> ## Documentation Index > Fetch the complete documentation index at: https://docs.agentfacets.io/llms.txt > Use this file to discover all available pages before exploring further. # Build > Produce the canonical .facet archive `facet build` produces the canonical `.facet` archive from the author's source tree and writes it to `dist/-.facet`. This is the artifact of record: the bytes [`facet publish`](/specification/publish) will later verify and upload. There is a single source of truth for what a `.facet` is: the two-layer [archive format](/specification/archive), whose content-hash contract is described in the [Integrity Model](/specification/integrity). ## Steps 0. **Adapter compatibility preflight.** Every installed adapter MUST declare an adapter API the CLI supports. An installed adapter with a missing, malformed, or unsupported declaration MUST fail the build here — before manifest metadata validation and before any adapter method is invoked — with diagnostics identifying each incompatible adapter and its reinstall command. This gate applies to *installed* adapters; adapters that are named in the manifest but not installed are handled in step 4. 1. **Parse and validate the manifest.** Read the facet manifest (`facet.json`) and validate it against the [manifest schema](/specification/manifest). Invalid manifests MUST be rejected with a descriptive error. The manifest's `name` MUST be a valid facet identity; the `version` MUST be a semver string; at least one text asset MUST be declared. 2. **Resolve prompts.** Read each declared asset file from its conventional path: `skills//SKILL.md` for skills, `agents/.md` for agents, `commands/.md` for commands. Missing files are build errors. Primary asset files MUST NOT contain YAML front matter — the manifest is the single source of asset metadata, and a primary file that carries front matter is a build error. (Authoring tools strip front matter before writing.) 3. **Resolve supplementary files.** Read each declared [supplementary file](/specification/manifest#supplementary-files) as opaque bytes: top-level entries from the manifest's `files` array, and each skill's companions from its `files` array (relative to the skill directory). Supplementary bytes are shipped verbatim — binary and empty files are valid, and front matter is never parsed or stripped. A declared-but-missing file, a path that resolves to a symlink or non-regular file, an [unsafe or non-portable path](/specification/archive#content-rules), or a resolved-path collision is a build error. 4. **Validate content.** A declared primary asset MUST NOT be empty (zero bytes or whitespace only). Asset names MUST be single-segment [Agent Skills names](/specification/manifest#asset-names); skills and commands share one namespace and MUST NOT collide, while agents are separate. Compact `facets[]` entries MUST match the `name@version` shape. 5. **Validate adapter metadata.** For each asset with an `adapters` block, validate the adapter-specific metadata against each installed adapter's schema. Unknown adapters SHOULD produce a warning. Invalid metadata for an installed adapter MUST be a build error. 6. **Assemble the archive.** Drive collection and hashing from the shared archive plan derived from the manifest. Compute a per-entry SHA-256 hash for every entry — `facet.json`, primaries, and supplementary files alike. Assemble the deterministic inner tar. Compute the integrity hash over the uncompressed inner tar. Gzip the inner tar (`archive.tar.gz`). Assemble the outer tar containing `build-manifest.json` (recording the integrity hash and the complete `files` hash map) plus the gzipped inner archive. Write the result to `dist/-.facet`. The layout, determinism rules, and hash domains are specified in [Facet Archive](/specification/archive). Every build emits the current `facetVersion: 0.2` format — including asset-only facets, which carry no supplementary files. **Validation happens before cleanup:** all source inputs (steps 1–5) are validated before `dist/` is touched, so a build that fails validation leaves the previous `dist/` output intact. Only after validation succeeds does `facet build` purge `dist/` and write, so the directory contains exactly one `.facet` after a successful build: the archive for the current source's name and version. For a scoped facet identity, the name's `/` renders as a nested path under `dist/` — `@acme/cowsay` at `1.0.0` is written to `dist/@acme/cowsay-1.0.0.facet`, with parent directories created as required. Build output displays the emitted format version, the complete entry listing, and the integrity hash. ## Boundaries Building never contacts the registry and never mutates the manifest. What happens to the built artifact next — verification, upload, drift handling — is defined in [Publish](/specification/publish). Command usage and flags are documented at [`facet build`](/cli/authoring/build).