lintle

Validate and clean Two-Line Element (TLE) satellite corpora — correctness-first.

lintle audits TLE files exported from space-track.org against the standardized TLE spec, repairs the systematic export defects, and emits a uniform, de-defected corpus that any SGP4 / orbital-mechanics library can ingest directly. Records it cannot safely repair are quarantined — never silently mangled — into a per-file sidecar detailed enough to file a defect report with space-track.

• Correctness over recovery — every emitted record is re-validated and valid by construction; on any doubt a record is quarantined, never guessed.
• Constant memory — streams a 3 GB file line-by-line; the whole ~30 GB corpus never loads into RAM.
• Byte-deterministic output — same input → identical bytes every run (diff-able, CI-friendly).

On the bundled 29-file corpus (~232 M records): 99.96 % cleaned, 0.044 % quarantined — every quarantined record fell into an anticipated defect category.

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What problem it solves

A TLE record is two fixed-width lines, each exactly 69 ASCII columns, with a mod-10 checksum in column 69. Bulk historical exports from space-track carry two systematic, era-specific defects:

• Trailing \ artifact — almost every Line 1 has an extra \ byte appended before the newline.
• Missing checksum digit — many records were exported without their column-69 checksum, leaving 68-column lines.

These appear independently and in combination, and a small fraction of records are genuinely corrupt (garbled columns, orphaned lines, wrong lengths). lintle distinguishes the safely-repairable from the genuinely-corrupt and treats each correctly.

Installation

Requires Python 3.14+ and uv. The only runtime dependency is rich (>=15,<16, terminal rendering for the clean progress UI); everything else is standard library. (sgp4 is a dev-only test oracle.)

uv sync

No build step is needed to run the tool.

Usage

The console script is lintle (python -m lintle … is equivalent):

# Produce cleaned output + quarantine sidecars
uv run lintle clean [path]

# Re-render a prior clean run's aggregate summary from its report.json
uv run lintle report [out-dir]

# Explain a rule ID or fix tag — definition, examples, source citation
uv run lintle explain <TAG>

# Compare two clean runs' findings (per-rule deltas)
uv run lintle diff <run-a> <run-b>

Arguments and options:

Option	Default	Meaning
path	data/source	A single file or directory. A directory is globbed for tle*.txt (tool output *.cleaned.txt / *.broken.txt is excluded).
--out-dir DIR	data/output	Where clean writes its output. Created if absent.
--jobs N	CPU count − 1	Files processed in parallel. Lower it if a slow disk causes I/O contention.
--report text|json	text	Summary format.
--max-quarantined N[%]	0	Exit non-zero only if MORE than N records were quarantined; or, with a trailing %, more than N% of routed records (clean + quarantined). Default 0 ≡ "any quarantine fails".
--resume / --no-resume	—	(clean only) Resume an interrupted run without prompting / ignore any checkpoint and start fresh. See Cancelling and resuming.

Examples:

# Clean the whole corpus
uv run lintle clean data/source

# Clean one file to a custom location
uv run lintle clean data/source/tle2022.txt --out-dir data/output

# Clean the corpus, capture a machine-readable summary
uv run lintle clean data/source --report json > run-summary.json

# CI gate: fail only if more than 100 records (or 1% of routed records) are quarantined
uv run lintle clean data/source --max-quarantined 100 --report json > run-summary.json
uv run lintle clean data/source --max-quarantined 1%  --report json > run-summary.json

# Look up what a rule ID or fix tag means, with a verified example
uv run lintle explain TLE-CHK-001
uv run lintle explain reconstructed-checksum

Exit codes:

Code	Meaning
0	Quarantine count (or rate) is at or below --max-quarantined (default 0).
1	Quarantine count (or rate) exceeded --max-quarantined.
2	Operational error — no input files, disk shortfall, lock held, stale/corrupt/declined resume, or a file that failed to process.
129 / 130 / 143	Killed by SIGHUP / Ctrl-C (SIGINT) / SIGTERM.

Repairable defects (including the near-universal trailing \) do not raise the exit code above 0 — almost every raw file contains them. --max-quarantined preserves the meaningful 2 (operational error) and 130 (Ctrl-C) signals that a lintle … || true pipe would swallow.

Correctness guarantees & limits

This is the heart of the tool. The cleaner never applies a fix and hopes: it applies a candidate fix, re-runs the full validator, and commits only if the result passes — so the output cannot contain a wrong-but-valid-looking record. One validator (tle.py) defines what "perfect" means; clean checks every candidate repair against it before committing — so correctness is structural, not assumed.

lintle never invents data. The single sanctioned reconstruction is the column-69 checksum — safe only because it is a deterministic mod-10 function of columns 1–68, so recomputing a missing one asserts nothing the record didn't already say (the redundancy paradox: the only field safe to rebuild is the one that was redundant to begin with). A mod-10 checksum accepts a wrong line 1-in-10 times by luck, so guessing an orbital-data character risks a record that looks valid but is silently wrong — the one outcome worse than dropping it. So anything requiring such a guess (bad checksum, wrong length, orphan line, garbled columns) is quarantined, not repaired.

