Skill/prompt-template library: let schedules (and zones/sessions) reference a reusable skill file as their prompt

[aminghadersohi]

Summary

Introduce a first-class skill / prompt-template library in Agor, and let multiple surfaces consume it — starting with schedules, which today can only take an inline prompt.

This unifies three feature requests Amin filed together on 2026-07-26:

1. Schedules pick a skill file as their prompt (this issue's driving example)
   — session
2. A list of skills per session that map to .md files somewhere (e.g. skills/)
   — session
3. Select most-used prompts per session (reuse a prompt without retyping)
   — session

All three want the same primitive: a reusable, named prompt/skill that lives in a known place and can be pointed at, instead of copy-pasted.

Problem

A schedule (agor_schedules_create) requires an inline prompt — a literal Handlebars template string. The only file hook is agentic_tool_config.context_files, which loads context, not the prompt. So there's no way to say "run skill X on this cron" without pasting the entire skill body into the schedule, and duplicating it every time the skill changes.

Zone triggers already have "prompt templates" — a second, parallel place prompts live. And there's no shared registry backing either.

Proposed design

A single skill/prompt-template registry, consumed by several surfaces:

• Registry: named skills/prompt-templates backed by .md files (branch skills/ dir and/or DB-backed Knowledge docs). Each has an id, name, and Handlebars body.
• prompt_source on schedules (and zones): instead of a bare prompt string, accept
  prompt_source: { type: "inline" | "skill", ref } — inline keeps today's behavior; skill resolves the referenced skill's markdown at fire time (so edits to the skill propagate to future runs automatically).
• Session creation UI: a picker of skills / recently-used prompts (covers requests daemon errored on claude 1, requires claude 2  #2 and Fix rename board #3).
• Zone prompt-templates become just another consumer of the same library rather than a separate concept.

Driving example

As a user, I want a daily schedule whose prompt is skills/watchtower.md, so that when I improve the skill the scheduled run picks it up without me re-editing the cron.

Notes / open questions

• Source of truth for skills: branch filesystem (skills/*.md), Knowledge docs, or both? Assistant framework already uses skills/ on the branch; leaning toward supporting both with a common resolver.
• Portability across agents: claude-code has native /skill invocation, but a skill-file reference is agent-agnostic — preferred so codex/gemini/etc. schedules work too.
• Design the three requests together to avoid building three overlapping half-versions.

Filed by the Agor orchestrator assistant on behalf of Amin (Slack #agor).

[mistercrunch]

Similar to other recent issue filed, but wondering if you can just autocomplete and reference a repo file or knowledge articles, like the prompt can just say "run prompts/cleanup.md" or "run agor://my-knowledge-namespace/prompts/my-routine.md"