diff --git a/README.md b/README.md
index fce99ec..8ab90c8 100644
--- a/README.md
+++ b/README.md
@@ -90,7 +90,7 @@ To build locally instead: `docker build -t asterism .`
 
 ## API
 
-Asterism implements all five current endpoints from the [microcosm links XRPC namespace](https://constellation.microcosm.blue/) (the older `/links/*` REST endpoints are deprecated upstream in favor of these and aren't implemented here):
+Asterism implements all five current endpoints from the [microcosm links XRPC namespace](https://constellation.microcosm.blue/) (the older `/links/*` REST endpoints are deprecated upstream in favor of these and aren't implemented here), plus one identity endpoint borrowed from [Slingshot](https://slingshot.microcosm.blue/):
 
 ### `GET /xrpc/blue.microcosm.links.getBacklinksCount`
 
@@ -168,6 +168,16 @@ Response: `{"counts_by_other_subject": [{"subject": "...", "total": 42, "distinc
 
 Note the DID filter parameter is `did` here, not `linkDid` like `getManyToMany` — a real inconsistency in the upstream Constellation API (their own source flags it as a known TODO), preserved here for compatibility rather than "fixed."
 
+### `GET /xrpc/blue.microcosm.identity.resolveMiniDoc`
+
+Resolve a handle or DID to its identity. Asterism already resolves DIDs to verify commit signatures against the repo's signing key, so this endpoint is essentially free.
+
+| Parameter    | Description                          |
+| ------------ | ------------------------------------- |
+| `identifier` | Handle or DID to resolve (required)  |
+
+Response: `{"did": "...", "handle": "...", "pds": "...", "signing_key": "..."}`
+
 ## Roadmap
 
 **Near term**
diff --git a/cmd/asterism/main.go b/cmd/asterism/main.go
index ff8bc1f..377c22e 100644
--- a/cmd/asterism/main.go
+++ b/cmd/asterism/main.go
@@ -68,7 +68,9 @@ func main() {
 		panic(err)
 	}
 
-	server := &api.Server{Store: linkStore}
+	directory := identity.DefaultDirectory()
+
+	server := &api.Server{Store: linkStore, Directory: directory}
 	go func() {
 		if err := server.Run(cli.Listen); err != nil {
 			panic(err)
@@ -86,7 +88,7 @@ func main() {
 
 	bf := &backfill.Backfill{
 		Client:    &xrpc.Client{Host: relayHTTPHost(cli.Relay)},
-		Directory: identity.DefaultDirectory(),
+		Directory: directory,
 		Store:     linkStore,
 	}
 
@@ -103,7 +105,7 @@ func main() {
 	consumer := &firehose.Consumer{
 		WantedCollections: wantedCollections,
 		Store:             linkStore,
-		Directory:         bf.Directory,
+		Directory:         directory,
 		Backfill:          bf,
 	}
 
diff --git a/internal/api/resolve_mini_doc.go b/internal/api/resolve_mini_doc.go
new file mode 100644
index 0000000..f32aaff
--- /dev/null
+++ b/internal/api/resolve_mini_doc.go
@@ -0,0 +1,57 @@
+package api
+
+import (
+	"context"
+	"encoding/json"
+	"log"
+	"net/http"
+	"time"
+
+	"github.com/bluesky-social/indigo/atproto/syntax"
+)
+
+type getMiniDidDocResponse struct {
+	Did        string `json:"did"`
+	Handle     string `json:"handle"`
+	Pds        string `json:"pds"`
+	SigningKey string `json:"signing_key"`
+}
+
+func (s *Server) GetMiniDidDoc(w http.ResponseWriter, r *http.Request) {
+	query := r.URL.Query()
+
+	identifier := query.Get("identifier")
+	if identifier == "" {
+		http.Error(w, "identifier is required", http.StatusBadRequest)
+		return
+	}
+
+	atID, err := syntax.ParseAtIdentifier(identifier)
+	if err != nil {
+		http.Error(w, "invalid identifier", http.StatusBadRequest)
+		return
+	}
+
+	resolveCtx, cancel := context.WithTimeout(r.Context(), 10*time.Second)
+	defer cancel()
+
+	identity, err := s.Directory.Lookup(resolveCtx, atID)
+	if err != nil {
+		log.Println("resolve mini doc:", err)
+		http.Error(w, "internal error", http.StatusInternalServerError)
+		return
+	}
+
+	var signingKey string
+	if key, ok := identity.Keys["atproto"]; ok {
+		signingKey = key.PublicKeyMultibase
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(getMiniDidDocResponse{
+		Did:        identity.DID.String(),
+		Handle:     identity.Handle.String(),
+		Pds:        identity.PDSEndpoint(),
+		SigningKey: signingKey,
+	})
+}
diff --git a/internal/api/server.go b/internal/api/server.go
index 4b35eb8..955f9b0 100644
--- a/internal/api/server.go
+++ b/internal/api/server.go
@@ -4,10 +4,12 @@ import (
 	"net/http"
 
 	"github.com/alyraffauf/asterism/internal/store"
+	"github.com/bluesky-social/indigo/atproto/identity"
 )
 
 type Server struct {
-	Store *store.Store
+	Store     *store.Store
+	Directory identity.Directory
 }
 
 func (s *Server) Run(addr string) error {
@@ -20,6 +22,8 @@ func (s *Server) Run(addr string) error {
 	mux.HandleFunc("GET /xrpc/blue.microcosm.links.getManyToMany", s.GetManyToMany)
 	mux.HandleFunc("GET /xrpc/blue.microcosm.links.getManyToManyCounts", s.GetManyToManyCounts)
 
+	mux.HandleFunc("GET /xrpc/blue.microcosm.identity.resolveMiniDoc", s.GetMiniDidDoc)
+
 	return http.ListenAndServe(addr, withCORS(mux))
 }