feat: new canister setting snapshot_visibility

CHANGELOG.md

@@ -13,8 +13,10 @@ air-gapped signing
   * `icp canister status` and `icp canister settings show` now list principals one per line under their label rather than comma-separated on the label's line: `log viewer:` / `status viewer: <principal>` for the allowed viewers of a visibility setting, `controller: <principal>` for a canister's controllers. This applies to `log_visibility` and to the controller list as well, so scripts matching those lines need updating. Both lists are sorted, which the controller list previously was not.
   * `icp canister settings update` no longer lets a relative viewer edit silently revoke public access. `--add-log-viewer` / `--remove-log-viewer` and their `--*-status-viewer` counterparts are now rejected while that setting is `public`, which carries no allowed-viewers list for them to be relative to — previously they started one from empty, so adding a viewer to a public canister took access away from everyone else. The error points at `--set-*-viewer`, which states the new list outright, and at `--*-visibility controllers`, which revokes public access on its own. Both remain allowed and now warn about what they cost: replacing a `public` policy with a list, and removing the last viewer. This is breaking for the pre-existing log flags.
   * This raises the minimum replica version: reading a canister's status now requires one that reports `status_visibility`, and against an older replica `canister_status` fails to decode — which affects `icp deploy`, `icp canister status`, and `icp canister settings show`/`sync`, not just the new setting. Every mainnet subnet reports it. A `managed` network resolves the launcher to `latest` unless it pins `version:`, so only a pinned launcher older than `15.0.0-2026-08-13-03-55` is affected; raise the pin to that version or later.
+* feat: a new `snapshot_visibility` canister setting controls who may read the canister's snapshots — the `list_canister_snapshots`, `read_canister_snapshot_metadata`, and `read_canister_snapshot_data` endpoints behind `icp canister snapshot list` and `icp canister snapshot download`. It takes the same forms as `log_visibility` and `status_visibility` — `controllers` (the default), `public`, or `{ allowed_viewers: [...] }` — in a manifest's `settings:` block or with `icp canister settings update --snapshot-visibility / --add-snapshot-viewer / --remove-snapshot-viewer / --set-snapshot-viewer`, and follows the same rule that a relative viewer edit is refused while the setting is `public`. `icp canister status` and `icp canister settings show` now report it, it is applied at creation, and `icp canister settings sync` keeps it in sync. Taking, restoring, and deleting snapshots remains controller-only; the setting governs reading alone. See the [canister settings reference](docs/reference/canister-settings.md#snapshot_visibility).
 * feat: `script` build steps now receive `ICP_CLI_ENVIRONMENT`, the name of the environment the canisters are being built for, so a build can vary by environment the way a sync step already could.
 * feat: `icp completions <SHELL>` prints a shell completion script for `bash`, `zsh`, `fish`, `powershell`, or `elvish` to stdout. See the [installation guide](docs/guides/installation.md#shell-completions) for where to put it.
+* fix(sync-plugin): Wasmtime is updated 47.0.3 → 47.0.4, patching two advisories in the runtime that executes `plugin` sync steps: a WASI filesystem sandbox escape when paths or symlinks carry trailing slashes ([RUSTSEC-2026-0269](https://rustsec.org/advisories/RUSTSEC-2026-0269)), and a guest-controlled host heap allocation through WASIp3 streams ([RUSTSEC-2026-0268](https://rustsec.org/advisories/RUSTSEC-2026-0268)). The escape is the one that bears on this crate: plugins run against directories preopened under the canister directory, and containing a symlink that escapes a preopen is the runtime's job rather than something the declared-path checks can cover. Lockfile-only — no manifest, API, or minimum-toolchain change.
 * fix: canister settings from the manifest are no longer silently discarded when a canister is created through the legacy management-canister fallback (a CloudEngine subnet with no registered engine operator). That path went through `ic-utils`, which encodes `create_canister`'s argument as a bare `canister_settings` record rather than the `record { settings : opt canister_settings; ... }` the interface spec defines, so the replica read no settings at all and created the canister with defaults. `icp deploy` masked this by syncing settings afterwards; `icp canister create` does not, and left the canister unconfigured.
 * fix: `icp canister logs` output formats are corrected. `--json` now emits machine-readable JSON and the default emits the human-readable lines (the two were swapped), and `--follow --json` emits newline-delimited JSON, one record per line, streamed as each record arrives. This is breaking for scripts: parsing the default output as JSON now requires `--json`, and consumers of `--follow --json` must read one JSON object per line.