Require all packages to solve / compile and include all valid compilers in their metadata

.gitignore

@@ -15,6 +15,8 @@ result*
 *.sqlite3
 *.sqlite3-wal
 *.sqlite3-shm
+
+TODO.md
 .spec-results
 
 # Keep it secret, keep it safe.

AGENTS.md

@@ -0,0 +1,129 @@
+# AGENTS.md
+
+The PureScript Registry implements a package registry for PureScript. See @SPEC.md for the registry specification and @CONTRIBUTING.md for detailed contributor documentation.
+
+## Development Environment
+
+This project uses Nix with direnv. You should already be in the Nix shell automatically when entering the directory. If not, run:
+
+```sh
+nix develop
+```
+
+### Build and Test
+
+The registry is implemented in PureScript. Use spago to build it and run PureScript tests. These are cheap and fast and should be used when working on the registry packages.
+
+```sh
+spago build  # Build all PureScript code
+spago test   # Run unit tests
+```
+
+Integration tests require two terminals (or the use of test-env in detached mode). The integration tests are only necessary to run if working on the server (app).
+
+```sh
+# Terminal 1: Start test environment (wiremock mocks + registry server on port 9000)
+nix run .#test-env
+
+# Terminal 2: Run E2E tests once server is ready
+spago run -p registry-app-e2e
+```
+
+Options: `nix run .#test-env -- --tui` for interactive TUI, `-- --detached` for background mode.
+
+#### Smoke Test (Linux only)
+
+The smoke test verifies that the server comes up properly and tests deployment. Only run this test if you are making changes which could break the deployment of the server.
+
+```sh
+nix build .#checks.x86_64-linux.smoke -L
+```
+
+#### Continuous Integration via Nix Checks 
+
+There is a full suite of checks implemented with Nix which verify that packages build, formatting is correct, registry types are Dhall-conformant, and more. This is the primary check run in CI.
+
+```sh
+nix flake check -L
+```
+
+## Formatting
+
+```sh
+# Format PureScript
+purs-tidy format-in-place app app-e2e foreign lib scripts 
+purs-tidy check app app-e2e foreign lib scripts
+
+# Format Nix files
+nixfmt *.nix nix/**/*.nix
+```
+
+## Project Structure
+
+- `app/` — Registry server implementation.
+- `app-e2e/` — E2E tests for the server API.
+- `lib/` — **Public library** for consumers (Spago, Pursuit, etc.). Only types and functions useful to external tools belong here. Avoid implementation-specific code.
+- `foreign/` — FFI bindings to JavaScript libraries.
+- `scripts/` — Runnable modules for registry tasks (LegacyImporter, PackageTransferrer, PackageSetUpdater, etc.). Run via `nix run .#legacy-importer`, etc.
+- `test-utils/` — Shared test utilities.
+- `db/` — SQLite schemas and migrations (use `dbmate up` to initialize).
+- `types/` — Dhall type specifications.
+- `nix/` — Nix build and deployment configuration.
+
+## Scripts & Daily Workflows
+
+The `scripts/` directory contains modules run as daily jobs by the purescript/registry repository:
+
+- `LegacyImporter` — imports package versions from legacy Bower registry
+- `PackageTransferrer` — handles package transfers
+- `PackageSetUpdater` — automatic daily package set updates
+
+Run scripts via Nix: `nix run .#<kebab-case-name>` (e.g., `nix run .#legacy-importer`). All scripts support `--help` for usage information.
+
+## Scratch Directory & Caching
+
+The `scratch/` directory (gitignored) is used by scripts for:
+- `.cache/` — Cached API responses, downloaded packages, etc.
+- `logs/` — Log files
+- `registry/`, `registry-index/` — Local clones for testing, also modified and optionally committed to by scripts
+
+Caching is critical for the legacy importer due to the expense of downloading packages. The `Registry.App.Effect.Cache` module handles caching.
+
+## PureScript Conventions
+
+### Custom Prelude
+
+Always use `Registry.App.Prelude` in `app/` and `app-e2e/` directories:
+
+```purescript
+import Registry.App.Prelude
+```
+
+### Effects via Run
+
+Use the `run` library for extensible effects. Do NOT perform HTTP calls, console logs, or other effects directly in `Aff`. Check for existing effects in `app/src/App/Effect/` or consider adding one.
+
+### Import Style
+
+Import types unqualified, values qualified. Use shortened module names:
+
+```purescript
+import Registry.App.Prelude
+
+import Data.Array as Array
+import Data.String as String
+import Node.FS.Aff as FS.Aff
+import Parsing (Parser)
+import Parsing as Parsing
+import Parsing.Combinators as Parsing.Combinators
+import Registry.Operation (AuthenticatedData)
+import Registry.SSH as SSH
+```
+
+## Deployment
+
+Continuous deployment via GitHub Actions on master. Manual deploy:
+
+```sh
+colmena apply
+```

