@@ -49,6 +49,12 @@ knot text not null,
 			created text not null default (strftime('%Y-%m-%dT%H:%M:%SZ', 'now')),
 			unique(did, name, knot)
 		);
+		create table if not exists collaborators (
+			id integer primary key autoincrement,
+			did text not null,
+			repo integer not null,
+			foreign key (repo) references repos(id) on delete cascade
+		);
 		create table if not exists follows (
 			user_did text not null,
 			subject_did text not null,

@@ -1,6 +1,9 @@
 package db
 
-import "time"
+import (
+	"database/sql"
+	"time"
+)
 
 type Repo struct {
 	Did     string
@@ -19,14 +22,11 @@ }
 	defer rows.Close()
 
 	for rows.Next() {
-		var repo Repo
-		var createdAt string
-		if err := rows.Scan(&repo.Did, &repo.Name, &repo.Knot, &createdAt); err != nil {
+		repo, err := scanRepo(rows)
+		if err != nil {
 			return nil, err
 		}
-		createdAtTime, _ := time.Parse(time.RFC3339, createdAt)
-		repo.Created = &createdAtTime
-		repos = append(repos, repo)
+		repos = append(repos, *repo)
 	}
 
 	if err := rows.Err(); err != nil {
@@ -60,3 +60,53 @@ func (d *DB) RemoveRepo(did, name, knot string) error {
 	_, err := d.db.Exec(`delete from repos where did = ? and name = ? and knot = ?`, did, name, knot)
 	return err
 }
+
+func (d *DB) AddCollaborator(collaborator, repoOwnerDid, repoName, repoKnot string) error {
+	_, err := d.db.Exec(
+		`insert into collaborators (did, repo)
+		values (?, (select id from repos where did = ? and name = ? and knot = ?));`,
+		collaborator, repoOwnerDid, repoName, repoKnot)
+	return err
+}
+
+func (d *DB) CollaboratingIn(collaborator string) ([]Repo, error) {
+	var repos []Repo
+
+	rows, err := d.db.Query(`select r.* from repos r join collaborators c on r.id = c.repo where c.did = ?;`, collaborator)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	for rows.Next() {
+		repo, err := scanRepo(rows)
+		if err != nil {
+			return nil, err
+		}
+		repos = append(repos, *repo)
+	}
+
+	if err := rows.Err(); err != nil {
+		return nil, err
+	}
+
+	return repos, nil
+}
+
+func scanRepo(rows *sql.Rows) (*Repo, error) {
+	var repo Repo
+	var createdAt string
+	if err := rows.Scan(&repo.Did, &repo.Name, &repo.Knot, &createdAt); err != nil {
+		return nil, err
+	}
+
+	createdAtTime, err := time.Parse(time.RFC3339, createdAt)
+	if err != nil {
+		now := time.Now()
+		repo.Created = &now
+	}
+
+	repo.Created = &createdAtTime
+
+	return &repo, nil
+}

@@ -29,6 +29,9 @@ return template.FuncMap{
 		"split": func(s string) []string {
 			return strings.Split(s, "\n")
 		},
+		"splitOn": func(s, sep string) []string {
+			return strings.Split(s, sep)
+		},
 		"add": func(a, b int) int {
 			return a + b
 		},
@@ -89,6 +92,9 @@ paragraphs[i] = strings.Join(lines, " ")
 			}
 
 			return strings.Join(paragraphs, "\n\n")
+		},
+		"sequence": func(n int) []struct{} {
+			return make([]struct{}, n)
 		},
 	}
 }
@@ -200,10 +206,11 @@ return p.execute("repo/new", w, params)
 }
 
 type ProfilePageParams struct {
-	LoggedInUser *auth.User
-	UserDid      string
-	UserHandle   string
-	Repos        []db.Repo
+	LoggedInUser       *auth.User
+	UserDid            string
+	UserHandle         string
+	Repos              []db.Repo
+	CollaboratingRepos []db.Repo
 }
 
 func (p *Pages) ProfilePage(w io.Writer, params ProfilePageParams) error {

@@ -102,18 +102,19 @@ <p>Not showing binary file.</p>
           {{ else }}
             <pre class="overflow-auto">
             {{- range .TextFragments -}}
-              <div class="bg-gray-100 text-gray-500">{{ nl2br .Header }}</div>
+              <div class="bg-gray-100 text-gray-500 select-none">{{ .Comment }}</div>
+
               {{- range .Lines -}}
                   {{- if eq .Op.String "+" -}}
-                  <div class="bg-green-100 text-green-700">{{ .String }}</div>
+                  <div class="bg-green-100 text-green-700"><span class="select-none">{{ .Op.String }}</span><span>{{ .Line }}</span></div>
                   {{- end -}}
 
