feat(opencode): make @make and @test polyglot (Python, Rust, nix devshell)

Both agents previously hardcoded the Python/uv toolchain. They now
detect the language from marker files (pyproject.toml, Cargo.toml,
flake.nix) and run the appropriate test/lint/format/type-check commands
for Python, Rust, or both. When a flake.nix devshell is present, every
toolchain command is wrapped in `nix develop -c …`.

@make's permission allowlist gains `cargo *` and `nix develop -c *`,
plus matching denies for cargo add/remove/install/publish. The
Verification Tiers and Baseline Verification sections are rewritten as
per-language bullets, and output/TDD-evidence examples are now
language-neutral. Generalised the "no Kubernetes deployments"
constraint to cover any deploy/publish.

@test gains the same devshell + cargo allows (scoped to test, check,
clippy, fmt only — no build/run/install). Its file constraint adds
`tests/**/*.rs` for Rust integration tests, with an explicit note that
Rust unit tests stay with @make because they live inside production
source files. Failure-classification hints add Rust compiler-error
mappings, and the NOT_TESTABLE table gets a "Rust unit-only" row.

config/opencode/agents/make.md

@@ -9,10 +9,48 @@ permission:
   bash:
     # Default deny
     "*": deny
-    # Python/uv development
+
+    # ── Nix devshell entry ──
+    # All toolchain commands may be wrapped in `nix develop -c <cmd>` to run
+    # them inside the project's devshell with the correct versions.
+    "nix develop -c *": allow
+    "nix develop --command *": allow
+
+    # ── Python (uv) ──
     "uv run *": allow
     "uv run": allow
-    # Deny dangerous commands under uv run (must come after allow to override)
+
+    # ── Rust (cargo) ──
+    "cargo *": allow
+    "cargo": allow
+
+    # ── Read-only inspection ──
+    "ls *": allow
+    "ls": allow
+    "wc *": allow
+    "which *": allow
+    "diff *": allow
+    "rg *": allow
+
+    # ── Explicit top-level denials ──
+    "git *": deny
+    "pip *": deny
+    "uv add*": deny
+    "uv remove*": deny
+    "cargo add*": deny
+    "cargo remove*": deny
+    "cargo install*": deny
+    "cargo publish*": deny
+    "curl *": deny
+    "wget *": deny
+    "ssh *": deny
+    "scp *": deny
+    "rsync *": deny
+    "rm *": deny
+    "mv *": deny
+    "cp *": deny
+
+    # ── Deny dangerous commands under `uv run` ──
     "uv run bash*": deny
     "uv run sh *": deny
     "uv run sh": deny
@@ -29,24 +67,6 @@ permission:
     "uv run cp *": deny
     "uv run python -c*": deny
     "uv run python -m http*": deny
-    # Read-only inspection
-    "ls *": allow
-    "ls": allow
-    "wc *": allow
-    "which *": allow
-    "diff *": allow
-    # Search
-    "rg *": allow
-    # Explicit top-level denials
-    "git *": deny
-    "pip *": deny
-    "uv add*": deny
-    "uv remove*": deny
-    "curl *": deny
-    "wget *": deny
-    "ssh *": deny
-    "scp *": deny
-    "rsync *": deny
 ---
 
 
@@ -89,7 +109,7 @@ If a task appears to touch shared interfaces but no integration contract is prov
 
 This includes:
 - Existing files to edit
-- New files to create (must be listed, e.g., "src/new_module.py (create)")
+- New files to create (must be listed, e.g. `src/new_module.py (create)` or `crates/foo/src/lib.rs (create)`)
 
 **Not supported:** File renames and deletions. If a task requires renaming or deleting files, stop and report this to the caller — they will handle it directly.
 
