=== BEGIN ARTIFACT ARCHITECTURE.md ===
# ARCHITECTURE: jq

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines the modular standard-library architecture for a standalone jq interpreter. |
| Depends On  |  |
| Provides    | interpreter architecture, executable boundary, generator evaluation model |
| Consumes    |  |

## Questions

- None.

## Architecture

The implementation is a modular Python interpreter with an executable `jq` entry point. The runtime is divided into:

- CLI and process boundary: argument handling, JSON input decoding, compact output, diagnostics, and exit codes.
- Lexer: jq tokens, comments, literals, identifiers, fields, bindings, delimiters, and formats.
- Parser: precedence-aware AST construction, declarations, control syntax, patterns, and compile diagnostics.
- Value model: immutable JSON-compatible values, numeric literals, NaN, and infinities.
- Evaluator: ordered generator execution, backtracking, scopes, errors, labels, and assignments.
- Builtins: arithmetic, collections, strings, regular expressions, dates, paths, I/O, and streaming.

All runtime code uses Python's standard library. No system jq executable, third-party jq implementation, package, network service, or external runtime dependency is permitted.

### Ownership boundaries

| Area | Owner | Boundary |
|---|---|---|
| CLI and serialization | executable/process modules | Owns stdin, stdout, stderr, and process status |
| Lexing and parsing | lexer/parser modules | Produces executable AST or equivalent |
| Values | value module | Owns numeric and immutable value behavior |
| Evaluation | evaluator module | Owns generator ordering, scopes, errors, and control flow |
| Builtins | builtin/runtime modules | Operates through evaluator and value interfaces |
| Conformance assets | `sources/` | Read-only external test and specification assets |

The evaluator must expose generator semantics rather than scalar function semantics: each filter consumes one input and may produce zero, one, or many ordered outputs.

## Technology Stack

- Python 3.11 or newer, standard library only, for the interpreter and acceptance checks.
- POSIX `sh` for the supplied conformance entry point.

## Programmatic Acceptance

=== AC architecture-runtime ===
Intent: The architecture establishes an executable Python runtime boundary.
import os
import subprocess
import sys

result = subprocess.run(
    [os.path.join(os.getcwd(), "jq"), "-c", "."],
    input="null\n",
    capture_output=True,
    text=True,
)
print(result.stdout)
print(result.stderr, file=sys.stderr)
assert result.returncode == 0
=== END AC architecture-runtime ===

=== AC architecture-stdlib ===
Intent: The architecture runs with the declared Python standard-library runtime.
import sys

assert sys.version_info >= (3, 11)
import argparse
import base64
import dataclasses
import datetime
import decimal
import itertools
import json
import math
import re
=== END AC architecture-stdlib ===

## User Acceptance

- None.

## Guardrails

- Do not shell out to jq.
- Do not use third-party packages or bindings.
- Preserve generator ordering, multiplicity, backtracking, and partial output.
- Keep `sources/` read-only.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Executable-Entry-Point.md ===
# FEATURE: Executable Entry Point

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Provides the executable jq command and its fixed compact filter interface. |
| Depends On  | ARCHITECTURE.md |
| Provides    | executable jq, -c filter invocation |
| Consumes    | interpreter architecture, JSON input stream |

## Questions

- None.

## Intent

The application root contains an executable named `jq`. It accepts `-c '<program>'`, reads JSON values from standard input, evaluates the supplied filter, and writes each generated value as one compact JSON value per line.

## Programmatic Acceptance

=== AC exec-entrypoint ===
Intent: The executable entry point runs the corpus's primitive interface cases.
import json
import os
import subprocess
import sys

result = subprocess.run(
    [sys.executable, "sources/run_conformance.py", "--select", r"^(true|false|null|1)$", "--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 exec-entrypoint ===

=== AC exec-interface ===
Intent: The executable accepts the declared compact command-line interface and completes successfully.
import os
import subprocess

payload = "null\n"
result = subprocess.run(
    [os.path.join(os.getcwd(), "jq"), "-c", "."],
    input=payload,
    capture_output=True,
    text=True,
)
print(result.stdout)
print(result.stderr, file=__import__("sys").stderr)
assert result.returncode == 0
assert result.stdout.splitlines()
=== END AC exec-interface ===

## User Acceptance

- None.

## Guardrails

- The executable must be named `jq` and located at the application root.
- `-c` is the only exercised option.
- Output must contain one compact JSON value per line.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Process-Contract.md ===
# FEATURE: Process Contract

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Defines jq compilation, runtime failure, success, and diagnostic exit behavior. |
| Depends On  | FEATURE-Executable-Entry-Point.md, FEATURE-Declarations-And-Control-Syntax.md, FEATURE-Errors-And-Optional-Evaluation.md |
| Provides    | compile exit 3, runtime exit 5, success exit 0, stderr diagnostics |
| Consumes    | executable jq, parser, evaluator |

## Questions

- None.

## Intent

Compilation failures return exit code `3`. Runtime failures return exit code `5`. Successful completion returns `0`. Diagnostics are written to standard error, and values emitted before a runtime failure remain on standard output.

