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.
npx agentmods add skills/dean0x/devflow/regressionnpx skills add dean0x/devflow --skill regressiongit clone --depth 1 https://github.com/dean0x/devflowWhat 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 | $0.00023 | $0.01012 |
| Opus 5 | $0.00012 | $0.00506 |
| Sonnet 5 | $0.00005 | $0.00202 |
| Haiku 4.5 | $0.00002 | $0.00101 |
Grade A, and why
regression 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 yesterday.
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 — 147 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Regression Patterns
Domain expertise for detecting functionality regressions and validating implementation intent. Use alongside devflow:review-methodology for complete regression reviews.
Iron Law
WHAT WORKED BEFORE MUST WORK AFTER
Every change carries regression risk. Removed exports break consumers. Changed signatures break callers. Modified behavior breaks expectations. The burden of proof is on the change: demonstrate no regression, or document the intentional breaking change.
Regression Categories
1. Lost Functionality
Features, exports, or capabilities that existed before but are missing after.
| Type | Risk | Detection |
|---|---|---|
| Removed exports | Breaks consumers | Compare export statements |
| Removed CLI options | Breaks scripts | Compare option definitions |
| Removed API endpoints | Breaks clients | Compare route handlers |
| Removed event handlers | Breaks integrations | Compare .on() calls |
// VIOLATION: Export removed without deprecation
// BEFORE: export function deleteUser(id: string): void { }
// AFTER: (removed) - consumers will break!
2. Broken Behavior
Code still exists but behaves differently in breaking ways.
| Type | Risk | Detection |
|---|---|---|
| Changed return types | Null dereference | Compare function signatures |
| Changed defaults | Unexpected behavior | Compare default values |
| Removed side effects | Missing events/logs | Compare emit/log calls |
| Changed error handling | Uncaught errors | Compare throw/return patterns |
// VIOLATION: Return type widened without migration
// BEFORE: function getUser(id: string): User { }
// AFTER: function getUser(id: string): User | null { }
// Callers assuming non-null will break!
3. Intent vs Reality Mismatch
Commit message promises one thing, code does another.
| Type | Risk | Detection |
|---|---|---|
| Commit says X, code does Y | False confidence | Compare message to diff |
| Partial implementation | Incomplete feature | Check all stated changes |
| Missing edge cases | Fragile code | Verify claimed coverage |
What ships with it
3 files 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.
- yesterday First seen · 147 lines · 23 tokens per session scan A 9ba81ef5f670
regression is a skill published in the GitHub repository dean0x/devflow (19 stars, last pushed yesterday), licensed MIT. It adds 23 tokens to every session and 1,012 once invoked, about $0.0001 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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