feat(playground): add shareable diff routes and refresh UI

README.md

@@ -15,6 +15,18 @@ endpoints, renders only MoonBit source/project files, and never accepts,
 stores, or sends a personal access token. Anonymous GitHub API rate limits
 therefore apply.
 
+Submitting a GitHub URL updates the browser to a static-host-friendly share
+route:
+
+```text
+https://{playground-host}/{base}/#/owner/repo/commit/sha
+```
+
+Opening that URL restores and loads the same commit automatically. The result
+page also exposes the full URL in a read-only field with a one-click copy
+button. Hash routing keeps shared links working on GitHub Pages without a
+server-side rewrite rule.
+
 Run the live development server from the Warren app directory:
 
 ```sh

playground/main/logic_wbtest.mbt

@@ -49,6 +49,45 @@ test "parse supported GitHub commit URL forms" {
   assert_eq(pr.sha, "0123456789abcdef")
 }
 
+///|
+test "shared playground routes round-trip to canonical GitHub commit URLs" {
+  let reference = CommitRef::{
+    owner: "moonbit-community",
+    repo: "ldiff",
+    sha: "aBcDeF1",
+  }
+  assert_eq(
+    playground_route(reference),
+    "#/moonbit-community/ldiff/commit/aBcDeF1",
+  )
+  assert_eq(
+    canonical_github_url(reference),
+    "https://github.com/moonbit-community/ldiff/commit/aBcDeF1",
+  )
+  guard reference_from_playground_url(
+      "https://example.github.io/ldiff/#/moonbit-community/ldiff/commit/aBcDeF1",
+    )
+    is Ok(Some(parsed)) else {
+    fail("expected the shared route to parse")
+  }
+  assert_true(parsed == reference)
+  assert_true(
+    reference_from_playground_url("https://example.com/ldiff/") is Ok(None),
+  )
+  assert_true(
+    reference_from_playground_url(
+      "https://example.com/ldiff/#/moonbit-community/ldiff/pull/1",
+    )
+    is Err(_),
+  )
+  assert_true(
+    reference_from_playground_url(
+      "https://example.com/ldiff/#/bad owner/ldiff/commit/abcdef1",
+    )
+    is Err(_),
+  )
+}
+
 ///|
 test "reject unsupported or malformed URLs" {
   for
@@ -132,7 +171,7 @@ test "pagination appends file metadata and stops at GitHub's 30-page cap" {
   assert_false(should_fetch_next_page(1, 99))
   assert_false(should_fetch_next_page(30, 100))
   assert_true(
-    commit_api_url(CommitRef::{ owner: "a", repo: "b", sha: "abcdef1" }, 30).has_suffix(
+    commit_api_url({ owner: "a", repo: "b", sha: "abcdef1" }, 30).has_suffix(
       "?per_page=100&page=30",
     ),
   )
@@ -197,11 +236,14 @@ test "stale commit responses are discarded by generation" {
     generation: 2,
     view_mode: Split,
     phase: Idle,
+    route: None,
+    share_url: None,
+    copy_status: CopyReady,
   }
   let fixture = decode_commit(
     read_fixture("playground/main/fixtures/root_commit.json"),
   )
-  let emit : @rabbita.Emit[Msg] = @cmd.Emit(_ => @rabbita.none)
+  let emit : @rabbita.Emit[Msg] = Emit(_ => @rabbita.none)
   let (after, _) = update(model, CommitPageLoaded(1, 1, Ok(fixture)), emit)
   assert_true(after == model)
 }
@@ -215,7 +257,7 @@ test "only the first twenty matching files auto-load and stale source replies ar
   for index in 0..<21 {
     files.push(fixture_file("src/file_\{index}.mbt", "added"))
   }
-  let emit : @rabbita.Emit[Msg] = @cmd.Emit(_ => @rabbita.none)
+  let emit : @rabbita.Emit[Msg] = Emit(_ => @rabbita.none)
   let reference = CommitRef::{
     owner: "example",
     repo: "root",
@@ -235,6 +277,9 @@ test "only the first twenty matching files auto-load and stale source replies ar
     generation: 7,
     view_mode: Split,
     phase: Showing(view),
+    route: Some(reference),
+    share_url: None,
+    copy_status: CopyReady,
   }
   let (after, _) = update(model, SourceLoaded(6, 0, New, Ok("stale")), emit)
   assert_true(after == model)

playground/main/main.mbt

@@ -8,5 +8,12 @@
 
 ///|
 fn main {
-  @rabbita.elmish(model=initial_model(), view=app_view, update~).mount("app")
+  @rabbita.new(() => {
+    let (model, emit) = @rabbita.create_state_with_init(
+      init=app_init,
+      update~,
+      subscriptions=app_subscriptions,
+    )
+    model.map(model => app_view(model, emit))
+  }).mount("app")
 }

playground/main/moon.pkg

@@ -1,8 +1,11 @@
 import {
   "moonbit-community/ldiff",
   "moonbit-community/rabbita",
+  "moonbit-community/rabbita/clipboard",
   "moonbit-community/rabbita/html",
   "moonbit-community/rabbita/http",
+  "moonbit-community/rabbita/nav",
+  "moonbit-community/rabbita/sub",
   "moonbit-community/rabbita/url",
   "moonbitlang/core/encoding/utf8",
   "moonbitlang/core/json",

playground/main/share_url.mbt

@@ -0,0 +1,58 @@
+// Copyright 2026 International Digital Economy Academy
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+
+///|
+fn canonical_github_url(reference : CommitRef) -> String {
+  "https://github.com/\{reference.owner}/\{reference.repo}/commit/\{reference.sha}"
+}
+
+///|
+fn playground_route(reference : CommitRef) -> String {
+  "#/\{reference.owner}/\{reference.repo}/commit/\{reference.sha}"
+}
+
+///|
+fn reference_from_route(fragment : String?) -> Result[CommitRef?, String] {
+  guard fragment is Some(value) && !value.is_empty() else { return Ok(None) }
+  let parts : Array[String] = value
+    .split("/")
+    .map(StringView::to_owned)
+    .collect()
+  let reference = match parts {
+    ["", owner, repo, "commit", sha] | [owner, repo, "commit", sha] =>
+      CommitRef::{ owner, repo, sha }
+    _ => return Err("This shared playground link is not valid.")
+  }
+  if !valid_owner(reference.owner) ||
+    !valid_repo(reference.repo) ||
+    !valid_sha(reference.sha) {
+    return Err("This shared playground link is not valid.")
+  }
+  Ok(Some(reference))
+}
+
+///|
+fn reference_from_playground_url(input : String) -> Result[CommitRef?, String] {
+  let parsed = try @url.parse(input) catch {
+    _ => return Err("This shared playground link is not valid.")
+  } noraise {
+    parsed => parsed
+  }
+  reference_from_route(parsed.fragment)
+}
+
+///|
+extern "js" fn browser_current_url() -> String = "() => window.location.href"
+
+///|
+extern "js" fn browser_base_url() -> String = "() => window.location.origin + window.location.pathname"
+
+///|
+fn playground_share_url(reference : CommitRef) -> String {
+  "\{browser_base_url()}\{playground_route(reference)}"
+}