Getting it into your agent
This one installs as part of its plugin. Adding the marketplace and installing the plugin brings it with everything else the plugin ships.
/plugin marketplace add melodic-software/claude-code-plugins/plugin install instruction-placementWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/melodic-software/claude-code-plugins/delta)<a href="https://agentmods.dev/skills/melodic-software/claude-code-plugins/delta"><img src="https://agentmods.dev/badge/skills/melodic-software/claude-code-plugins/delta/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/melodic-software/claude-code-plugins/delta"><img src="https://agentmods.dev/badge/skills/melodic-software/claude-code-plugins/delta.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00086 | $0.03423 |
| Opus 5.5 | $0.00034 | $0.01369 |
| Sonnet 5.5 | $0.00017 | $0.00685 |
| Haiku 4.5 | $0.00009 | $0.00342 |
Grade A, and why
delta scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 18d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 225 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Arguments. [--since <ISO date>] [--noise-budget <n>]. Default: since the artifact's last run
Pre-computed context
!"${CLAUDE_PLUGIN_ROOT}/scripts/precompute.sh" audit 2>/dev/null || echo "- Orientation unavailable"
Purpose
A full audit is worth running rarely and reading carefully. This is the lane for the other times: it answers what moved, so a repeat run costs attention proportional to actual change.
The failure it prevents is specific. An audit re-run that re-presents the same forty findings the operator already worked through trains them to skim, and a skimmed report is how a bad migration gets approved. Reporting only movement keeps the signal survivable on a cadence.
Read these first
| Read | For |
|---|---|
../../context/findings-artifact.md |
Where the spine baseline and the findings artifact live, the status vocabulary, re-run merge semantics, the baseline-capture obligation, and the finding-id constituents a suppression entry is keyed by |
../../reference/consumer-config.md |
The suppression surface: its layers, its per-key merge, the policy-floor inversion, and the report obligations |
../../context/routing-rubric.md |
Only when a genuinely new candidate needs classifying |
This skill does not restate the merge semantics, the baseline's shape, the suppression entry format, or the home. Those documents own them; a second statement is a second drift.
Two inputs, two homes, and the reason they are different files
The spine baseline is the comparison input: a snapshot of the previous run's detector spine, in
the baselines/ slot the lifecycle artifact protocol names
(../../reference/artifact-protocol.md), branch-keyed, at
the home findings-artifact.md defines. Memory tier and checkout-local, which is right for it: a
spine is recomputed next run, and one from another checkout describes a tree this one lacks.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 18d ago Changed · -1 lines 751c401e55b1
- 19d ago Changed · +7 lines ce18ba1ee352
- 20d ago Changed · +2 lines 0201a5da05ce
- 21d ago Changed · -88 tokens per session 7dea016bdc80
- 1mo ago Changed d39baf7c0a90
- 1mo ago Changed · +86 lines · +22 tokens per session 61ae1763fbab
- 1mo ago Changed · +1 lines 92e78a24eb90
- 1mo ago First seen · 130 lines · 152 tokens per session scan A f7562037b376
delta is a skill published in the GitHub repository melodic-software/claude-code-plugins (26 stars, last pushed today), licensed MIT. It adds 86 tokens to every session and 3,423 once invoked, about $0.0003 per session on Opus 5.5. 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 2026-09-03.
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