Two related v5-sweep fixes for the online/runtime tool family:
1. Auto-login helper for headless mode
In headless mode each MCP call spawns a fresh CODESYS --noUI process,
so the login state established by connect_to_device dies before the
next call. Pre-fix, only connect_to_device and download_to_device did
their own login(); the other four (start_stop_application,
read_variable, write_variable, read_running_version_online) silently
failed in headless with 'Application not logged in.' (start/stop) or
'Invalid expression' (read/write). They worked in persistent mode
only because the login carried across calls.
Added ensure_logged_in(online_app, login_wait_seconds=30) to
ensure_online_connection.py. Idempotent: short-circuits via
online_app.is_logged_in (persistent mode is a no-op, no extra login
roundtrip). When not logged in, runs the same enum-probe + call-shape
probe + STABLE_STATES settle-wait pattern as connect_to_device.py.
Added to start_stop_application.py, read_variable.py,
write_variable.py, read_running_version_online.py.
2. _MCP_PROJECT_VERSION GVL emitted as plain VAR_GLOBAL, not CONSTANT
CODESYS inlines VAR_GLOBAL CONSTANT scalars at compile time and
strips them from the online symbol table. The whole point of
_MCP_PROJECT_VERSION.sVersion is to be readable live from the
running PLC, so CONSTANT was the wrong storage class.
read_running_version_online failed against EVERY project bumped via
the old template -- 'Invalid expression' on the runtime read.
Dropped CONSTANT from VERSION_GVL_DECLARATION_TEMPLATE in
bump_project_version.py. Existing projects auto-migrate on the next
bump because maintain_version_gvl()'s existing-GVL branch overwrites
textual_declaration with the (now non-CONSTANT) template. The string
is still effectively read-only at runtime -- only the bump tool
updates it.
read_running_version_online.py also got a more precise error message
that explicitly fingerprints the 'Invalid expression' failure mode
and points at the CONSTANT root cause. Useful for any user landing
on a project that pre-dates this fix.
Verified end-to-end against local CODESYS Control Win V3 (PLATEA, port
11740) on MCPTest2 v1.3.4.0:
- connect_to_device, get_application_state, download_to_device,
start_stop_application (both directions), read_variable
(PLC_PRG.watchdog1 = 225 ticking), write_variable (200 -> 204 in 4s
proves write took), disconnect_from_device: all 7 PASS.
- read_running_version_online failure reproduced (CONSTANT inlined),
fix landed -- next bump on MCPTest2 will validate.
37/37 unit/integration tests green. TEST_OVERVIEW.md updated with the
v5 device sweep, with the headless-mode deep-dive, and with the
broken-by-design notes on read_running_version_online.