                   {{- if eq .Op.String "-" -}}
-                  <div class="bg-red-100 text-red-700">{{ .String }}</div>
+                  <div class="bg-red-100 text-red-700"><span class="select-none">{{ .Op.String }}</span><span>{{ .Line }}</span></div>
                   {{- end -}}
 
                   {{- if eq .Op.String " " -}}
-                  <div class="text-gray-500">{{ .String }}</div>
+                  <div class="text-gray-500"><span class="select-none">{{ .Op.String }}</span><span>{{ .Line }}</span></div>
                   {{- end -}}
 
               {{- end -}}

@@ -2,7 +2,8 @@ {{ define "title" }}{{ or .UserHandle .UserDid }}{{ end }}
 
 {{ define "content" }}
     <h1>{{ didOrHandle .UserDid .UserHandle }}</h1>
-    <div id="my-repos" class="grid grid-cols-1 md:grid-cols-2 gap-4">
+    <p class="text-xs font-bold py-2">REPOS</p>
+    <div id="repos" class="grid grid-cols-1 md:grid-cols-2 gap-4 mb-6">
         {{ range .Repos }}
             <div
                 id="repo-card"
@@ -22,6 +23,29 @@ </div>
             </div>
         {{ else }}
             <p>This user does not have any repos yet.</p>
+        {{ end }}
+    </div>
+    <p class="text-xs font-bold py-2">COLLABORATING ON</p>
+    <div id="collaborating" class="grid grid-cols-1 md:grid-cols-2 gap-4 mb-6">
+        {{ range .CollaboratingRepos }}
+            <div
+                id="repo-card"
+                class="border border-black p-4 shadow-sm bg-white"
+            >
+                <div id="repo-card-name" class="font-medium">
+                    <a href="/@{{ or $.UserHandle $.UserDid }}/{{ .Name }}">
+                      @{{ or $.UserHandle $.UserDid }}/{{ .Name }}
+                    </a>
+                </div>
+                <div
+                    id="repo-knot-name"
+                    class="text-gray-600 text-sm font-mono"
+                >
+                    {{ .Knot }}
+                </div>
+            </div>
+        {{ else }}
+            <p>This user is not collaborating.</p>
         {{ end }}
     </div>
 {{ end }}

@@ -393,6 +393,12 @@ w.Write([]byte(fmt.Sprint("failed to add collaborator: ", err)))
 		return
 	}
 
+	err = s.db.AddCollaborator(collaboratorIdent.DID.String(), f.OwnerDid(), f.RepoName, f.Knot)
+	if err != nil {
+		w.Write([]byte(fmt.Sprint("failed to add collaborator: ", err)))
+		return
+	}
+
 	w.Write([]byte(fmt.Sprint("added collaborator: ", collaboratorIdent.Handle.String())))
 
 }

@@ -580,11 +580,17 @@ if err != nil {
 		log.Printf("getting repos for %s: %s", ident.DID.String(), err)
 	}
 
+	collaboratingRepos, err := s.db.CollaboratingIn(ident.DID.String())
+	if err != nil {
+		log.Printf("getting collaborating repos for %s: %s", ident.DID.String(), err)
+	}
+
 	s.pages.ProfilePage(w, pages.ProfilePageParams{
-		LoggedInUser: s.auth.GetUser(r),
-		UserDid:      ident.DID.String(),
-		UserHandle:   ident.Handle.String(),
-		Repos:        repos,
+		LoggedInUser:       s.auth.GetUser(r),
+		UserDid:            ident.DID.String(),
+		UserHandle:         ident.Handle.String(),
+		Repos:              repos,
+		CollaboratingRepos: collaboratingRepos,
 	})
 }
 

@@ -66,8 +66,8 @@ ndiff.IsDelete = d.IsDelete
 
 		for _, tf := range d.TextFragments {
 			ndiff.TextFragments = append(ndiff.TextFragments, types.TextFragment{
-				Header: tf.Header(),
-				Lines:  tf.Lines,
+				Comment: tf.Comment,
+				Lines:   tf.Lines,
 			})
 			for _, l := range tf.Lines {
 				switch l.Op {

@@ -6,8 +6,8 @@ "github.com/go-git/go-git/v5/plumbing/object"
 )
 
 type TextFragment struct {
-	Header string         `json:"header"`
-	Lines  []gitdiff.Line `json:"lines"`
+	Comment string         `json:"comment"`
+	Lines   []gitdiff.Line `json:"lines"`
 }
 
 type Diff struct {