@@ -98,7 +118,33 @@ If you discover another file needs changes:
 2. Report which file needs modification and why
 3. Request permission before proceeding
 
-**Excluded from this constraint:** Generated artifacts (.pyc, __pycache__, .coverage, etc.) — these should not be committed anyway.
+**Excluded from this constraint:** Generated artifacts (`.pyc`, `__pycache__`, `.coverage`, `target/`, `Cargo.lock` only when allowed by acceptance criteria, etc.) — these should not be committed anyway.
+
+## Language and Toolchain
+
+You may be invoked on Python, Rust, or polyglot Nix-flake projects. Detect the toolchain at the start of the task and use the appropriate commands:
+
+| Marker file | Toolchain | Test | Lint / Format | Type-check |
+|---|---|---|---|---|
+| `pyproject.toml`, `uv.lock` | Python (`uv`) | `uv run pytest` | `uv run ruff check .` / `uv run ruff format --check .` | `uv run ty check .` or `uv run basedpyright .` |
+| `Cargo.toml` | Rust (`cargo`) | `cargo test` | `cargo clippy --all-targets -- -D warnings`, `cargo fmt -- --check` | `cargo check` (compiler-driven) |
+| `flake.nix` | Nix flake | `nix flake check` | `nix fmt -- --check` (if configured) | (n/a) |
+
+### Devshell wrapping
+
+If the project has a `flake.nix` with a `devShells.default` (or per-system equivalent), **run all toolchain commands inside the devshell** by prefixing them with `nix develop -c`:
+
+```
+nix develop -c cargo test
+nix develop -c uv run pytest
+nix develop -c cargo clippy --all-targets -- -D warnings
+```
+
+The devshell guarantees the right toolchain versions are available. Detect once at task start, decide whether to wrap, then be consistent for the whole task. **Never drop into an interactive `nix develop` (with no command).** If a non-trivial task touches multiple commands and the devshell entry overhead matters, you may still wrap each command individually — that is the supported pattern.
+
+### Polyglot tasks
+
+A task may legitimately span multiple languages (e.g. a Rust binary plus its Python test harness). Run the appropriate verification per file area; document each in the verification block.
 
 ## Dependency Constraint
 
@@ -150,10 +196,23 @@ If a task is too large, suggest splitting it.
 Every acceptance criterion must be verified. Use the strongest tier available:
 
 ### Tier 1: Automated Tests (Preferred)
-- Run existing test suite: `uv run pytest`
-- Add new test if criteria isn't covered by existing tests
-- Type check: `uv run ty check .` or `uv run basedpyright .`
-- Lint: `uv run ruff check .`
+- Run the language-appropriate test runner (see **Language and Toolchain**):
+  - Python: `uv run pytest`
+  - Rust: `cargo test`
+  - Polyglot Nix: `nix flake check`
+- Add new tests if a criterion isn't covered by existing ones.
+- Lint:
+  - Python: `uv run ruff check .`
+  - Rust: `cargo clippy --all-targets -- -D warnings`
+- Format check:
+  - Python: `uv run ruff format --check .`
+  - Rust: `cargo fmt -- --check`
+  - Nix: `nix fmt -- --check` (if configured)
+- Type check:
+  - Python: `uv run ty check .` or `uv run basedpyright .`
+  - Rust: `cargo check` (the compiler covers it)
+
+Wrap every command in `nix develop -c …` when the project has a devshell.
 
 ### Tier 2: Deterministic Reproduction (Acceptable)
 - Scripted steps that can be re-run
@@ -167,10 +226,11 @@ Every acceptance criterion must be verified. Use the strongest tier available:
 
 ### Baseline Verification
 
-Run what's configured and applicable:
-- `uv run pytest` — if tests exist and are relevant
-- `uv run ruff check .` — if ruff is configured
-- `uv run ty check .` — if ty/type checking is configured
+Run what's configured and applicable to the project's toolchain. Prefix with `nix develop -c` when a devshell exists.
+
+- **Python:** `uv run pytest`, `uv run ruff check .`, `uv run ruff format --check .`, `uv run ty check .`
+- **Rust:** `cargo test`, `cargo clippy --all-targets -- -D warnings`, `cargo fmt -- --check`
+- **Nix flake:** `nix flake check`, `nix fmt -- --check` (if configured)
 
 If a tool isn't configured or not applicable to this change, note "skipped: [reason]" rather than failing.
 
