=== BEGIN ARTIFACT FEATURE-Errors-and-Optional.md ===
# FEATURE: Errors and Optional Evaluation

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines empty streams, runtime errors, exception handling, optional evaluation, and partial output behavior. |
| Depends On  | FEATURE-Composition.md, FEATURE-Process-Contract.md |
| Provides    | empty, error, try, catch, and optional filter semantics |
| Consumes    | ordered jq generator evaluation, compile and runtime exit contract |

## Questions

- None.

## Behavior

The interpreter shall support filters that produce no values, raise runtime errors, catch errors with `try` and `catch`, and suppress errors with `?`. Values emitted before an uncaught runtime error remain on standard output, and the process exits with status 5.

## Programmatic Acceptance

=== AC core-003-conformance ===
Intent: The authoritative conformance cases covering empty streams, errors, try/catch, and optional evaluation pass.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"try|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
assert summary["error"] == 0
assert result.returncode == 0
=== END AC core-003-conformance ===

## User Acceptance

- None.

## Guardrails

- Runtime failures must remain distinct from compile failures.
- Diagnostics must not replace values emitted before a runtime failure.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Truthiness-and-Comparison.md ===
# FEATURE: Truthiness and Comparison

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines jq truthiness, equality, inequality, and structural ordering semantics. |
| Depends On  | FEATURE-Generator-Core.md, FEATURE-Composition.md |
| Provides    | jq truthiness, equality, inequality, and ordering |
| Consumes    | ordered jq generator evaluation, jq value model |

## Questions

- None.

## Behavior

Only `false` and `null` are falsey. Equality and inequality shall distinguish booleans from numbers, treat numerically equivalent values as equal, compare arrays and objects structurally, and implement jq's ordering across all supported value types.

## Programmatic Acceptance

=== AC core-004-conformance ===
Intent: The authoritative conformance cases covering truthiness, equality, inequality, and ordering pass.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"==|!=|<=|>=|<|>"
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
assert summary["error"] == 0
assert result.returncode == 0
=== END AC core-004-conformance ===

## User Acceptance

- None.

## Guardrails

- Python truthiness must not be substituted for jq truthiness.
- Object key order must not affect structural equality.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Value-Model.md ===
# FEATURE: Value Model

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines the runtime representation and numeric behavior of jq values. |
| Depends On  | FEATURE-JSON-I-O.md, FEATURE-Truthiness-and-Comparison.md |
| Provides    | null, boolean, number, string, array, object, NaN, and infinity values |
| Consumes    | JSON input stream and compact JSON output |

## Questions

- None.

## Behavior

The interpreter shall represent all jq JSON value kinds, including non-finite numeric values produced by jq filters. Numeric equality, conversion, preservation, and compact serialization shall follow the supplied jq 1.8.2 behavior.

## Programmatic Acceptance

=== AC value-001-conformance ===
Intent: The authoritative conformance cases covering NaN, infinity, JSON conversion, and numeric values pass.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"nan|infinite|tojson|fromjson"
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
assert summary["error"] == 0
assert result.returncode == 0
=== END AC value-001-conformance ===

## User Acceptance

- None.

## Guardrails

- The implementation shall use only Python standard-library facilities.
- Non-finite values must not cause the process to emit invalid unhandled diagnostics on standard output.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Accessors.md ===
# FEATURE: Accessors

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines object-field access, array indexing, dynamic keys, optional access, and negative indices. |
| Depends On  | FEATURE-Value-Model.md, FEATURE-Generator-Core.md |
| Provides    | field, index, optional, dynamic-key, and negative-index access |
| Consumes    | jq value model and ordered jq generator evaluation |

## Questions

- None.

## Behavior

Object fields shall return their value or `null` when absent. Array indexing shall support integer and negative indices, dynamic keys, optional access, and jq-compatible errors for invalid or out-of-range access.

## Programmatic Acceptance

=== AC value-002-conformance ===
Intent: The authoritative conformance cases covering field access, indexing, optional access, and negative indices pass.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"\.[A-Za-z]|\[[-0-9]"
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
assert summary["error"] == 0
assert result.returncode == 0
=== END AC value-002-conformance ===

## User Acceptance

- None.

## Guardrails

- Missing object fields must yield jq's missing-field result rather than a Python exception.
- Negative array indices must follow jq semantics and must not wrap invalid assignments silently.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Slices-and-Iteration.md ===
# FEATURE: Slices and Iteration

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines array and string slicing together with array and object iteration. |
| Depends On  | FEATURE-Accessors.md |
| Provides    | array slices, string slices, array iteration, object iteration, and optional iteration |
| Consumes    | field, index, optional, and negative-index access |

## Questions

- None.

## Behavior

The interpreter shall support inclusive-exclusive slices over arrays and strings, omitted and negative bounds, fractional bounds, iteration over arrays and object values, optional iteration, and jq-compatible behavior for out-of-range operands.

## Programmatic Acceptance

=== AC value-003-conformance ===
Intent: The authoritative conformance cases covering slices and array/object iteration pass.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"\[.*:|\.\[\]"
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
assert summary["error"] == 0
assert result.returncode == 0
=== END AC value-003-conformance ===

## User Acceptance

- None.

## Guardrails

- Iteration must preserve source ordering and generator multiplicity.
- Optional iteration must suppress the applicable access error without suppressing valid outputs.
=== END ARTIFACT ===