Fixes fall into five classes in decreasing order of safety — content-preserving (trailing \, CRLF, trailing whitespace), reconstructed-checksum, content-shifting (leading trim), structural (drop blanks), and corrupt (quarantine).

→ Full fix-class table, repair tiers, and the stable rule registry: ARCHITECTURE.md §1 and §4.

Output

A clean run lays --out-dir out like this:

<out-dir>/
├── cleaned/                tleYYYY.cleaned.txt   — one per input file
├── broken/                 tleYYYY.broken.txt    — one per input file
├── broken-noradids.ndjson  — corpus-wide list of quarantined NORAD IDs
├── report.jsonl            — corpus-wide structured findings stream
└── report.md               — corpus-wide run report

• cleaned/tleYYYY.cleaned.txt — standard 2-line TLE text, every record verified valid and ready for downstream ingestion.
• broken/tleYYYY.broken.txt — the quarantine sidecar: source line number(s), a human-readable reason, and the offending line(s) copied byte-faithfully, with a header formatted to paste into a space-track defect report.
• broken-noradids.ndjson — one {"noradId":N} per line, the deduplicated, sorted set of NORAD catalog numbers quarantined anywhere in the run (for programmatic consumers).
• report.md — human-readable run report: corpus totals, % cleaned/quarantined, fix counts, the per-rule defect breakdown, a per-file table, and a per-NORAD breakdown.
• report.json — the machine-readable run envelope, byte-identical to the --report json stdout output. Persisted on every clean run so lintle report can re-render the summary later without re-processing the corpus.

At the end of a clean run an aggregate summary panel is rendered to stderr — corpus totals, % cleaned/quarantined, and the top fix / quarantine rules — sized to the terminal width (with an ASCII-bar fallback off a TTY). Text-mode stdout stays empty; the full machine summary is report.json (or --report json on stdout). records counts paired 2-line entries; clean are those that passed and were written; quarantined is everything routed to broken/ (failed records and every orphan line). The invariant is records + orphan == clean + quarantined. Defects key by the stable RuleID registry (TLE-CHK-001, TLE-PAIR-001, …) so one identifier names a defect across every artifact.

lintle report [out-dir] re-renders that panel to stdout from a prior run's report.json (or echoes the JSON verbatim with --report json); a missing or unreadable report.json exits 2.

Live progress during a long run is also written to stderr (so it never pollutes the stdout --report json pipe): a size roster up front, per-file byte/record progress with throughput and ETA, and an [k/N] line as each file finishes.

→ Machine-readable contracts (--report json envelope, report.jsonl, the .broken.txt format, the checkpoint): ARCHITECTURE.md §6.

Results on the bundled corpus

A full run over the 29-file corpus (tle2004–tle2025, ~232 million records):

• 99.96 % cleaned — 187.9 M trailing-\ artifacts stripped, 71.3 M missing checksums reconstructed.
• 0.044 % quarantined (103,228 records) as genuinely corrupt — every quarantined record fell into an anticipated category; no unknown defect type surfaced.

Operational notes

Cancelling and resuming

A long clean can be interrupted (Ctrl-C, a closed laptop, SIGTERM/SIGHUP). Re-run the same command (same --out-dir, unchanged inputs) to resume; on a TTY it prompts, in CI it auto-resumes. Resume granularity is a whole file: completed files are skipped and the file in flight at the interruption restarts from the beginning — so a multi-file corpus run benefits, but a single-file run gains nothing. --no-resume discards the checkpoint and starts fresh (clearing prior outputs).

→ Checkpoint shape and the resume-decision matrix: ARCHITECTURE.md §5.

Disk space

Every record is routed to exactly one of cleaned/ or broken/ — never duplicated — so the output is roughly the input's size plus tiny metadata. As a guard, lintle requires ~2× the total input size free on the --out-dir volume before starting, aborting with exit 2 if short (and warning on stderr in the 2×–2.5× borderline band). Rule of thumb for the ~30 GB corpus: keep ~60 GB free to clear the abort floor, ~75 GB to clear the warning. (The 12 GB TLEs.zip is not an input and is never read.)

Development

uv sync                          # install dev dependencies
uv run pytest                    # run the test suite
uv run pytest --cov=lintle       # with a coverage report
uv run ruff check                # lint
uv run ruff format               # auto-format

The suite includes per-module unit tests, an asymmetric cross-check against the trusted sgp4 parser (a known-good TLE must be accepted by both), and end-to-end integration tests (golden output, idempotence, re-validation). See CONTRIBUTING.md for setup, testing, and the git workflow.

Further reading

ARCHITECTURE.md is the living design reference — the validator definition, the module map and data flow, the repair model, streaming/durability/resume, the machine-readable output-format contracts, and the runtime-dependency policy. Dated design specs, plans, and corpus-run summaries are kept for historical rationale under docs/superpowers/archive/.