=== BEGIN ARTIFACT FEATURE-Destructuring-Patterns.md ===
# FEATURE: Destructuring Patterns

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines array and object destructuring bindings and alternative matching. |
| Depends On  | FEATURE-Variable-Bindings.md, FEATURE-Conditionals-And-Exception-Flow.md, FEATURE-Declarations-And-Control-Syntax.md |
| Provides    | Array patterns, object patterns, missing bindings, ?// alternatives |
| Consumes    | Lexical bindings, generator errors, function scope |

## Questions

- None.

## Purpose

Support jq destructuring patterns in `as` bindings and the `?//` destructuring alternative operator.

Array patterns bind positional elements, using `null` for missing positions. Object patterns bind named fields, including nested patterns and renamed fields. Alternative patterns retry when matching or downstream evaluation fails, exposing unmatched variables as `null`.

## Implementation Requirements

- Parse array and object patterns with nested patterns.
- Bind variables lexically for the remainder of the query.
- Preserve generator ordering and backtracking.
- Implement `?//` alternatives, including retry after downstream errors.
- Reject malformed patterns and undefined bindings at compile time.
- Preserve `null` bindings for variables absent from the successful alternative.

## Programmatic Acceptance

=== AC destructuring-conformance ===
Intent: The authoritative corpus slice covering destructuring syntax and alternatives executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

select = r"\?//| as \{"
result = subprocess.run(
    [sys.executable, "sources/run_conformance.py", "--select", select, "--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 destructuring-conformance ===

## User Acceptance

- None.

## Guardrails

- Do not treat destructuring bindings as mutable variables.
- Do not retry an alternative after a successful alternative completes without error.
- Do not load module fixtures while parsing or evaluating destructuring syntax.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Path-Discovery.md ===
# FEATURE: Path Discovery

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines jq path discovery, path filtering, and projection operations. |
| Depends On  | FEATURE-Slices-And-Iteration.md, FEATURE-Destructuring-Patterns.md, FEATURE-Recursive-Generators.md |
| Provides    | path, paths, pick, path projections |
| Consumes    | Accessors, iteration, generator evaluation |

## Questions

- None.

## Purpose

Implement jq's path-oriented filters for discovering, filtering, and projecting nested array and object locations.

## Implementation Requirements

- Implement `path(expression)` for exact and pattern path expressions.
- Implement `paths` and `paths(filter)` with stable traversal order.
- Represent paths as arrays containing string object keys and integer array indexes.
- Exclude the root path from `paths`.
- Implement `pick(path-expressions)` while preserving missing projected fields as `null`.
- Raise runtime errors for invalid path expressions.
- Preserve path behavior through recursive descent and generators.

## Programmatic Acceptance

=== AC path-discovery-conformance ===
Intent: The authoritative corpus slice covering path discovery and projection executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

select = r"path\(|paths|pick\("
result = subprocess.run(
    [sys.executable, "sources/run_conformance.py", "--select", select, "--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 path-discovery-conformance ===

## User Acceptance

- None.

## Guardrails

- Do not emit paths in traversal order different from jq's generator order.
- Do not confuse a projected value with its path representation.
- Do not silently accept invalid path expressions.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Path-Primitives.md ===
# FEATURE: Path Primitives

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines nested path lookup, creation, replacement, and deletion primitives. |
| Depends On  | FEATURE-Path-Discovery.md, FEATURE-Field-And-Index-Access.md |
| Provides    | getpath, setpath, delpaths |
| Consumes    | Path discovery, immutable value model |

## Questions

- None.

## Purpose

Implement jq's primitive operations for reading, setting, and deleting values at nested paths.

## Implementation Requirements

- Implement `getpath(paths)` for one or more paths.
- Implement `setpath(path; value)` with nested object and array creation.
- Implement `delpaths(paths)` for multiple nested deletions.
- Preserve immutable input values and return updated copies.
- Handle missing object fields and array positions according to jq semantics.
- Reject invalid path component types and invalid array operations with runtime errors.
- Enforce path depth limits required by the corpus.

