Update documentation relating to the public packages and http_upload API

docs/consumers/pkg-bundle.md

@@ -0,0 +1,88 @@
+# `pkg/bundle`
+
+Audience: upstream Go producer developers and LLM coding agents using `distributor` source bundle helpers.
+
+Import path:
+
+```go
+import "gitea.maximumdirect.net/eric/distributor/pkg/bundle"
+```
+
+`pkg/bundle` builds, writes, parses, and validates local source bundles. Use it directly when a producer writes bundles for `distributor` to discover, or when a producer wants to assemble and validate a bundle before using another transport.
+
+The canonical source bundle file-format contract is [Source Bundle Contract](../integrations/source-bundle.md).
+
+## Preferred Complete-Bundle Workflow
+
+Use `WriteBundle` when producer-generated files live outside the final bundle root.
+
+```go
+manifest, err := bundle.WriteBundle(bundle.WriteBundleOptions{
+	Root: "/var/spool/distributor/weather/hourly-2026-06-07T15",
+	ID:   "weather.hourly.brentwood.2026-06-07T15",
+	Files: []bundle.BundleFile{
+		{SourcePath: "/tmp/weather/report.md", Path: "report.md"},
+		{SourcePath: "/tmp/weather/summary.txt", Path: "summary.txt"},
+	},
+})
+if err != nil {
+	return err
+}
+_ = manifest
+```
+
+`WriteBundle` copies each source file into a staged bundle root, writes `manifest.json`, validates the staged bundle, and promotes it into place. Set `Overwrite: true` only when the producer intentionally replaces an existing bundle root.
+
+## Existing Bundle Root Workflow
+
+Use `BuildManifest` and `WriteManifest` when files are already staged under the final bundle root.
+
+```go
+root := "/var/spool/distributor/weather/hourly-2026-06-07T15"
+manifest, err := bundle.BuildManifest(bundle.BuildOptions{
+	Root:  root,
+	ID:    "weather.hourly.brentwood.2026-06-07T15",
+	Files: []string{"report.md", "summary.txt"},
+})
+if err != nil {
+	return err
+}
+if err := bundle.WriteManifest(root, manifest, bundle.WriteManifestOptions{}); err != nil {
+	return err
+}
+if err := bundle.ValidateBundle(root, manifest); err != nil {
+	return err
+}
+```
+
+Use `Scan: true` instead of `Files` only when every valid regular file under the root should be included. Scan mode includes dotfiles, skips reserved metadata files, rejects symlinks, and sorts paths lexically.
+
+## Paths And Ordering
+
+Bundle paths are slash-separated paths relative to the bundle root.
+
+Invalid paths include:
+
+- empty paths;
+- absolute paths;
+- paths containing backslashes;
+- `.` or `..` path segments;
+- empty path segments;
+- any basename of `manifest.json` or `.distributor.json`.
+
+Explicit file lists preserve caller order. File order is part of the bundle digest, so producers should choose it deliberately and keep it stable.
+
+## Validation And Digest Helpers
+
+Use `ValidateBundle` before handing an existing local bundle to another process. It verifies manifest semantics, file existence, regular-file type, file size, per-file SHA-256 digests, and bundle digest.
+
+Useful helpers:
+
+- `LoadManifest`: read `manifest.json` from a bundle root.
+- `ParseManifest` and `MarshalManifest`: parse or write manifest bytes.
+- `ValidateManifest`: validate manifest-only semantics.
+- `FileDigest`, `BundleDigest`, and `ValidateDigest`: digest helpers for diagnostics and tests.
+
+## Boundaries
+
+`pkg/bundle` does not upload bundles, publish destinations, transform Markdown, select pipelines, configure credentials, or write destination state. Those concerns belong to `pkg/upload` or the `distributor` application.