Fix: Add explicit error signalling to read() instead of silent default fallback (#390)

[GaneshPatil7517]

hello @pradeeban Sir

Problem

read() silently returned default values on all failure paths (file not found,
parse error, empty file, timeout, retry exhaustion, ZMQ failure), with no mechanism
for downstream nodes to detect whether they received real data or stale fallback values.
This is a safety concern in neuromodulation control loops.

Solution

read() now returns (data, success_flag) on every code path:

• True → real data was successfully received
• False → fallback/default value was used

Additionally, concore.last_read_status (and concore_base.last_read_status) is
set after each read to one of:
SUCCESS, FILE_NOT_FOUND, TIMEOUT, PARSE_ERROR, EMPTY_DATA, RETRIES_EXCEEDED

Example usage

val, ok = concore.read(1, "ym", init)
if not ok:
    print(f"Warning: stale data (status={concore.last_read_status})")

Backward Compatibility

Legacy callers can adapt with:
result = concore.read(...)
if isinstance(result, tuple):
    value, ok = result
else:
    value, ok = result, True

Files Changed

• concore_base.py - Core read() implementation updated with status tracking and (data, flag) returns
• concore.py - Wrapper updated; last_read_status exposed on module
• concoredocker.py - Wrapper updated; last_read_status exposed on module
• tests/test_read_status.py -15 new tests covering success, file-not-found, parse error, retries exceeded, ZMQ timeout, ZMQ error, and backward compatibility
• test_concore.py -Updated existing roundtrip test for tuple return
• test_concoredocker.py - Updated existing read tests for tuple return

Impact
Improves reliability and safety of control loops by allowing controllers to detect invalid reads.