=== BEGIN ARTIFACT FEATURE-Accessors.md ===
# FEATURE: Accessors

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines object-field access, array indexing, optional access, and negative-index behavior. |
| Depends On  | FEATURE-Value-Model.md |
| Provides    | object fields, array indices, optional access, negative indices |
| Consumes    | jq value model |

## Questions

- None.

## Access Semantics

Object fields return the matching value or null when absent. Array indices are zero-based and support negative indices. Invalid access raises a jq runtime error unless the expression is optional, in which case the error is suppressed according to jq semantics.

## Programmatic Acceptance

=== AC value-002-conformance ===
Intent: Field access, negative indexing, and optional access produce the supplied jq behavior.
Requires: executable=python3; scope=test

import json
import subprocess

payload = '{"field":[10,20,30]}\n'
result = subprocess.run(
    ["./jq", "-c", ".field[-1], .missing?, .field[0]"],
    input=payload,
    capture_output=True,
    text=True,
)
assert result.returncode == 0
actual = [json.loads(line) for line in result.stdout.splitlines()]
expected = [30, None, 10]
assert actual == expected
=== END AC value-002-conformance ===

=== AC value-002-access-contract ===
Intent: Field access, negative indexing, and optional access produce the supplied jq behavior.
Requires: executable=python3; scope=test

import json
import subprocess

payload = '{"field":[10,20,30]}\n'
result = subprocess.run(
    ["./jq", "-c", ".field[-1], .missing?, .field[0]"],
    input=payload,
    capture_output=True,
    text=True,
)
assert result.returncode == 0
actual = [json.loads(line) for line in result.stdout.splitlines()]
expected = [30, None, 10]
assert actual == expected
=== END AC value-002-access-contract ===

## User Acceptance

- None.

## Guardrails

- Missing fields yield null rather than Python exceptions.
- Negative array indices follow jq indexing rules.
- Optional access suppresses only the applicable runtime access error.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Arithmetic-Operators.md ===
# FEATURE: Arithmetic Operators

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Define jq arithmetic, structural combination, repetition, splitting, and negation operators. |
| Depends On  | FEATURE-Type-and-Numeric-Builtins.md |
| Provides    | plus, minus, multiply, divide, modulo, negation, recursive object merge, string repetition and splitting |
| Consumes    | type and numeric builtins, jq generator evaluation |

## Questions

- None.

## Intent

Arithmetic operators apply jq's type-directed operations while preserving generator Cartesian products, immutable values, and runtime error behavior.

## Behavior

- Numeric operators perform arithmetic with jq-compatible numeric handling.
- `+` combines numbers, arrays, strings, objects, and null as specified.
- `-` subtracts numbers or removes matching array elements.
- `*` supports numeric multiplication, string repetition, and recursive object merge.
- `/` supports numeric division and string splitting.
- `%` performs numeric remainder.
- Unary negation applies only to numbers.
- Division, remainder, invalid combinations, and excessive string repetition raise runtime errors with exit status 5 when uncaught.

## Programmatic Acceptance

=== AC flow-001-conformance ===
Intent: Numeric and structural arithmetic operators produce jq-compatible results.
Requires: executable=python3; scope=test

import json
import subprocess

result = subprocess.run(
    ["./jq", "-c", "1+2, 7-3, 4*5, 7/2, 7%4, -6, [1,2]+[3], \"ab\"*2, \"a,b\"/\",\""],
    input="null\n",
    capture_output=True,
    text=True,
)
assert result.returncode == 0
actual = [json.loads(line) for line in result.stdout.splitlines()]
expected = [3, 4, 20, 3.5, 3, -6, [1, 2, 3], "abab", ["a", "b"]]
assert actual == expected
=== END AC flow-001-conformance ===

## User Acceptance

- None.

## Guardrails

- Operators must preserve output order and multiplicity.
- Values remain immutable; assignment semantics are outside this capability.
- Do not implement structural operations through implicit Python type coercion.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Assignment-Operators.md ===
# FEATURE: Deletion and Assignment Operators

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Implements jq deletion, plain assignment, update assignment, and arithmetic assignment. |
| Depends On  | FEATURE-Path-Primitives.md |
| Provides    | del, =, |=, arithmetic assignments, defined-or assignment |
| Consumes    | getpath, setpath, delpaths |

## Questions

- None.

## Scope

Implement immutable deletion and assignment over exact and iterated path expressions. Plain assignment evaluates its right-hand side against the original input and uses every produced value; update assignment evaluates against each selected path and uses the first update result. Arithmetic and defined-or assignments build on update assignment, and empty updates delete selected paths.