## Programmatic Acceptance

=== AC path-primitives-conformance ===
Intent: The authoritative corpus slice covering getpath, setpath, and delpaths executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

select = r"getpath|setpath|delpaths"
result = subprocess.run(
    [sys.executable, "sources/run_conformance.py", "--select", select, "--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 path-primitives-conformance ===

## User Acceptance

- None.

## Guardrails

- Do not mutate values aliased by another expression.
- Do not convert invalid paths into silent no-ops except where jq specifies that behavior.
- Do not bypass the path depth limit.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Deletion-And-Assignment.md ===
# FEATURE: Deletion And Assignment

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines jq deletion, plain assignment, update assignment, and arithmetic assignment. |
| Depends On  | FEATURE-Path-Primitives.md, FEATURE-Arithmetic-And-Structural-Operators.md, FEATURE-Boolean-And-Alternative-Operators.md |
| Provides    | del, =, |=, +=, -=, *=, /=, %=, //= |
| Consumes    | Path primitives, arithmetic operators, generator evaluation |

## Questions

- None.

## Purpose

Implement jq's immutable path-based mutation operators and deletion behavior.

## Implementation Requirements

- Implement `del(path-expression)`.
- Implement plain assignment with all values produced by the right-hand side.
- Implement update assignment using the selected path value as the update input.
- Implement arithmetic and defined-or assignment operators.
- Support multiple paths and generator-valued left-hand sides.
- Delete paths when an update expression produces `empty`.
- Preserve the original input for sibling expressions evaluated after an assignment.
- Use the first update result for `|=` as specified.

## Programmatic Acceptance

=== AC deletion-assignment-conformance ===
Intent: The authoritative corpus slice covering deletion and assignment operators executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

select = r"=|\|=|\+="
result = subprocess.run(
    [sys.executable, "sources/run_conformance.py", "--select", select, "--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 deletion-assignment-conformance ===

## User Acceptance

- None.

## Guardrails

- Treat jq values as immutable.
- Do not apply plain-assignment RHS filters to the selected path value.
- Do not use the last update result for `|=`.
- Do not leak mutations into sibling outputs or later evaluations of the original input.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Complex-Assignment-Edges.md ===
# FEATURE: Complex Assignment Edges

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines edge-case behavior for iterated, empty, fractional, invalid, and deep assignments. |
| Depends On  | FEATURE-Deletion-And-Assignment.md, FEATURE-Path-Primitives.md |
| Provides    | Iterated path assignment, empty-update deletion, array expansion, assignment depth protections |
| Consumes    | Assignment operators, path primitives |

## Questions

- None.

## Purpose

Complete assignment semantics for complex path expressions and adversarial boundary cases.

## Implementation Requirements

- Apply assignments across iterated and multi-path selections in generator order.
- Treat an update producing `empty` as deletion.
- Expand arrays with `null` values when setting beyond their current length.
- Handle negative, fractional, NaN, and out-of-range indexes according to jq semantics.
- Reject invalid string updates and invalid array path components with runtime errors.
- Enforce assignment path depth limits.
- Preserve partial output behavior when a later assignment fails.

## Programmatic Acceptance

=== AC complex-assignment-conformance ===
Intent: The authoritative corpus slice covering complex assignment edge cases executes and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

select = r"negative|NaN|depth|empty"
result = subprocess.run(
    [sys.executable, "sources/run_conformance.py", "--select", select, "--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 complex-assignment-conformance ===

## User Acceptance

- None.

## Guardrails

- Do not silently clamp invalid assignment indexes when jq specifies an error.
- Do not discard valid outputs produced before a later runtime failure.
- Do not exceed configured path depth limits through recursive or iterated assignments.

=== END ARTIFACT ===