Add coexistence-safe backend profiles

.gitattributes

@@ -3,3 +3,4 @@
 .squad/agents/*/history.md merge=union
 .squad/log/** merge=union
 .squad/orchestration-log/** merge=union
+*.sh text eol=lf

.github/workflows/ci.yml

@@ -34,8 +34,8 @@ jobs:
   # ─────────────────────────────────────────────
   # Backend-specific distribution builds (one Cargo feature each)
   #
-  # The published packages are single-backend builds: exactly one backend
-  # feature, stamped with OSCAN_DISTRIBUTION_BACKEND. Those cfg
+  # Published slim packages are single-backend builds: exactly one backend
+  # feature, stamped with the legacy OSCAN_DISTRIBUTION_BACKEND input. Those cfg
   # configurations compile different code from the default all-backends
   # build, so they are tested here as first-class configurations rather
   # than only being discovered at release time.
@@ -83,6 +83,52 @@ jobs:
           grep -qx "default-backend: ${{ matrix.backend }}" <<<"$metadata"
           grep -qx "distribution: ${{ matrix.backend }}" <<<"$metadata"
 
+  # The full package is a strict distribution too, not an unstamped development
+  # build: all backends are present, LLVM is deterministic, and packaged lookup
+  # remains enabled.
+  full-distribution:
+    name: Linux full-profile distribution build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v5
+        with:
+          submodules: recursive
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo dependencies
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.cargo/registry/index/
+            ~/.cargo/registry/cache/
+            ~/.cargo/git/db/
+          key: linux-full-profile-cargo-${{ hashFiles('**/Cargo.lock') }}
+          restore-keys: linux-full-profile-cargo-
+
+      - name: Test the full profile contract and CLI
+        env:
+          OSCAN_DISTRIBUTION_PROFILE: full
+          OSCAN_DEFAULT_BACKEND: llvm
+        run: |
+          cargo test backend::select::tests
+          cargo test --test cli_help
+
+      - name: The built compiler reports the full profile
+        env:
+          OSCAN_DISTRIBUTION_PROFILE: full
+          OSCAN_DEFAULT_BACKEND: llvm
+        shell: bash
+        run: |
+          set -euo pipefail
+          cargo build --release
+          metadata="$(./target/release/oscan --version)"
+          echo "$metadata"
+          grep -qx "backends: llvm, cranelift, c" <<<"$metadata"
+          grep -qx "default-backend: llvm" <<<"$metadata"
+          grep -qx "distribution: full" <<<"$metadata"
+
   # ─────────────────────────────────────────────
   # Verify generated docs are up to date
   # ─────────────────────────────────────────────
@@ -144,6 +190,9 @@ jobs:
       - name: Run unit tests (53 tests)
         run: cargo test
 
+      - name: Archive installer coexistence tests
+        run: python -m unittest scripts.test_installers.WindowsInstallerCoexistenceTests
+
       - name: Integration tests — positive (freestanding)
         shell: bash
         run: |

README.md

@@ -30,15 +30,18 @@ It is designed to be approachable for people and reliable for AI coding tools.
 
 Download the latest release from
 [GitHub Releases](https://github.com/lucabol/Oscan/releases). Choose the
-**LLVM package** unless you specifically need the Cranelift or C backend.
+**LLVM slim package** for the smallest recommended install, or choose **full**
+to use LLVM, Cranelift, and C from one compiler with `--backend`.
 
 | Platform | Recommended download | Notes |
 |---|---|---|
-| Windows x86_64 | `oscan-vX.Y.Z-windows-x86_64-llvm.msi` or `oscan-vX.Y.Z-windows-x86_64-llvm.zip` | The MSI is the simplest option |
-| Linux x86_64 | `oscan-vX.Y.Z-linux-x86_64-llvm.tar.xz` | Requires glibc 2.34 or newer |
+| Windows x86_64 | `oscan-vX.Y.Z-windows-x86_64-llvm.msi` or `oscan-vX.Y.Z-windows-x86_64-llvm.zip` | LLVM remains the transition default; `-full.zip` includes all backends |
+| Linux x86_64 | `oscan-vX.Y.Z-linux-x86_64-llvm.tar.xz` | `-full.tar.xz` includes all backends; LLVM requires glibc 2.34+ |
 | macOS x86_64 | `oscan-vX.Y.Z-macos-x86_64-c.tar.gz` | Requires Xcode Command Line Tools |
 
