backrest: register the Hola backup hooks itself — today provides: backup@1 asserts coverage the bundle can't enforce

[pofallon]

What

src/backrest/src/manifest.json:11 declares "provides": ["backup@1"], and Hola treats that as the host's backup provider — the dashboard's Backups page reports every accepting app's coverage on the strength of it.

But the bundle only writes the two broker scripts (src/compose.yaml:59,126,154 → /config/hola/backup-prepare.sh, /config/hola/backup-finalize.sh). It never registers them with Backrest. BACKREST_CONFIG points at /config/config.json (compose.yaml:6) and nothing generates or patches it, so out of the box a scheduled run calls neither hook.

Our own README says so (README.md:33): "Wire up the hooks — see below. Without them a scheduled run copies live [data]", then asks the operator to add both as Command hooks on the repo or plan in the Backrest UI, with the right conditions (CONDITION_SNAPSHOT_START / ON_ERROR_CANCEL, CONDITION_SNAPSHOT_END / ON_ERROR_IGNORE).

Why it matters

Between install and that manual step, the two facts an operator sees are both wrong in the reassuring direction:

• provides: ["backup@1"] is true at the contract layer, so Hola shows a provider is installed;
• the coverage rollup reports each app's participation — quiesced, partial — describing hooks that will not run.

So a Postgres-backed app displays as quiesced while its backup is in fact a live-file copy: crash-consistent at best. The failure is silent, it is only visible by opening the Backrest UI and noticing the hook list is empty, and it points the wrong way — the dashboard actively reassures.

This is also the only thing standing between backup@1 and being genuinely end-to-end, since the broker side (prepare → poll → finalize, failing closed) is already implemented in the scripts and exercised by the server.

Suggested fix

Have backrest-hooks-init own the registration, not just the script bodies:

• If /config/config.json does not exist, write one whose repo/plan carries both Command hooks.
• If it does exist, patch it idempotently — add the two hooks when absent, leave everything else alone, and don't re-add on every boot (the same stamped one-shot shape calibre-web uses for its settings, see fix(calibre-web): apply the reader model on upgrades, not just fresh installs #158).
• Keep the scripts where they are; only the wiring changes.

Worth deciding alongside: whether a provider that cannot self-register should be allowed to declare provides at all, or whether Hola should surface "provider installed but hooks unregistered" — that half belongs in try-hola/hola.

Verified

• manifest.json:11-12 — provides/accepts both backup@1.
• compose.yaml:59,126,154 — writes and chmod +xes both scripts; no config.json handling anywhere in the file.
• README.md:33,38-54 — documents the manual step and its consequence.

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https://claude.ai/code/session_01Vck5KSX2CLxhohx14nb5Sh