Builtin Packs

Gas City ships with a small set of built-in packs. These packs are embedded in the gc binary and served from the user-global pack cache under $GC_HOME/cache/repos/ (default ~/.gc/cache/repos/). Nothing is materialized into the city; the binary pre-seeds the cache with its own embedded content at each pack's canonical pinned commit, so the pinned imports below resolve offline.

Built-in packs are not implicit: nothing splices them into config composition at load time. They compose only through explicit pinned imports in pack.toml, which gc init writes for you:

[imports.core]
source = "https://github.com/gastownhall/gascity.git//internal/bootstrap/packs/core"
version = "sha:<pinned commit>"

[imports.bd]
source = "https://github.com/gastownhall/gascity.git//examples/bd"
version = "sha:<pinned commit>"

gc init also writes a matching packs.lock. The canonical pin is served offline from the binary's embedded copy; pinning a bundled source at any other commit makes it an ordinary remote import; gc import install fetches that exact commit from git, so editing the pin always does what it says.

The bd entry is written only for cities using the bd beads provider (the default); cities on other providers get only core. The bd pack pulls in the dolt pack transitively via its own [imports.dolt], so dolt never needs its own import. The gastown and gascity packs are also bundled but never required -- they arrive via the templates that use them (gc init gastown/gascity options) or an explicit import.

Core Pack

The bundled core pack contributes the baseline behavior that helps agents operate in a Gas City workspace:

The core pack deliberately ships no agents. Packs that need long-lived utility workers define their own -- for example, the gastown pack owns the dog utility pool and the mol-shutdown-dance formula, and the dolt pack ships its own separate dog agent for Dolt maintenance formulas.

Doctor Repair And Migration

gc doctor includes a fixable check named builtin-pack-imports. It flags required built-in imports missing from the composed config and legacy workspace.includes entries that point at the retired per-city .gc/system/packs tree, and gc doctor --fix migrates the city: it strips the legacy includes from city.toml, adds the missing pinned imports to pack.toml (creating a minimal one for legacy cities), and refreshes packs.lock plus the cache.

Config load re-seeds the user-global cache for canonically pinned bundled sources, prunes any leftover .gc/system/packs tree, and emits a once-per-city warning when a required built-in import is missing from the composed config. Bundled sources pinned at non-canonical commits are left to gc import install like any other remote import.

Inspect The Files

To inspect the exact core-pack files your city composes, resolve the import and look inside the cache:

$ gc import check
$ find "$(gc config show --json | jq -r '.pack_dirs[] | select(test("packs/core"))')" -maxdepth 2 -type f | sort

The cached files are implementation assets owned by gc. They are useful for learning and debugging, but local edits are not a stable customization surface (the binary restores its embedded content). Put custom behavior in your own city files or packs instead.

Related Commands

Some commands show the artifacts after the builtin packs are loaded:

gc pack registry ... commands discover public registry entries. They do not make the built-in core pack a registry dependency.