-Windows and Linux also provide `cranelift` and `c` packages. Each release
+Windows and Linux provide `full`, `llvm`, `cranelift`, and `c` profiles. Full
+contains one backend-neutral compiler; the others are smaller slim packages.
+Each release
 includes `SHA256SUMS`; keep the downloaded file's original name and verify it
 before installing. The [installation guide](docs/guide.md#installation) has
 step-by-step verification, upgrade, and uninstall instructions.
@@ -51,33 +54,38 @@ Install the latest recommended package:
 iwr -useb https://raw.githubusercontent.com/lucabol/Oscan/master/scripts/install-latest.ps1 | iex
 ```
 
-To select a backend explicitly:
+Install full, or select a slim package explicitly:
 
 ```powershell
 iwr -useb https://raw.githubusercontent.com/lucabol/Oscan/master/scripts/install-latest.ps1 -OutFile install-latest.ps1
+.\install-latest.ps1 -Profile full -SetDefault
 .\install-latest.ps1 -Backend llvm
 .\install-latest.ps1 -Backend cranelift
 .\install-latest.ps1 -Backend c
 ```
 
-Open a new terminal after installation, then check:
+Archive profiles coexist as `oscan-full`, `oscan-llvm`, `oscan-cranelift`, and
+`oscan-c`. The first archive install safely creates `oscan`; later installs
+preserve that selection unless `-SetDefault` is passed. Open a new terminal,
+then check:
 
 ```powershell
 oscan --version
 ```
 
 ### Linux
 
-Download the recommended archive and `SHA256SUMS`, verify the archive, extract
-it, and run the included installer:
+Download an archive and `SHA256SUMS`, verify it, extract it, and run the
+included installer. This example installs full and selects it as the default:
 
 ```bash
-tar xf oscan-vX.Y.Z-linux-x86_64-llvm.tar.xz
-./oscan-vX.Y.Z-linux-x86_64-llvm/install.sh
+tar xf oscan-vX.Y.Z-linux-x86_64-full.tar.xz
+./oscan-vX.Y.Z-linux-x86_64-full/install.sh --set-default
 oscan --version
+oscan app.osc --backend cranelift
 ```
 
-On Debian or Ubuntu, the LLVM package also needs:
+On Debian or Ubuntu, the LLVM and full packages also need:
 
