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

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Provide jq destructuring patterns and fallback alternatives. |
| Depends On  | FEATURE-Variable-Bindings.md, FEATURE-Conditionals-and-Exception-Flow.md |
| Provides    | ?// destructuring alternatives |
| Consumes    | as bindings, lexical scope, try/catch |

## Questions

- None.

## Purpose

Support array and object destructuring in `as` bindings, including missing bindings and the `?//` alternative operator.

## Behavior

- Bind array elements positionally, using `null` for missing elements.
- Bind object fields by identifier, explicit key, and nested pattern.
- Support multiple alternatives separated by `?//`.
- Select the next alternative when pattern matching or subsequent evaluation raises an error.
- Expose all variables referenced by the continuation, binding unmatched variables to `null`.
- Propagate errors from the final alternative.

## Programmatic Acceptance

=== AC func-004-conformance ===
Intent: The scoped conformance corpus executes the destructuring-alternative cases owned by FUNC-004 and passes them.
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 and summary["error"] == 0
assert result.returncode == 0

=== END AC func-004-conformance ===

## User Acceptance

- None.

## Guardrails

- Do not treat a failed first pattern as a runtime failure when a later `?//` alternative can succeed.
- Do not load module fixtures while evaluating destructuring syntax.

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

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Discover jq paths and construct projections from path expressions. |
| Depends On  | FEATURE-Slices-and-Iteration.md, FEATURE-Recursive-Generators.md |
| Provides    | path, paths, and pick |
| Consumes    | accessors, iteration, recursive generators |

## Questions

- None.

## Purpose

Implement path discovery for exact and generated path expressions, filtered recursive paths, and projected values.

## Behavior

- `path(expression)` returns path arrays containing string object keys and numeric array indices.
- Exact paths are reported even when the addressed value does not yet exist.
- Generated paths report only paths that exist in the input.
- `paths` excludes the empty root path.
- `paths(filter)` returns paths whose values satisfy the filter.
- `pick(expressions)` creates a projection containing only the selected paths.
- Invalid path expressions raise runtime errors.

## Programmatic Acceptance

=== AC path-001-conformance ===
Intent: The scoped conformance corpus executes the path-discovery and projection cases owned by PATH-001 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 and summary["error"] == 0
assert result.returncode == 0

=== END AC path-001-conformance ===

## User Acceptance

- None.

## Guardrails

- Preserve path ordering and multiplicity.
- Do not confuse path values with projected values.
- Reject invalid path expressions without silently producing a path.

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

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Read, update, and delete nested jq values through path arrays. |
| Depends On  | FEATURE-Path-Discovery.md, FEATURE-Accessors.md |
| Provides    | getpath, setpath, and delpaths |
| Consumes    | path arrays, jq value model, field and index access |

## Questions

- None.

## Purpose

Implement immutable nested path operations for reading, creation, replacement, array expansion, and deletion.

## Behavior

- `getpath(path)` reads a nested value and returns `null` for an absent path where jq permits it.
- `setpath(path; value)` creates missing objects and arrays as required and replaces existing values.
- `delpaths(paths)` removes each requested path while preserving the remaining structure.
- Multiple paths are processed according to jq ordering and overlap semantics.
- Invalid path components raise runtime errors.
- Excessively deep paths are rejected according to jq depth limits.
- Operations do not mutate the original input value observed by sibling expressions.

## Programmatic Acceptance

=== AC path-002-conformance ===
Intent: The scoped conformance corpus executes the getpath, setpath, and delpaths cases owned by PATH-002 and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

select = "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 and summary["error"] == 0
assert result.returncode == 0

=== END AC path-002-conformance ===

## User Acceptance

- None.

## Guardrails

- Keep path operations immutable from the caller’s perspective.
- Do not convert invalid array/object path components into string keys.
- Enforce jq’s path-depth limits.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Assignment-Operators.md ===
# FEATURE: Assignment Operators

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Implement jq deletion and immutable assignment operators. |
| Depends On  | FEATURE-Path-Primitives.md, FEATURE-Boolean-and-Alternative-Operators.md |
| Provides    | del, =, |=, +=, -=, *=, /=, %=, and //=
| Consumes    | getpath, setpath, delpaths, path expressions |

## Questions

- None.

## Purpose

Provide jq’s path-based deletion, plain assignment, update assignment, arithmetic assignment, and defined-or assignment semantics.

## Behavior

- `del(path)` removes selected fields, elements, and slices.
- `=` evaluates its right-hand side against the original input and uses every produced value.
- `|=` evaluates its right-hand side against each selected value and uses the first result.
- Empty update results delete the selected path.
- Arithmetic assignment operators apply the corresponding binary operation to selected values.
- `//=` replaces false or null values with the right-hand result.
- Multiple selected paths preserve jq ordering and immutable-output behavior.
- Assignments can create missing nested objects and arrays where jq permits.

## Programmatic Acceptance

=== AC path-003-conformance ===
Intent: The scoped conformance corpus executes deletion and assignment-operator cases owned by PATH-003 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 and summary["error"] == 0
assert result.returncode == 0

=== END AC path-003-conformance ===

## User Acceptance

- None.

## Guardrails

- Never mutate values visible to sibling expressions.
- Preserve the distinction between plain assignment and update assignment.
- Do not swallow invalid-path or type errors.

=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Complex-Assignments.md ===
# FEATURE: Complex Assignments

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Handle jq assignment edge cases across generated and deep paths. |
| Depends On  | FEATURE-Assignment-Operators.md, FEATURE-Reductions-and-Iteration-Control.md |
| Provides    | complex assignment edge-case behavior |
| Consumes    | deletion and assignment operators, generated paths |

## Questions

- None.

## Purpose

Complete assignment semantics for iterated paths, empty updates, array expansion, invalid indices, NaN indices, and deeply nested structures.

## Behavior

- Apply assignments to all paths produced by iteration and selection expressions.
- Remove array elements or object fields when an update produces `empty`.
- Expand arrays with `null` values when assigning beyond the current end where jq permits.
- Reject invalid negative, fractional, and NaN assignment indices with jq runtime errors.
- Preserve partial output and error behavior when one generated path fails.
- Enforce depth limits for path construction and mutation.
- Maintain immutable input behavior across complex assignments.

## Programmatic Acceptance

=== AC path-004-conformance ===
Intent: The scoped conformance corpus executes complex assignment edge cases owned by PATH-004 and passes.
Suite: scoped
Requires: executable=python3; scope=test

import json
import os
import subprocess
import sys

select = "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 and summary["error"] == 0
assert result.returncode == 0

=== END AC path-004-conformance ===

## User Acceptance

- None.

## Guardrails

- Do not reinterpret invalid indices as valid object keys.
- Do not lose outputs emitted before a runtime assignment failure.
- Reject paths exceeding jq’s supported depth limits.

=== END ARTIFACT ===