lsp: declarative action registry + cross-channel language server

Make `testium lsp` (and the testium_assist editor extension that spawns it)
work from every distribution channel: source, wheel, PyInstaller, Flatpak,
AppImage.

Two enablers:

1. Declarative ACTIONS registry. The TestItemActions parents (console, plot,
   json_rpc) now declare their nested actions as a class attribute
   `ACTIONS = {yaml_key: class}`, mirroring PARAMS. The base __init__ seeds
   action_classes from type(self).ACTIONS; register_actions() is kept only as
   an imperative escape hatch. lsp/schema.py reads ACTIONS directly, dropping
   the inspect.getsource/AST walk that returned no actions in a frozen
   PyInstaller build (no .py source on disk).

2. pygls bundled per channel. Kept as the pyproject [lsp] extra (lean
   `pip install testium`), layered into each full-app channel:
   - build_env.sh installs pygls into test/tmp/.venv (source run + PyInstaller
     build env)
   - AppImage installs the wheel as `…whl[lsp]`
   - Flatpak adds a python3-lsp network-pip module (matches the manifest's
     global --share=network)
   - PyInstaller .spec collect_submodules(pygls/lsprotocol) + hiddenimports for
     the lazily-imported lsp/lsp.server/lsp.schema

test/validation/lsp_smoke.py (run by run.sh before the suite) enforces both
per channel: `<channel> schema` must keep console/plot/json_rpc actions and
`<channel> lsp` must answer an initialize request without reporting pygls
missing. Verified for source mode; the other channels need a rebuild to verify.

DESIGN.md updated (declarative section + new "Language server across channels"
subsection + Recent fixes).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

DESIGN.md

@@ -254,13 +254,25 @@ Validation is **opt-in per subclass**: while a subclass keeps `PARAMS = None` (t
 
 Diagnostics are currently **warnings** for unknown params so an out-of-tree `.tum` with a pre-existing typo doesn't suddenly fail. The flip to a hard error is a one-line change in `_validate_declared_params()` once the user is comfortable.
 
-The schema is also designed to be the source of truth for a future LSP server and for auto-generated manual sections: `ParamSet.to_schema()` returns the JSON-Schema-shaped representation that those consumers will read.
+Action items follow the same declarative principle. A `TestItemActions` parent (`console`, `plot`, `json_rpc`) declares its nested actions as a class attribute `ACTIONS = {yaml_key: action_class}` (e.g. `{"open": TestItemConsoleOpen, "write": …}`), mirroring `PARAMS`. The base `TestItemActions.__init__` seeds `self.action_classes` from `type(self).ACTIONS`; the imperative `register_actions(**…)` method is retained only as an escape hatch for actions that can't be known at class-definition time (none today). Because the action classes are always defined above their parent in the module, the class-level dict resolves without forward-reference gymnastics.
+
+The schema is the realized source of truth for the LSP server (`testium lsp`), the `testium schema` CLI dump, and future auto-generated manual sections: `ParamSet.to_schema()` returns the JSON-Schema-shaped representation, and `lsp/schema.py` reads both `PARAMS` and `ACTIONS` **purely from class attributes** — no `inspect.getsource`/AST parsing. This is what lets the full schema (including nested actions) survive a frozen PyInstaller build where the `.py` source isn't on disk.
+
+### Language server (`testium lsp`) across channels
+
+The `testium_assist` editor extension is a thin LSP client that spawns `testium lsp` and talks JSON-RPC over stdio, so the language server must work from *every* distribution channel. Two requirements:
+
+1. **`pygls` (+ `lsprotocol`, `cattrs`, `attrs`, `typing_extensions`) must be bundled.** It is the pyproject `[lsp]` extra (kept optional so a plain `pip install testium` stays lean), wired into each full-app channel: `build_env.sh` installs it into the shared `test/tmp/.venv` (covers **source run** and the **PyInstaller** build env); the **AppImage** installs the wheel as `…whl[lsp]`; the **Flatpak** adds a `python3-lsp` pip module (network-at-build, consistent with the manifest's global `--share=network`); the **PyInstaller** `.spec` force-collects the submodules via `collect_submodules` + explicit `hiddenimports` (including the lazily-imported `lsp`, `lsp.server`, `lsp.schema`).
+2. **The schema must build without source** — handled by the declarative `PARAMS`/`ACTIONS` above; PyInstaller is the only channel that strips `.py` source, and it no longer matters.
+
+`test/validation/lsp_smoke.py` enforces both per channel: `run.sh` calls it before launching the suite, asserting that `<channel> schema` returns JSON whose `console`/`plot`/`json_rpc` items still carry their actions, and that `<channel> lsp` answers an `initialize` request with capabilities (and never reports the pygls dependency missing). So `./test/validation/run.sh --mode flatpak|pyinstaller|appimage` now fails loudly if a channel ships a broken or pygls-less language server.
 
 ### Version reporting (`interpreter/utils/version.py`)
 
 Both Flatpak and AppImage export `TESTIUM_VERSION` from a launcher (Flatpak: launcher script in `org.testium.Testium.yaml`; AppImage: `runtime.env` in `AppImageBuilder.yml`). `get_testium_version()` checks `/.flatpak-info` / `APPIMAGE` and reads `TESTIUM_VERSION` rather than relying on package metadata or repo introspection.
 
 ## Recent fixes / notable changes
+- LSP across packaging channels: `testium lsp` (and the `testium_assist` editor extension that spawns it) now works from source, wheel, PyInstaller, Flatpak and AppImage. Two enablers — (1) action items declare a class-level `ACTIONS = {key: class}` registry (like `PARAMS`), so `lsp/schema.py` builds the full schema from class attributes with no `inspect.getsource`/AST (which broke under frozen PyInstaller); (2) the `[lsp]` extra (pygls) is wired into every full-app channel. `test/validation/lsp_smoke.py`, run by `run.sh` before the suite, asserts per-channel that `schema` keeps its actions and `lsp` answers `initialize`. See the matching architecture sections.
 - Declarative test item parameters (v0.2): each `TestItem` subclass exposes a `PARAMS = ParamSet(...)` class attribute consumed by the base `__init__`. Catches unknown YAML keys (typo warnings listing the accepted names) and missing required params (load-time errors with `.tum` context). Lays the schema foundation for a future LSP server and auto-generated manual sections. See the matching architecture section.
 - Flatpak: `py_func` / `lua_func` / `run` sub-instance now execute on the host via `flatpak-spawn --host`. The previous attempt to inject host lib dirs into the sandbox's `LD_LIBRARY_PATH` was abandoned — host shared libs are ABI-incompatible with the Flatpak runtime's glibc and would trip `_dl_call_libc_early_init`. The manifest gained `--talk-name=org.freedesktop.Flatpak` so the spawn proxy call is allowed. The testium package is staged once per process under `/tmp` (shared with the host) so the host interpreter can locate `py_func` / `lua_func`.
 - Validation suite: single entry point with `--mode source|wheel|pyinstaller|flatpak|appimage` to validate every packaging channel against the same items. Per-mode report filenames prevent clobbering.