feat!: remove the Jetify Nix cache

[mikeland73]

First of five stacked PRs making Devbox account-free. Each PR removes one login-gated feature; the last one drops the dependencies.

The stack

Each PR is based on the one above it — review and merge bottom-up, starting here.

• main
  • 1. #2940 — remove the Jetify Nix cache  ⬅  you are here
    • 2. #2941 — remove Jetify Cloud secrets
      • 3. #2942 — remove global push/pull to Jetify Cloud
        • 4. #2943 — remove devbox auth and the identity provider
          • 5. #2944 — drop dependencies left over from the account features

Why

The Jetify Nix cache required a Jetify Cloud account: cache URIs and the S3 credentials backing them were fetched from the Jetify API using the logged-in session. Without an account it did nothing; with one it changed nix build behavior silently on every add/install/shell.

What's removed

• The devbox cache command tree: upload/copy, configure, credentials, enable, info.
• internal/devbox/providers/nixcache, which fetched AWS credentials and cache URIs from the Jetify API.
• The substituter path in installNixPackagesToStore, so nix build no longer receives --extra-substituters or AWS credentials — along with the build-from-source retry that existed only to recover from a failed cache build.
• The S3 narinfo probe in internal/devpkg. Cache lookups now query only the public https://cache.nixos.org.
• internal/setup, the sudo-task framework whose only task was the nix cache host setup, plus nix.IncludeDevboxConfig/restartDaemon, which added the user to nix trusted-users and wrote ~root/.aws/config with a credential_process pointing back at devbox cache credentials.
• The nightly cache-upload workflow.

Kept

nix.CurrentConfig/Config.IsUserTrusted stay — they are generic nix.conf helpers with their own tests, not cache-specific.

Verification

go build, go vet, go test ./... (including the full testscript suite), and golangci-lint run all pass on this branch on its own.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

Removes the login-gated Jetify Nix cache feature set as the first step toward making Devbox account-free, by deleting the cache command surface area and all code paths that fetched/used Jetify-provided caches and credentials during builds.

Changes:

• Removes the devbox cache CLI command tree and associated Devbox/Nix cache upload/copy logic.
• Removes Jetify Nix cache integration during installs (no extra substituters, no AWS credential injection, no cache-specific retry path).
• Simplifies narinfo cache probing to query only the public https://cache.nixos.org and deletes the cache-upload GitHub Actions workflow.

Reviewed changes

Copilot reviewed 16 out of 16 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
internal/telemetry/telemetry.go	Removes the cache/substituter-failure telemetry event constant.
internal/setup/setup.go	Deletes the sudo-task framework previously used for nix cache host setup.
internal/setup/setup_test.go	Deletes tests for the removed setup task framework.
internal/nix/nix.go	Removes nix daemon restart helper previously used by cache setup.
internal/nix/config.go	Removes nix.conf include writer previously used to trust users for cache access.
internal/nix/cache.go	Deletes helper for nix copy --to … used by cache upload/copy.
internal/nix/build.go	Removes support for passing extra substituters via BuildArgs.
internal/goutil/sync.go	Deletes context-aware sync.Once helpers used by nixcache integration.
internal/devpkg/narinfo_cache.go	Removes probing of Jetify caches/S3 narinfo; probes only the public binary cache.
internal/devbox/providers/nixcache/setup.go	Deletes nixcache configuration/setup implementation (trusted-users + root AWS config).
internal/devbox/providers/nixcache/nixcache.go	Deletes Jetify API integration for cache list + AWS credentials.
internal/devbox/packages.go	Removes install-time cache configuration, extra substituters, and retry-from-source fallback.
internal/devbox/cache.go	Deletes project/installable upload-to-cache functionality.
internal/boxcli/root.go	Removes registration of the cache command from the CLI root.
internal/boxcli/cache.go	Deletes the devbox cache command tree implementation.
.github/workflows/cache-upload.yml	Removes the nightly/manual cache upload workflow.

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[loreto]

LGTM