## Programmatic Acceptance

=== AC process-contract-compile ===
Intent: Invalid jq programs are rejected with the compile-failure status.
import os
import subprocess

result = subprocess.run(
    [os.path.join(os.getcwd(), "jq"), "-c", "{"],
    input="null\n",
    capture_output=True,
    text=True,
)
print(result.stdout)
print(result.stderr, file=__import__("sys").stderr)
assert result.returncode == 3
=== END AC process-contract-compile ===

=== AC process-contract-runtime ===
Intent: A valid jq program that raises at runtime returns the runtime-failure status.
import os
import subprocess

result = subprocess.run(
    [os.path.join(os.getcwd(), "jq"), "-c", "error"],
    input="null\n",
    capture_output=True,
    text=True,
)
print(result.stdout)
print(result.stderr, file=__import__("sys").stderr)
assert result.returncode == 5
=== END AC process-contract-runtime ===

=== AC process-contract-partial-output ===
Intent: Runtime failure preserves values emitted before the failure.
import os
import subprocess

result = subprocess.run(
    [os.path.join(os.getcwd(), "jq"), "-c", "1, error"],
    input="null\n",
    capture_output=True,
    text=True,
)
print(result.stdout)
print(result.stderr, file=__import__("sys").stderr)
assert result.returncode == 5
assert result.stdout.splitlines()
=== END AC process-contract-partial-output ===

## User Acceptance

- None.

## Guardrails

- Compile and runtime failures must remain distinguishable.
- Diagnostics must never be required on stdout.
- Do not discard partial output before a runtime error.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-JSON-IO-BoundARY.md ===
# FEATURE: JSON I/O Boundary

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Handles JSON input streams and compact output serialization for jq values. |
| Depends On  | ARCHITECTURE.md, FEATURE-Executable-Entry-Point.md, FEATURE-Value-Model.md |
| Provides    | JSON stdin decoding, compact JSON line serialization, Unicode and special-number handling |
| Consumes    | executable jq, JSON value model |

## Questions

- None.

## Intent

The process boundary decodes each JSON input value supplied on standard input and serializes every generated result compactly, preserving order and the value distinctions required by the conformance harness.

## Programmatic Acceptance

=== AC json-boundary ===
Intent: JSON boundary behavior passes the corpus cases covering primitive input and output serialization.
import json
import os
import subprocess
import sys

result = subprocess.run(
    [sys.executable, "sources/run_conformance.py", "--select", r"^(true|false|null|1)$", "--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 json-boundary ===

=== AC json-order ===
Intent: Multiple input values and generated outputs preserve stream order.
import json
import os
import subprocess

payload = "1\n2\n"
result = subprocess.run(
    [os.path.join(os.getcwd(), "jq"), "-c", "."],
    input=payload,
    capture_output=True,
    text=True,
)
print(result.stdout)
print(result.stderr, file=__import__("sys").stderr)
assert result.returncode == 0
actual = [json.loads(line) for line in result.stdout.splitlines()]
expected = [1, 2]
assert actual == expected
=== END AC json-order ===

## User Acceptance

- None.

## Guardrails

- Emit compact JSON values one per line.
- Preserve output order and multiplicity.
- Do not alter supplied conformance assets.
=== END ARTIFACT ===
=== BEGIN ARTIFACT FEATURE-Lexer.md ===
# FEATURE: Lexer

| Field       | Value |
|-------------|-------|
| Version     | 20260822 V1 |
| Description | Tokenizes jq source into keywords, literals, identifiers, operators, and delimiters. |
| Depends On  | ARCHITECTURE.md |
| Provides    | jq tokens, comments, delimiters, identifiers, fields, literals, bindings |
| Consumes    | interpreter architecture |

## Questions

- None.

## Intent

The lexer recognizes jq keywords, identifiers, fields, variable bindings, numeric and string literals, operators, comments, formats, delimiters, and the state transitions required by interpolation and nested expressions.

## Programmatic Acceptance

=== AC lexer-corpus ===
Intent: Lexer-focused primitive and literal cases execute successfully through the supplied conformance runner.
import json
import os
import subprocess
import sys

result = subprocess.run(
    [sys.executable, "sources/run_conformance.py", "--select", r"^(true|false|null|1|\.)$", "--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 lexer-corpus ===

=== AC lexer-comments ===
Intent: The lexer accepts comments and ignores them outside string literals.
import os
import subprocess
import sys

result = subprocess.run(
    [os.path.join(os.getcwd(), "jq"), "-c", "1 # comment"],
    input="null\n",
    capture_output=True,
    text=True,
)
print(result.stdout)
print(result.stderr, file=sys.stderr)
assert result.returncode == 0
assert result.stdout.splitlines()
=== END AC lexer-comments ===

## User Acceptance

- None.

## Guardrails

- Invalid characters and malformed tokens must produce compile failure.
- Comment handling must not consume string contents.
- Nested delimiters and interpolation state must remain balanced.
=== END ARTIFACT ===