the package name in Android's app info, the
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version, and the channel the application names on its own preferences screen.
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## Rejected
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- **A release keystore in CI so tagging cuts the real release.** The convenience is the point of CI and
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the key is the point of ADR 0011; where they collide the key wins. This ADR is what makes that refusal
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survivable rather than merely principled — the nightly channel is where the convenience went.
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- **One channel, released from CI, signed with a stable key held as a secret.** This is the arrangement
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most projects land on and it is ADR 0011's rejected entry with an extra step: the secret is reachable
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by whoever can change a workflow file, and what it signs is the client holding the credentials.
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- **Opening the release page in a browser instead of installing.** It would work, and it moves the same
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APK through the same unknown-sources gate with one more step and no less trust. What it gives up is any
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way of knowing a fix has been fetched, which is the property this ADR exists to buy.
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- **A version-name comparison, so the feed could be a directory listing.** SemVer with prerelease heights
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needs a parser, and the parser would disagree with the platform sooner or later. The number Android
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uses is the number to compare.
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