v0.284.0 — a box deletes old app images (decision 53, R-736); an after_install app is held until its known login is replaced (R-741)

Image retention: after a done/undone guarded Update and at remove, an app's images older than its running
and previous one are deleted — never an image any container, installed compose or installed/previous record
names (box-wide keep set read at delete time); exact id, never forced or pruned; paused while any update runs;
a one-time sweep of catalog app images at the first start. Install hold: an after_install app is installed
behind the setup gate's door and opens when after_install succeeds or the household says it changed the login.
Tests TestImageRetention_* and TestInstallHold_* with red-proofs; parity fixture for the held card.

MinAgent: 0.131.0 (unchanged).

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0159rPz1ZhFKsS53msqPYxtS

REUSE.md

@@ -28,6 +28,8 @@
 | `stacks.RunAfterInstall` / `expandAfterInstall` / `web.defaultLoginInEffect` (v0.279.0, decision 45) | controller/internal/stacks/after_install.go · controller/internal/web/known_login.go | `(name, wait)` / `(cmd, allowed, env)` / `(meta, cfg, installed)` | A fresh install replaces a known default login; the page says when a default is still in effect | **Only from the deploy-done hook** — never after a restore/kept load (R-694). A `success:` marker is required (exit 0 lies). Never log the expanded command |
 | `stacks.OpenSetupGate` / `SetupGateTick` / `SetupGateHost` · `web.ServeGateAuth` / `ServeGateStart` (v0.280.0, decision 46) | controller/internal/stacks/setup_gate.go · controller/internal/web/setup_gate.go | `(name, by)` / `()` / `(host)` · handlers | The setup gate: a `setup_gate: true` install is closed to everyone but the household until its probe or the household's press opens it | **Write the gate BEFORE the first start** (spike F2). Open = record first, then remove the file. Never widen the dashboard cookie — the handshake mints a host-bound one-use token |
 | `stacks.OpenSignupWindow` / `SignupBlocked` / `SetupGateProbe` · `web.ServeSignupClosed` (v0.281.0, decision 47) | controller/internal/stacks/signup_block.go · controller/internal/web/setup_gate.go | `(name)` | Sign-up closed at the app's own address once the gate opens; the household's 15-minute window; the press asks the probe | **The block goes up BEFORE the gate comes down** (a failed write keeps the gate closed). Never on an app this box did not gate |
+| `stacks.OpenInstallHold` / `installHoldTick` (v0.284.0, R-741) | controller/internal/stacks/install_hold.go | `(name, by)` / `()` | An `after_install` app held behind the setup gate's door until its known login is replaced | **Written before the first start**, like the gate; opens on `after_install` success or the household's "I changed it"; the door (`SetupGateHost`) reads holds first |
+| `stacks.RetainImagesAfterUpdate` / `RetainImagesAfterRemove` / `RunImageRetentionOnce` · seam `imageDocker` (v0.284.0, decision 53) | controller/internal/stacks/image_retention.go | `(name, previous)` / `(name, repos)` / `()` | Deletes an app's images older than its running + previous one | **The keep set is box-wide and read at delete time** (containers, installed composes, installed/previous records); exact id, never forced or pruned; skipped while any update runs; tests use the `imageDocker` seam, never Docker |
 | `stacks.CloseSignupNow` / `CloseSignupOffered` / `applyNativeLock` (v0.282.0, decisions 47/49) | controller/internal/stacks/after_setup.go | `(name)` | The app's own sign-up switch after the setup; "close sign-up now" for an app installed before the rule | **Check the installed compose reads the variable** (an old install carries the old compose until its next update) — never record a lock that is not there. One run per app at a time (`nativeLockBusy`) |
 | `backup.judgeCopy` / `HollowCopies` / `SetHollowCopyNotify` (Part D, v0.279.0) | controller/internal/backup/hollow_watch.go | `(app, tier, unitDir)` | A RUNNING app whose newest copy holds no data → operator digest once/day + page sentence | Uses `unitCarriesData` (the manifest, never size); a stopped held app is never flagged |
 | `web.nightChain` (R-705, v0.279.0) | controller/internal/web/night_chain.go | `POST /api/debug/backup/night-chain` | The night's four legs now, in order | Refuses while any op/update/chain runs; the leg uses `RunUpdateLegNow` |