 ```bash
 sudo apt-get install libedit2 libffi8 libxml2 libz3-4 libzstd1 zlib1g
@@ -93,8 +101,9 @@ xcode-select --install
 tar xf oscan-vX.Y.Z-macos-x86_64-c.tar.gz
 ```
 
-Copy `oscan` to a directory in your `PATH`, such as `/usr/local/bin`, then run
-`oscan --version`.
+Run the included `install.sh` to create `oscan-c` without disturbing another
+profile, then run `oscan-c --version`. Pass `--set-default` only when the plain
+`oscan` command should select this profile.
 
 ### Build from source
 
@@ -188,9 +197,9 @@ small `wc`-style command-line program step by step.
 | `oscan app.osc --debuginfo line-tables` | Keep Oscan source locations for debugging |
 | `oscan --help` | Show every option |
 
-A release package contains one backend. If you request another one, Oscan tells
-you which package to install. `--opt-level size|speed` applies to LLVM and
-Cranelift generated code; the default is `size`.
+Full contains every backend; slim packages contain one and identify the full or
+matching slim package when another is requested. `--opt-level size|speed`
+applies to LLVM and Cranelift generated code; the default is `size`.
 
 Debug information is opt-in: `--debuginfo none` is the default, while
 `--debuginfo line-tables` enables source breakpoints, stepping, stack
@@ -240,8 +249,8 @@ See the [full built-in function reference](docs/builtins.md) for signatures and
   `free` calls or a garbage collector.
 - **Targets:** release and cross-compilation support varies by platform and
   backend.
-- **Distribution:** each release package contains one backend and its required
-  support files.
+- **Distribution:** full contains all backends; coexistence-safe slim profiles
+  contain one backend and its required support files.
 
 See [Compiler Technical Details](docs/technical-details.md) for backend
 selection, package layouts, runtime and linker behavior, supported targets,

build.rs

@@ -11,29 +11,27 @@ use sha2::{Digest, Sha256};
 
 fn main() {
     stamp_git_version();
-    stamp_distribution_backend();
+    stamp_distribution_config();
     generate_native_link_assets();
     configure_inprocess_toolchain();
     generate_inprocess_link_assets();
 }
 
 // ---------------------------------------------------------------------------
-// Backend-specific distribution builds.
+// Packaged distribution builds.
 //
-// `OSCAN_DISTRIBUTION_BACKEND=llvm|cranelift|c` marks a build as *the*
-// packaged compiler for one backend: the resulting `oscan` defaults to that
-// backend deterministically instead of probing host capabilities, and every
-// other backend is compiled out (`--no-default-features --features
-// backend-<name>`). Leaving it unset is the ordinary development build: all
-// enabled features, existing capability-based default behavior.
+// `OSCAN_DISTRIBUTION_PROFILE=full|llvm|cranelift|c` identifies the package,
+// while `OSCAN_DEFAULT_BACKEND=llvm|cranelift|c` independently fixes its
+// implicit backend. `OSCAN_DISTRIBUTION_BACKEND` remains a compatibility input
+// for legacy slim builds and expands to matching profile/default values.
 //
 // The rules themselves live in `src/backend/distribution_contract.rs`,
 // shared verbatim with the compiler (which reads the stamp and unit-tests
 // the rules) so the two can never drift apart. Validation happens here, at
 // build time, so a mismatched pair — a stamp naming a disabled backend, or
 // a stamp on a build that still contains every backend — fails the build
-// with a named reason instead of producing an artifact whose name promises
-// something it is not.
+// with a named reason instead of producing an artifact whose profile/default
+// metadata promises something it is not.
 // ---------------------------------------------------------------------------
 
 mod distribution_contract {
@@ -48,7 +46,9 @@ const BACKEND_FEATURES: [(&str, &str); 3] = [
     ("c", "CARGO_FEATURE_BACKEND_C"),
 ];
 
-fn stamp_distribution_backend() {
+fn stamp_distribution_config() {
+    println!("cargo:rerun-if-env-changed=OSCAN_DISTRIBUTION_PROFILE");
+    println!("cargo:rerun-if-env-changed=OSCAN_DEFAULT_BACKEND");
     println!("cargo:rerun-if-env-changed=OSCAN_DISTRIBUTION_BACKEND");
     println!("cargo:rerun-if-changed=src/backend/distribution_contract.rs");
 
@@ -57,17 +57,29 @@ fn stamp_distribution_backend() {
         .filter(|(_, feature)| std::env::var_os(feature).is_some())
         .map(|(name, _)| *name)
         .collect();
-    let raw = std::env::var("OSCAN_DISTRIBUTION_BACKEND").unwrap_or_default();
-    let stamp = distribution_contract::validate_distribution_stamp(&raw, &enabled)
-        .unwrap_or_else(|reason| panic!("{reason}"));
-
-    // Always stamped (empty means "not a distribution build") so the
-    // compiler can read it with a plain `env!` rather than an `option_env!`
-    // whose absence would be indistinguishable from a stale build.
-    println!(
-        "cargo:rustc-env=OSCAN_DISTRIBUTION_BACKEND={}",
-        stamp.unwrap_or_default()
-    );
+    let profile_raw = std::env::var("OSCAN_DISTRIBUTION_PROFILE").unwrap_or_default();
+    let default_raw = std::env::var("OSCAN_DEFAULT_BACKEND").unwrap_or_default();
+    let legacy_raw = std::env::var("OSCAN_DISTRIBUTION_BACKEND").unwrap_or_default();
+    let config = distribution_contract::validate_distribution_config(
+        &profile_raw,
+        &default_raw,
+        &legacy_raw,
+        &enabled,
+    )
+    .unwrap_or_else(|reason| panic!("{reason}"));
+
+    let profile = config.profile.as_deref().unwrap_or("");
+    let default_backend = config.default_backend.as_deref().unwrap_or("");
+    let legacy_backend = match profile {
+        "llvm" | "cranelift" | "c" => profile,
+        _ => "",
+    };
+
+    // Always stamp every normalized value. Empty means "not configured", and
+    // lets the compiler use env! without stale option_env! ambiguity.
+    println!("cargo:rustc-env=OSCAN_DISTRIBUTION_PROFILE={profile}");
+    println!("cargo:rustc-env=OSCAN_DEFAULT_BACKEND={default_backend}");
+    println!("cargo:rustc-env=OSCAN_DISTRIBUTION_BACKEND={legacy_backend}");
 }
 
 fn stamp_git_version() {