The CLI skill had grown to 20.8 KB of command tables and flag catalogs that
`bsk --help` already answers at runtime, so every agent paid for them on every
task. Rewrite both skills around the durable rules an agent cannot rediscover
-- session lifecycle, the observe/act/observe loop, the Agent Window boundary,
and the stop-on-success contract -- and delegate flag details to the CLI's own
help output. The CLI skill drops to 6.9 KB (-67%) and the DSH skill to 5.1 KB.
Keep the parts that help discovery has no answer for: the literal
`[hover first: ...]` observation marker, the `request-help` outcome values, the
complete command-name inventory, and the required flags agents guess wrong
(`fill --value`, `select --value`, `screenshot --out`, `emulate --device`).
Also bind `--no-focus` explicitly to `bsk session start`, since a bare mention
led agents to pass it to `bsk navigate`.
Validated with 36 agent runs of the `core` eval suite against a real browser,
comparing the old and new instructions with everything else held constant.
Pass rate did not regress (the lean version was better on `form-controls`) and
token cost per task came out even. The inventory and flag signatures cut
`--help` round-trips from 1.7 to 0.7 per task and removed the invented
`bsk back` / `bsk forward` calls the first draft produced.
Tighten the DSH size assertion to a range so the budget is bounded from both
sides and accidental truncation fails the test.
Co-authored-by: Cursor <cursoragent@cursor.com>
Register bundled browser instructions at agent scope, prioritize foreground commands over thumbnail capture, and unify cancellation and session cleanup.
The plugin exposed only tools; the BrowserSkill agent skill never reached
the harness's <available_skills> catalog. Register it as an embedded runtime
skill (progressive disclosure: catalog entry resident, body on skill-tool
invocation) via the official ctx.skills seam — silent no-op when the
composition lacks it.
Content is build-time assembled so there is one source of truth:
skill/prelude.md (committed, dsh-specific: tool<->CLI map, owned-session
semantics, plugin-only overrides) + the canonical repo-root skill/SKILL.md
verbatim (the same file crates/bsk-cli/build.rs mirrors; frontmatter
stripped, name/description supplied by the registration). Generated into
src/skill-content.generated.ts (gitignored) — registration and every
pre-step snapshot are pure in-memory reads: no disk, no process, no daemon.
Scripts: build:skill chained into build/test/typecheck (same pattern as
build:css); biome excludes the generated artifacts. Tests: +3 (catalog
content, in-memory weight, silent degradation). 116/116 green.