@@ -234,17 +294,22 @@ Always end with this structure:
 [1-2 sentences: what was implemented]
 
 ### Files Changed
-- `path/to/file.py` — [brief description of change]
-- `path/to/new_file.py` (created) — [description]
+- `path/to/file.{py,rs,nix,…}` — [brief description of change]
+- `path/to/new_file.{py,rs,nix,…}` (created) — [description]
 
 ### Verification
 
-**Commands run:**
-$ uv run pytest tests/test_foo.py -v
+**Commands run:** (use whichever apply to this language; wrap with `nix develop -c` if a devshell exists)
+
+$ cargo test --package my_crate
 [key output excerpt — truncate if long, show pass/fail summary]
 
+$ cargo clippy --all-targets -- -D warnings
+[summary]
+
+(or, for Python:)
+$ uv run pytest tests/test_foo.py -v
 $ uv run ruff check src/
-All checks passed.
 
 **Criteria verification:**
 | Criterion | Method | Result |
@@ -309,18 +374,20 @@ Include this section when tests were provided:
 ```
 ### TDD Evidence
 **RED (before implementation):**
-$ uv run pytest path/to/test_file.py -v
+$ <test command>     # e.g. `uv run pytest path/to/test_file.py -v`, `cargo test --test integration`
 X failed, 0 passed
 
 **GREEN (after implementation):**
-$ uv run pytest path/to/test_file.py -v
+$ <same test command>
 0 failed, X passed
 
 **Regression check:**
-$ uv run pytest path/to/affected_area/ -v
+$ <broader test command>     # e.g. `uv run pytest path/to/affected_area/ -v`, `cargo test`
 Y passed, 0 failed
 ```
 
+Use the project's actual command (Python/Rust/Nix), wrapped in `nix develop -c` if applicable.
+
 When no tests are provided (NOT_TESTABLE tasks), standard implementation mode applies unchanged.
 
 ## Scope Constraints
@@ -329,7 +396,7 @@ When no tests are provided (NOT_TESTABLE tasks), standard implementation mode ap
 - **Stay in scope** — Implement what's asked, nothing more
 - **Preserve existing patterns** — Match the codebase style unless told otherwise
 - **Don't refactor adjacent code** — Unless it's part of the task
-- **No Kubernetes deployments** — Local testing only (`--without kubernetes`); K8s verification is handled by the main agent
+- **No deployments or releases** — Local testing only. No `cargo publish`, no `uv publish`, no Kubernetes apply. Release/deploy verification is handled by the main agent.
 - **No network requests** — Don't fetch external resources unless explicitly required by the task
 - **No file renames/deletions** — Report to caller if needed; they handle directly
 

config/opencode/agents/test.md

@@ -9,22 +9,56 @@ permission:
   bash:
     # Default deny
     "*": deny
-    # Test execution
+
+    # ── Nix devshell entry ──
+    "nix develop -c *": allow
+    "nix develop --command *": allow
+
+    # ── Python (uv) — pytest + ruff only ──
     "uv run pytest *": allow
     "uv run pytest": allow
     "uv run ruff check *": allow
     "uv run ruff check": allow
-    # Read-only inspection
+
+    # ── Rust (cargo) — test/check/clippy/fmt only ──
+    "cargo test*": allow
+    "cargo nextest *": allow
+    "cargo check*": allow
+    "cargo clippy*": allow
+    "cargo fmt*": allow
+
+    # ── Read-only inspection ──
     "ls *": allow
     "ls": allow
     "wc *": allow
     "which *": allow
     "diff *": allow
-    # Search
     "rg *": allow
-    # Git inspection only (for file gate self-check)
+
+    # ── Git inspection only (for file-gate self-check) ──
     "git diff --name-only*": allow
-    # Deny dangerous commands under uv run
+
+    # ── Explicit top-level denials ──
+    "git *": deny
+    "pip *": deny
+    "uv add*": deny
+    "uv remove*": deny
+    "cargo add*": deny
+    "cargo remove*": deny
+    "cargo install*": deny
+    "cargo publish*": deny
+    "cargo build*": deny
+    "cargo run*": deny
+    "curl *": deny
+    "wget *": deny
+    "ssh *": deny
+    "scp *": deny
+    "rsync *": deny
+    "rm *": deny
+    "mv *": deny
+    "cp *": deny
+
+    # ── Deny dangerous commands under `uv run` ──
     "uv run bash*": deny
     "uv run sh *": deny
     "uv run sh": deny
@@ -41,16 +75,6 @@ permission:
     "uv run cp *": deny
     "uv run python -c*": deny
     "uv run python -m http*": deny
-    # Explicit top-level denials
-    "git *": deny
-    "pip *": deny
-    "uv add*": deny
-    "uv remove*": deny
-    "curl *": deny
-    "wget *": deny
-    "ssh *": deny
-    "scp *": deny
-    "rsync *": deny
 ---
 
