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/marcus/sidecar/create-modalnpx skills add marcus/sidecar --skill create-modalgit clone --depth 1 https://github.com/marcus/sidecarWhat 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 | $0.00069 | $0.02060 |
| Opus 5 | $0.00034 | $0.01030 |
| Sonnet 5 | $0.00014 | $0.00412 |
| Haiku 4.5 | $0.00007 | $0.00206 |
Grade A, and why
create-modal 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 2d 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 — 281 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Creating Declarative Modals
Use the internal/modal package. The library handles keyboard navigation, mouse hit regions, hover states, and scrolling automatically.
Quick Start
import "github.com/marcus/sidecar/internal/modal"
// 1. Create the modal
m := modal.New("Delete Worktree?",
modal.WithWidth(58),
modal.WithVariant(modal.VariantDanger),
modal.WithPrimaryAction("delete"),
).
AddSection(modal.Text("Name: " + wt.Name)).
AddSection(modal.Spacer()).
AddSection(modal.Buttons(
modal.Btn(" Delete ", "delete", modal.BtnDanger()),
modal.Btn(" Cancel ", "cancel"),
))
// 2. Render in View
func (p *Plugin) View(width, height int) string {
background := p.renderListView(width, height)
rendered := p.myModal.Render(width, height, p.mouseHandler)
return ui.OverlayModal(background, rendered, width, height)
}
// 3. Handle input in Update
case tea.KeyMsg:
action, cmd := p.myModal.HandleKey(msg)
if action != "" {
return p.handleAction(action) // "delete", "cancel", etc.
}
return p, cmd
case tea.MouseMsg:
action := p.myModal.HandleMouse(msg, p.mouseHandler)
if action != "" {
return p.handleAction(action)
}
return p, nil
Critical: Modal Initialization Pattern
The modal must exist before input handling. Create an ensure function called in both View and Update:
func (p *Plugin) ensureMyModal() {
if p.targetItem == nil {
return // Required state missing
}
modalW := 50
if modalW > p.width-4 {
modalW = p.width - 4
}
if modalW < 20 {
modalW = 20
}
// Only rebuild if needed
if p.myModal != nil && p.myModalWidthCache == modalW {
return
}
p.myModalWidthCache = modalW
p.myModal = modal.New("Title", modal.WithWidth(modalW), ...).
AddSection(...)
}
Call ensureModal() before the nil check in key handlers:
func (p *Plugin) handleMyModalKeys(msg tea.KeyMsg) tea.Cmd {
p.ensureMyModal() // CRITICAL: Before nil check
if p.myModal == nil {
return nil
}
action, cmd := p.myModal.HandleKey(msg)
// ...
}
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.
- 2d ago First seen · 281 lines · 69 tokens per session scan A 2928d64432b8
create-modal is a skill published in the GitHub repository marcus/sidecar (1,049 stars, last pushed 2d ago), licensed MIT. It adds 69 tokens to every session and 2,060 once invoked, about $0.0003 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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