=== BEGIN ARTIFACT FEATURE-Collection-Transformations.md ===
# FEATURE: Collection Transformations

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Provide jq collection transformation builtins with generator-preserving behavior. |
| Depends On  | FEATURE-Reductions-And-Iteration-Control.md, FEATURE-Deletion-And-Assignment.md, FEATURE-Type-And-Numeric-Primitives.md |
| Provides    | map, map_values, select, add, flatten, transpose, combinations, walk |
| Consumes    | generator evaluator, operators, path mutation |

## Questions

- None.

## Workflow

Collection filters transform arrays and objects while preserving jq stream order and multiplicity. Implement `map`, `map_values`, `select`, `add`, `flatten`, `transpose`, `combinations`, and recursive `walk` using the established evaluator and immutable update semantics. Empty generators, nested arrays, jagged matrices, and recursive values must follow the manual and `sources/builtin.jq`.

## Programmatic Acceptance

=== AC data-001-conformance ===
Intent: The authoritative corpus slice covering collection transformations executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"map|flatten|transpose|combinations|walk"
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 data-001-conformance ===

## User Acceptance

- None.

## Guardrails

- Preserve generator ordering, multiplicity, and backtracking.
- Do not mutate input values in place.
- Use only Python standard-library facilities.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Sorting-And-Grouping.md ===
# FEATURE: Sorting And Grouping

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Provide jq structural sorting, grouping, uniqueness, and extremum builtins. |
| Depends On  | FEATURE-Truthiness-And-Comparison.md, FEATURE-Collection-Transformations.md |
| Provides    | sort, sort_by, group_by, unique, unique_by, min, max, min_by, max_by |
| Consumes    | comparison and ordering semantics, collection transformations |

## Questions

- None.

## Workflow

Implement structural ordering across jq values, including null, booleans, numbers, strings, arrays, and objects. Implement keyed sorting and grouping, duplicate removal, and minimum/maximum selection. Filter arguments may produce multiple values and must be compared in jq's prescribed lexicographic order.

## Programmatic Acceptance

=== AC data-002-conformance ===
Intent: The authoritative corpus slice covering sorting, grouping, uniqueness, and extrema executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"sort|group_by|unique|min|max"
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 data-002-conformance ===

## User Acceptance

- None.

## Guardrails

- Equality and ordering must remain consistent with jq numeric equivalence.
- Object key order must not affect structural equality.
- Preserve stable output ordering where the jq semantics require it.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Object-Entries-And-Containment.md ===
# FEATURE: Object Entries And Containment

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Provide jq key, membership, containment, and object-entry conversion builtins. |
| Depends On  | FEATURE-Field-And-Index-Access.md, FEATURE-Truthiness-And-Comparison.md, FEATURE-Collection-Transformations.md |
| Provides    | keys, keys_unsorted, has, in, inside, contains, to_entries, from_entries, with_entries |
| Consumes    | value access, equality, collection transformations |

## Questions

- None.

## Workflow

Implement key enumeration for arrays and objects, membership predicates, recursive containment and inverse containment, and conversion between objects and entry arrays. Support the documented key aliases in `from_entries` and preserve object semantics through `with_entries`.

## Programmatic Acceptance

=== AC data-003-conformance ===
Intent: The authoritative corpus slice covering keys, membership, containment, and entries executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"keys|has\(|contains|inside|to_entries|from_entries"
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 data-003-conformance ===

## User Acceptance

- None.

## Guardrails

- `keys` sorts object keys by Unicode codepoint; `keys_unsorted` preserves insertion order.
- Containment is recursive and type-sensitive.
- Missing fields and invalid access follow established jq runtime semantics.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Index-And-Membership-Utilities.md ===
# FEATURE: Index And Membership Utilities

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Provide jq index search, binary search, quantifier, emptiness, and SQL-style membership utilities. |
| Depends On  | FEATURE-Truthiness-And-Comparison.md, FEATURE-Reductions-And-Iteration-Control.md, FEATURE-Object-Entries-And-Containment.md |
| Provides    | indices, index, rindex, bsearch, all, any, isempty, IN |
| Consumes    | comparison semantics, generator evaluator |

## Questions

- None.

## Workflow

Implement substring and contiguous-array index searches, binary search over sorted arrays, short-circuiting `all` and `any`, emptiness detection, and SQL-style `IN` forms. Preserve generator behavior and avoid evaluating unnecessary values after a decisive quantifier result.

## Programmatic Acceptance

=== AC data-004-conformance ===
Intent: The authoritative corpus slice covering index, membership, quantifier, and emptiness utilities executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"indices|index\(|rindex|bsearch|any|all|IN\("
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 data-004-conformance ===

## User Acceptance

- None.

## Guardrails

- `all` and `any` must preserve jq truthiness and short-circuit behavior.
- Array searches require contiguous structural matches.
- Do not coerce unrelated jq types during membership checks.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-String-Manipulation.md ===
# FEATURE: String Manipulation

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Provide jq string trimming, case, codepoint, splitting, joining, and interpolation behavior. |
| Depends On  | FEATURE-Type-And-Numeric-Primitives.md, FEATURE-Literals-And-Interpolation.md, FEATURE-Composition-And-Cartesian-Evaluation.md |
| Provides    | trim, ltrim, rtrim, ltrimstr, rtrimstr, trimstr, startswith, endswith, ascii_downcase, ascii_upcase, explode, implode, split, join, string interpolation |
| Consumes    | string values, generator evaluator |

## Questions

- None.

## Workflow

Implement Unicode-aware whitespace trimming, prefix and suffix removal, ASCII-only case conversion, codepoint conversion, string splitting and joining, and interpolation over generator-valued expressions. Follow jq's distinctions between codepoints and UTF-8 byte lengths and its handling of null, booleans, and numbers in joins.

## Programmatic Acceptance

=== AC text-001-conformance ===
Intent: The authoritative corpus slice covering string manipulation and interpolation executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

selector = r"split|join|trim|ascii_|explode|implode|startswith|endswith"
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 text-001-conformance ===

## User Acceptance

- None.

## Guardrails

- Preserve Unicode codepoints and embedded control characters.
- `ascii_downcase` and `ascii_upcase` affect only ASCII letters.
- String operations must reject invalid input with runtime errors rather than silently coercing it.

=== END ARTIFACT ===