 
@@ -81,14 +105,31 @@ When no Test Design is provided, derive test cases directly from the acceptance
 ## File Constraint (Strict)
 
 **You may ONLY create or modify files matching these patterns:**
+
+Python:
 - `**/test_*.py`
 - `**/*_test.py`
 - `**/conftest.py` (NEW files in new directories only — never modify existing conftest.py)
 - `**/test_data/**`
 - `**/test_fixtures/**`
 
+Rust (integration tests only — see "Rust unit tests" below):
+- `tests/**/*.rs` (crate-level integration tests directory)
+- `**/tests/**/*.rs` (per-crate integration tests in workspace layouts)
+- `**/test_data/**`
+- `**/test_fixtures/**`
+
 **You may NOT modify production/source code under any circumstances.**
 
+### Rust unit tests
+
+Rust unit tests live inside production source files (inside `#[cfg(test)] mod tests { ... }` blocks in `src/**/*.rs`). Because that would require modifying production code, **you do not write Rust unit tests.** Options when the task spec requests unit-level coverage in Rust:
+
+1. Convert to an integration test under `tests/` if the unit is part of the public API.
+2. Return `NOT_TESTABLE` with reason `pure-wiring` or `external-system` if no integration-level seam exists, and let `@make` write the in-source tests.
+
+Report this constraint to the caller rather than silently degrading coverage.
+
 If you believe source code needs changes to be testable, report this to the caller — do not edit it yourself.
 
 This constraint is enforced by a post-step file gate. Violations cause your output to be discarded.
@@ -106,14 +147,27 @@ This constraint is enforced by a post-step file gate. Violations cause your outp
 - Tests that assert on mock behavior rather than real behavior
 - Tests requiring excessive mocking (>2 mocks suggests design problem — report it)
 
-**Follow existing codebase patterns:**
+**Follow existing codebase patterns** (per language):
+
+Python:
 - Use pytest (not unittest.TestCase)
 - Colocate tests with source code (match the project's existing pattern)
-- Use existing fixtures from conftest.py when available
+- Use existing fixtures from `conftest.py` when available
 - Use `@pytest.mark.parametrize` for multiple cases of the same behavior
-- Use `unittest.mock` only for external services (W&B, Neptune, S3) or slow I/O
+- Use `unittest.mock` only for external services or slow I/O
 - Organize related tests in plain classes (not TestCase subclasses)
 
+Rust:
+- Integration tests only (see File Constraint). Place under `tests/<feature>.rs` or `tests/<feature>/main.rs`.
+- Use the standard `#[test]` attribute. For async tests, match what the crate already uses (`#[tokio::test]`, `#[async_std::test]`, etc.).
+- For parameterised cases, prefer `rstest` if the crate already uses it; otherwise simple loops or per-case `#[test]` functions.
+- Use `assert_eq!`, `assert_ne!`, `assert!` with informative messages.
+- Use existing test helpers from the crate's `tests/common/` module when present.
+
+### Devshell wrapping
+
+If the project has a `flake.nix` with a `devShells.default`, wrap every test/lint command with `nix develop -c …` (e.g. `nix develop -c cargo test`, `nix develop -c uv run pytest`). The devshell guarantees the right toolchain is on PATH.
+
 ## Process
 