SPEC.md

@@ -207,7 +207,7 @@ Note:
 
 - Globs you provide at the `includeFiles` and `excludeFiles` keys must contain only `*`, `**`, `/`, `.`, `..`, and characters for Linux file paths. It is not possible to negate a glob (ie. the `!` character), and globs cannot represent a path out of the package source directory.
 - When packaging your project source, the registry will first "include" your `src` directory and always-included files such as your `purs.json` file. Then it will include files which match globs indicated by the `includeFiles` key ([always-ignored files](#always-ignored-files) cannot be included). Finally, it will apply the excluding globs indicated by the `excludeFiles` key to the included files ([always-included files](#always-included-files) cannot be excluded).
-- Dependencies you provide at the `dependencies` key must exist in the registry, and the dependency ranges must be solvable (ie. it must be possible to produce a single version of each dependency that satisfies the provided version bounds, including any transitive dependencies).
+- Dependencies you provide at the `dependencies` key must exist in the registry, the dependency ranges must be solvable (ie. it must be possible to produce a single version of each dependency that satisfies the provided version bounds, including any transitive dependencies), and transitive dependencies are not allowed (ie. any modules you import in your code must come from packages listed in your dependencies).
 
 For example:
 
@@ -234,11 +234,12 @@ For example:
 
 All packages in the registry have an associated metadata file, which is located in the `metadata` directory of the `registry` repository under the package name. For example, the metadata for the `aff` package is located at: https://github.com/purescript/registry/blob/main/metadata/aff.json. Metadata files are the source of truth on all published and unpublished versions for a particular package for what there content is and where the package is located. Metadata files are produced by the registry, not by package authors, though they take some information from package manifests.
 
-Each published version of a package records three fields:
+Each published version of a package records the following fields:
 
 - `hash`: a [`Sha256`](#Sha256) of the compressed archive fetched by the registry for the given version
 - `bytes`: the size of the tarball in bytes
 - `publishedTime`: the time the package was published as an `ISO8601` string
+- `compilers`: compiler versions this package is known to work with. This field can be in one of two states: a single version indicates that the package worked with a specific compiler on upload but has not yet been tested with all compilers, whereas a non-empty array of versions indicates the package has been tested with all compilers the registry supports.
 
 Each unpublished version of a package records three fields:
 

app/fixtures/github-packages/effect-4.0.0/bower.json

@@ -16,7 +16,6 @@
     "package.json"
   ],
   "dependencies": {
-    "purescript-prelude": "^6.0.0",
-    "purescript-type-equality": "^4.0.0"
+    "purescript-prelude": "^6.0.0"
   }
 }

app/fixtures/github-packages/transitive-1.0.0/bower.json

@@ -0,0 +1,12 @@
+{
+  "name": "purescript-transitive",
+  "homepage": "https://github.com/purescript/purescript-transitive",
+  "license": "BSD-3-Clause",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/purescript/purescript-transitive.git"
+  },
+  "dependencies": {
+    "purescript-effect": "^4.0.0"
+  }
+}

app/fixtures/github-packages/transitive-1.0.0/src/Transitive.purs

@@ -0,0 +1,6 @@
+module Transitive where
+
+import Prelude
+
+uno :: Int
+uno = one

app/fixtures/registry/metadata/prelude.json

@@ -5,8 +5,12 @@
   },
   "published": {
     "6.0.1": {
-      "bytes": 31142,
-      "hash": "sha256-o8p6SLYmVPqzXZhQFd2hGAWEwBoXl1swxLG/scpJ0V0=",
+      "bytes": 31129,
+      "compilers": [
+        "0.15.9",
+        "0.15.10"
+      ],
+      "hash": "sha256-EbbFV0J5xV0WammfgCv6HRFSK7Zd803kkofE8aEoam0=",
       "publishedTime": "2022-08-18T20:04:00.000Z",
       "ref": "v6.0.1"
     }

app/fixtures/registry/metadata/type-equality.json

@@ -5,8 +5,12 @@
   },
   "published": {
     "4.0.1": {
-      "bytes": 2184,
-      "hash": "sha256-Hs9D6Y71zFi/b+qu5NSbuadUQXe5iv5iWx0226vOHUw=",
+      "bytes": 2179,
+      "compilers": [
+        "0.15.9",
+        "0.15.10"
+      ],
+      "hash": "sha256-3lDTQdbTM6/0oxav/0V8nW9fWn3lsSM3b2XxwreDxqs=",
       "publishedTime": "2022-04-27T18:00:18.000Z",
       "ref": "v4.0.1"
     }