## Programmatic Acceptance

=== AC path-003-conformance ===
Intent: Deletion, plain assignment, update assignment, and arithmetic assignment preserve immutable jq semantics.
Requires: executable=python3; scope=test

import json
import subprocess

result = subprocess.run(
    ["./jq", "-c", "del(.obsolete), (.count = 2), (.count |= . + 3), (.count += 4)"],
    input='{"count":1,"obsolete":true}\n',
    capture_output=True,
    text=True,
)
assert result.returncode == 0
actual = [json.loads(line) for line in result.stdout.splitlines()]
expected = [
    {"count": 1},
    {"count": 2, "obsolete": True},
    {"count": 4, "obsolete": True},
    {"count": 5, "obsolete": True},
]
assert actual == expected
=== END AC path-003-conformance ===

## User Acceptance

- None.

## Guardrails

- Assignments must preserve jq's immutable snapshot semantics.
- Multi-path and generator-valued assignments must preserve output multiplicity and order.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Boolean-and-Alternative-Operators.md ===
# FEATURE: Boolean and Alternative Operators

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Define jq boolean, negation, defined-or, and defined-or assignment semantics. |
| Depends On  | FEATURE-Arithmetic-Operators.md, FEATURE-Truthiness-and-Comparison.md |
| Provides    | and, or, not, defined-or, defined-or assignment |
| Consumes    | jq truthiness, comparison, and generator evaluation |

## Questions

- None.

## Intent

This capability implements jq's boolean and fallback operators with false/null truthiness, generator-aware output, and short-circuit behavior.

## Behavior

- Only `false` and `null` are falsey.
- `and` and `or` produce boolean results for each relevant generator combination.
- `not` produces the inverse truth value.
- `//` emits non-false/non-null left outputs, otherwise all right outputs.
- `//=` updates defined-or paths while preserving immutable assignment behavior.
- Boolean and alternative expressions preserve generator ordering and short-circuit errors where jq requires them.

## Programmatic Acceptance

=== AC flow-002-conformance ===
Intent: Boolean, negation, and defined-or operators follow jq truthiness and fallback semantics.
Requires: executable=python3; scope=test

import json
import subprocess

result = subprocess.run(
    ["./jq", "-c", "(true and false), (true or false), (false|not), (null // 7), (3 // 7)"],
    input="null\n",
    capture_output=True,
    text=True,
)
assert result.returncode == 0
actual = [json.loads(line) for line in result.stdout.splitlines()]
expected = [False, True, True, 7, 3]
assert actual == expected
=== END AC flow-002-conformance ===

## User Acceptance

- None.

## Guardrails

- Do not use Python truthiness in place of jq truthiness.
- `//` must not be reduced to ordinary boolean `or`.
- Preserve generator multiplicity and fallback evaluation semantics.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Collection-Transforms.md ===
# FEATURE: Collection Transforms

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Provides jq collection transformation builtins with generator-aware recursive behavior. |
| Depends On  | FEATURE-Complex-Assignments.md, FEATURE-Generator-Core.md |
| Provides    | map, map_values, select, add, flatten, transpose, combinations, walk |
| Consumes    | assignment operators, ordered generator evaluation |

## Questions

- None.

## Scope

This feature implements collection transformation filters over arrays and objects. It preserves jq stream multiplicity, empty-result deletion behavior, recursive traversal order, bounded flattening, jagged-matrix padding, and Cartesian combinations.

## Behavior

- `map` collects all outputs produced for each input element.
- `map_values` updates each element or object value using the first produced result and removes values producing `empty`.
- `select` preserves the input only for truthy predicates.
- `add` reduces array or generated values using jq addition.
- `flatten` supports unlimited and bounded depth, rejecting negative depth.
- `transpose` pads jagged rows with `null`.
- `combinations` produces ordered Cartesian combinations.
- `walk` transforms children before their containing array or object.

## Programmatic Acceptance

=== AC data-001-conformance ===
Intent: Collection transformation builtins preserve collection shape, ordering, and Cartesian behavior.
Requires: executable=python3; scope=test

import json
import subprocess

result = subprocess.run(
    ["./jq", "-c", "map(. * 2), map_values(. + 1), select(length == 2), add, flatten(1), transpose, combinations"],
    input='[1,2]\n',
    capture_output=True,
    text=True,
)
assert result.returncode == 0
actual = [json.loads(line) for line in result.stdout.splitlines()]
assert actual[0] == [2, 4]
assert actual[1] == [2, 3]
=== END AC data-001-conformance ===

## User Acceptance

- None.

## Guardrails

- Use only Python standard-library facilities.
- Preserve generator ordering and multiplicity.
- Do not modify files under `sources/`.
=== END ARTIFACT ===