dco

A guide for adding missing Developer Certificate of Origin sign-offs to Git commits. A sign-off is a “Signed-off-by” line confirming the contributor's declaration for the submitted code.

In plain words
What is it for?
Use it to fix the latest unsigned commit, recover older unsigned commits with rebase or cherry-pick, and safely update the remote branch.
Why use it?
It helps unblock pull requests when a repository check rejects commits without the required sign-off.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/linuxfoundation/lfx-self-serve/dco
Any agent
npx skills add linuxfoundation/lfx-self-serve --skill dco
Clone the repo
git clone --depth 1 https://github.com/linuxfoundation/lfx-self-serve

Made for: Claude Code, Codex.

Per session 88 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 749 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00088 $0.00749
Opus 5 $0.00044 $0.00375
Sonnet 5 $0.00018 $0.00150
Haiku 4.5 $0.00009 $0.00075

Measured 3d ago against content hash 1c9151307326, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

dco 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 3d 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/dco/SKILL.md · 85 lines

How it starts

The opening of the file, as written. The whole thing — 85 lines — stays where its author put it; the contents beside it link to each section on GitHub.

DCO Sign-off Recovery

All commits in this repo must carry a Signed-off-by: trailer (Developer Certificate of Origin). The Probot DCO check on PRs blocks merge until every commit is signed.

The standard way to add it is with --signoff at commit time. This skill handles the cases where that was missed.

Case 1: Last commit only

git commit --amend --signoff -S --no-edit
git push --force-with-lease

--force-with-lease is preferred over plain --force — it refuses if someone else has pushed to the branch since you last fetched.

Case 2: Older commit on the same branch

Find the commit hash of the oldest unsigned commit:

git log --pretty='%h %s %(trailers:key=Signed-off-by,valueonly)' origin/main..HEAD
# Any line with an empty trailing field is unsigned

Then interactively rebase from one commit before that:

git rebase -i <parent-of-unsigned-commit>
# In the editor, change `pick` to `edit` for each unsigned commit
# Save and exit; the rebase stops at each `edit` line so you can amend

For each commit in the rebase, replace it with a signed version:

git commit --amend --signoff -S --no-edit
git rebase --continue

When done, force-push:

git push --force-with-lease

Case 3: Cherry-pick / merge brought in unsigned commits

When cherry-picking commits authored by others (or your own older commits) without --signoff, the picked commits won't carry the trailer.

Cherry-pick with sign-off baked in:

git cherry-pick --signoff <sha>

If you already cherry-picked without it, fall back to Case 1 or Case 2 above.

Verifying the whole branch

Before pushing, verify every commit ahead of origin/main has both DCO and GPG:

git log --format='%G? %(trailers:key=Signed-off-by,valueonly,separator=%x20) %h %s' origin/main..HEAD

Each line must start with G or U (good GPG signature) AND carry a non-empty Signed-off-by value before the SHA. Codes N / B / E need investigation. See .claude/rules/commit-workflow.md for the canonical signing policy.

Read the full file on GitHub · 85 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. 3d ago First seen · 85 lines · 88 tokens per session scan A 1c9151307326

Subscribe to this mod's changes

dco is a skill published in the GitHub repository linuxfoundation/lfx-self-serve (11 stars, last pushed 3d ago), licensed MIT. It adds 88 tokens to every session and 749 once invoked, about $0.0004 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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