 1. **Read** existing code to understand the interface being tested
@@ -133,13 +187,20 @@ After running tests, classify each failure:
 | `TEST_BROKEN` | Test itself has errors | Collection error, fixture error, syntax error in test | No — fix before proceeding |
 | `ENV_BROKEN` | Environment issue | Missing dependency, CUDA unavailable | No — report as BLOCKED |
 
-**Mapping hints:**
+**Mapping hints (Python):**
 - `ImportError` / `ModuleNotFoundError` on the module being tested → `MISSING_BEHAVIOR`
 - `AttributeError: module 'X' has no attribute 'Y'` → `MISSING_BEHAVIOR`
 - `AssertionError` with actual vs expected values → `ASSERTION_MISMATCH`
 - `FixtureLookupError`, `SyntaxError` in test file, collection errors → `TEST_BROKEN`
 - `ModuleNotFoundError` on a third-party package → `ENV_BROKEN`
 
+**Mapping hints (Rust):**
+- `error[E0432]: unresolved import` / `error[E0425]: cannot find function/value` for the symbol under test → `MISSING_BEHAVIOR`
+- `error[E0599]: no method named ...` on a real but incomplete type → `MISSING_BEHAVIOR`
+- Test panics with `assertion failed: ... left: ..., right: ...` → `ASSERTION_MISMATCH`
+- Test file fails to compile due to its own bug (typo, wrong type, unused-import-as-error) → `TEST_BROKEN`
+- `linker not found`, missing system library, missing feature flag → `ENV_BROKEN`
+
 Only `MISSING_BEHAVIOR` and `ASSERTION_MISMATCH` qualify as valid RED. Fix `TEST_BROKEN` before reporting. Report `ENV_BROKEN` as BLOCKED.
 
 ## Escalation Flag
@@ -159,10 +220,11 @@ You may return `NOT_TESTABLE` only for these allowed reasons:
 
 | Reason | Example |
 |--------|---------|
-| **Config-only** | .gitignore change, pyproject.toml metadata, env var |
+| **Config-only** | `.gitignore` change, `pyproject.toml` / `Cargo.toml` metadata, env var, `flake.nix` input bump |
 | **External system without harness** | Change only affects API call to service with no local mock possible |
 | **Non-deterministic** | GPU numerical results, timing-dependent behavior |
-| **Pure wiring** | Decorator swap, import reorganization, no logic change |
+| **Pure wiring** | Decorator swap, import / `use` reorganization, no logic change |
+| **Rust unit-only** | Coverage requires `#[cfg(test)]` mod tests in production source; @test cannot write those — let @make handle it |
 
 Must provide:
 - Which allowed reason applies
@@ -179,17 +241,17 @@ NOT_TESTABLE requires `@check` sign-off before proceeding.
 ### Verdict: [TESTS_READY | NOT_TESTABLE | BLOCKED]
 
 ### Test Files
-- `path/to/test_file.py` — [what it tests]
+- `path/to/test_file.{py,rs}` — [what it tests]
 
 ### Handoff
-- **Pytest command:** `uv run pytest path/to/test_file.py -v`
+- **Test command:** the exact command (e.g. `uv run pytest path/to/test_file.py -v`, `cargo test --test integration_foo`, wrapped in `nix develop -c …` if applicable)
 - **Expected failing tests:** test_name_1, test_name_2, ...
 - **Failure reasons:** MISSING_BEHAVIOR (all) | mixed (see detail)
 - **Escalate to @check:** true/false
 - **Escalation reason:** [only if true — which trigger]
 
 ### RED Verification
-$ uv run pytest path/to/test_file.py -v
+$ <test command>
 [key failure output — truncated, not full dump]
 
 ### Failure Detail (only for mixed/ambiguous failures)