FEATURE: Diagnostics and Standard Error Output

Workflow

Implement debug and stderr as side-effecting filters that preserve the required value stream, and implement halt_error with its documented stderr emission and exit behavior. Keep diagnostic output separate from JSON values written to stdout.

Programmatic Acceptance

=== AC io-002-diagnostics-conformance ===
Intent: The authoritative corpus cases covering debug, stderr, and halt_error execute and pass.
Suite: scoped
Requires: executable=python3; scope=test

import json import os import subprocess import sys

selector = r"debug|stderr|halt_error" result = subprocess.run( [sys.executable, "sources/run_conformance.py", "--select", selector, "--json"], capture_output=True, text=True, env={**os.environ, "JQ": f"{os.getcwd()}/jq"}, ) print(result.stdout) print(result.stderr, file=sys.stderr) report = json.loads(result.stdout) summary = report["summary"] assert sum(summary.values()) > 0 assert summary["fail"] == 0 and summary["error"] == 0 assert result.returncode == 0 === END AC io-002-diagnostics-conformance ===

=== AC io-002-channels ===
Intent: The selected corpus exercises diagnostic filters while the conformance runner observes the declared process contract.
Suite: scoped
Requires: executable=python3; scope=test

import json import os import subprocess import sys

selector = r"debug|stderr|halt_error" result = subprocess.run( [sys.executable, "sources/run_conformance.py", "--select", selector, "--json"], capture_output=True, text=True, env={**os.environ, "JQ": f"{os.getcwd()}/jq"}, ) print(result.stdout) print(result.stderr, file=sys.stderr) report = json.loads(result.stdout) summary = report["summary"] assert sum(summary.values()) > 0 assert summary["fail"] == 0 and summary["error"] == 0 assert result.returncode == 0 === END AC io-002-channels ===

User Acceptance

• None.

Guardrails

• Diagnostics must never be emitted as JSON values on stdout.
• Do not assert diagnostic message wording; preserve only the documented channels and exit semantics.