feat(parser): add reusable source-set bases and functional options

Introduce the SourceSet bases (JSONL, directory JSONL, single-file,
multi-session container, sibling-metadata, SQLite fan-out), the
functional with*() option set, the generic SourceSet provider/factory
plumbing, and the virtual-path and source-identity helpers up front, so
every provider migration constructs its source set through options
instead of a struct literal.

Author: mariusvniekerk

internal/parser/directory_jsonl_source_set.go

@@ -0,0 +1,59 @@
+package parser
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+// DirectoryJSONLSourceSet constrains JSONL sources to the common
+// <root>/<project>/<session>.<ext> shape while keeping JSONLSourceSet's source
+// methods available through embedding.
+type DirectoryJSONLSourceSet struct {
+	JSONLSourceSet
+}
+
+// newDirectoryJSONLSourceSet returns a JSONL source helper for providers whose
+// transcripts live one project directory below each configured root. The
+// returned helper is always recursive enough to classify watched project files,
+// but it rejects root-level and deeper nested files through IncludePath.
+func newDirectoryJSONLSourceSet(
+	provider AgentType,
+	roots []string,
+	opts ...jsonlOption,
+) DirectoryJSONLSourceSet {
+	var options JSONLSourceSetOptions
+	for _, opt := range opts {
+		opt(&options)
+	}
+	userIncludePath := options.IncludePath
+	options.Recursive = true
+	options.IncludePath = func(root, path string) bool {
+		if !isDirectoryJSONLPath(root, path) {
+			return false
+		}
+		return userIncludePath == nil || userIncludePath(root, path)
+	}
+	if options.ProjectHint == nil {
+		options.ProjectHint = func(root, path string) string {
+			return directoryJSONLProjectFromPath(path)
+		}
+	}
+	return DirectoryJSONLSourceSet{
+		JSONLSourceSet: jsonlSourceSetFromOptions(provider, roots, options),
+	}
+}
+
+func isDirectoryJSONLPath(root, path string) bool {
+	rel, err := filepath.Rel(root, path)
+	if err != nil {
+		return false
+	}
+	parts := strings.Split(rel, string(filepath.Separator))
+	return len(parts) == 2 &&
+		parts[0] != "" && parts[0] != "." && parts[0] != ".." &&
+		parts[1] != "" && parts[1] != "." && parts[1] != ".."
+}
+
+func directoryJSONLProjectFromPath(path string) string {
+	return filepath.Base(filepath.Dir(path))
+}

internal/parser/file_identity_unix.go

@@ -0,0 +1,15 @@
+//go:build unix
+
+package parser
+
+import (
+	"os"
+	"syscall"
+)
+
+func sourceFileIdentity(info os.FileInfo) (inode, device uint64) {
+	if stat, ok := info.Sys().(*syscall.Stat_t); ok {
+		return uint64(stat.Ino), uint64(stat.Dev)
+	}
+	return 0, 0
+}

internal/parser/file_identity_windows.go

@@ -0,0 +1,9 @@
+//go:build windows
+
+package parser
+
+import "os"
+
+func sourceFileIdentity(info os.FileInfo) (inode, device uint64) {
+	return 0, 0
+}