ras-commander: Skill for Claude Code

.claude/skills/hecras_parse_geometry/SKILL.md

hecras_parse_geometry is a skill for Claude Code from gpt-cmdr/ras-commander. It costs 141 tokens per session (3,056 once invoked), scanned A, original, MIT.

A Python tool for reading and changing HEC-RAS geometry text files. HEC-RAS is software used to model how water flows through rivers and flood areas, and these files describe river shapes and structures.

In plain words
What is it for?
Listing and filtering cross sections, reading station-and-elevation profiles, finding bank stations, updating roughness values, and extracting data for bridges, culverts, storage areas, and other structures.
Why use it?
The files use fixed-width FORTRAN formatting, which is difficult to edit safely by hand. The tool provides structured access to geometry data such as cross sections and roughness values.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: mentions AGENTS.md.

This is gpt-cmdr/ras-commander's own configuration. It tells Claude Code how to work on ras-commander itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything ras-commander configures →

Reuse

Borrowing it

Nothing to install: this file belongs to gpt-cmdr/ras-commander. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/gpt-cmdr/ras-commander/main/.claude/skills/hecras_parse_geometry/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/gpt-cmdr/ras-commander

Made for: Claude Code.

Wrote this? Show the measurements

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agentmods badge for hecras_parse_geometry

README.md
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<a href="https://agentmods.dev/skills/gpt-cmdr/ras-commander/hecras_parse_geometry"><img src="https://agentmods.dev/badge/skills/gpt-cmdr/ras-commander/hecras_parse_geometry.svg" alt="Measured on agentmods" height="20"></a>
Per session 141 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,056 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00141 $0.03056
Opus 5 $0.00071 $0.01528
Sonnet 5 $0.00028 $0.00611
Haiku 4.5 $0.00014 $0.00306

Measured 8d ago against content hash e2d0423bf87e, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

hecras_parse_geometry scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 8d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.claude/skills/hecras_parse_geometry/SKILL.md · 401 lines

How it starts

The opening of the file, as written. The whole thing — 401 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Parsing HEC-RAS Geometry Files

Primary Sources (read these for details):

  • Implementation guide: ras_commander/geom/AGENTS.md (parsing algorithms, API reference)
  • Working examples: examples/201_1d_plaintext_geometry.ipynb and examples/202_2d_plaintext_geometry.ipynb (comprehensive demonstrations)

Follow these quick-reference patterns for common tasks. Read the primary sources above for implementation details, parsing algorithms, and complete API documentation.

Quick Start Patterns

List Cross Sections

from ras_commander.geom.GeomCrossSection import GeomCrossSection

# List all cross sections in file
xs_df = GeomCrossSection.get_cross_sections("model.g01")
# Returns: DataFrame with River, Reach, RS, NodeName

# Filter by river/reach
xs_df = GeomCrossSection.get_cross_sections(
    "model.g01",
    river="Ohio River",
    reach="Reach 1"
)

Read Cross Section Geometry

# Get station-elevation profile
df = GeomCrossSection.get_station_elevation(
    "model.g01",
    "Ohio River",
    "Reach 1",
    "1000"
)
# Returns: DataFrame with Station, Elevation columns

# Get bank stations
banks = GeomCrossSection.get_bank_stations(
    "model.g01",
    "Ohio River",
    "Reach 1",
    "1000"
)
# Returns: dict with BankLeft, BankRight keys

Modify Cross Section

# Read current geometry
df = GeomCrossSection.get_station_elevation(
    "model.g01",
    "Ohio River",
    "Reach 1",
    "1000"
)

# Modify elevations (e.g., lower channel 2 feet)
df.loc[df['Station'].between(100, 200), 'Elevation'] -= 2.0

# Get bank stations
banks = GeomCrossSection.get_bank_stations(
    "model.g01",
    "Ohio River",
    "Reach 1",
    "1000"
)

# Write back (creates .bak backup, handles bank interpolation)
GeomCrossSection.set_station_elevation(
    "model.g01",
    "Ohio River",
    "Reach 1",
    "1000",
    df,
    bank_left=banks['BankLeft'],
    bank_right=banks['BankRight']
)

Update 2D Manning's n

from ras_commander.geom.GeomLandCover import GeomLandCover

# Read land cover table
lc_df = GeomLandCover.get_base_mannings_n("model.g01")
# Returns: DataFrame with LandCoverID, ManningsN

# Modify roughness
lc_df.loc[lc_df['LandCoverID'] == 42, 'ManningsN'] = 0.15

# Write back (creates .bak backup)
GeomLandCover.set_base_mannings_n("model.g01", lc_df)

Read the full file on GitHub · 401 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 8d ago First seen · 401 lines · 141 tokens per session scan A e2d0423bf87e

Subscribe to this mod's changes

hecras_parse_geometry is a skill published in the GitHub repository gpt-cmdr/ras-commander (79 stars, last pushed yesterday), licensed MIT. It adds 141 tokens to every session and 3,056 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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