Name each database target's archive for its webhook and target (closes #376)

Each database target now has its own archive file,
archive-WEBHOOKNAME-TARGETNAME-TARGETID.db, instead of one
archive-WEBHOOKID.db per webhook. delivery.ArchiveFileName builds the
name: each name is lowercased, keeps ASCII letters and digits, turns
every other run of characters into one dash, and is cut to 40
characters.

A change of webhook or target name renames its archive files under the
archive writer's lock, before the new name is saved, and back again if
the save fails. A rename never replaces a file: if one already has the
new name, the edit is refused. Deleting a target evicts only that
target's writer. Archive files are never deleted, and nothing looks for
files under the old name.

Model: opus-5-5

internal/handlers/target_edit_test.go

@@ -635,3 +635,68 @@ func assertWebhookOfAnotherUser404s(
 
 	assert.Equal(t, http.StatusNotFound, w.Code)
 }
+
+// renamedTargetName is the name the rename tests give a target.
+const renamedTargetName = "Long Term"
+
+// TestHandleTargetEditSubmit_RenamesArchive proves that renaming a
+// database target renames its archive, that a save that keeps the
+// name renames nothing, that a target of another type has no archive
+// to rename, and that a target whose archive cannot be renamed keeps
+// its stored name. When a file already has the archive's new name,
+// the edit is refused with an error naming that file.
+func TestHandleTargetEditSubmit_RenamesArchive(t *testing.T) {
+	t.Parallel()
+
+	env := setupSourceTest(t)
+	wh := seedWebhookWithRetention(t, env.db, 7)
+	archive := seedTarget(t, env.db, wh.ID, database.TargetTypeDatabase)
+	rename := url.Values{"name": {renamedTargetName}}
+
+	w := submitTargetEdit(env, wh.ID, archive.ID, rename)
+	require.Equal(t, http.StatusSeeOther, w.Code, w.Body.String())
+	assert.Equal(
+		t,
+		[]archiveRename{{archive.ID, wh.Name, renamedTargetName}},
+		env.archives.Renames(),
+	)
+
+	w = submitTargetEdit(env, wh.ID, archive.ID, rename)
+	require.Equal(t, http.StatusSeeOther, w.Code, w.Body.String())
+	assert.Len(
+		t, env.archives.Renames(), 1,
+		"a save that keeps the name renames nothing",
+	)
+
+	httpWebhook, httpTarget := seedHTTPTarget(t, env, "", "")
+
+	w = submitTargetEdit(
+		env, httpWebhook.ID, httpTarget.ID,
+		editForm(editOriginalURL, "", ""),
+	)
+	require.Equal(t, http.StatusSeeOther, w.Code, w.Body.String())
+	assert.Len(
+		t, env.archives.Renames(), 1,
+		"an HTTP target has no archive to rename",
+	)
+
+	again := url.Values{"name": {"Again"}}
+
+	env.archives.FailRenames(errInjectedRename)
+
+	w = submitTargetEdit(env, wh.ID, archive.ID, again)
+	require.Equal(t, http.StatusInternalServerError, w.Code)
+	assert.Equal(
+		t, renamedTargetName, storedTarget(t, env, archive.ID).Name,
+		"a target whose archive was not renamed keeps its name",
+	)
+
+	env.archives.FailRenames(errNameTaken)
+
+	w = submitTargetEdit(env, wh.ID, archive.ID, again)
+	require.Equal(t, http.StatusConflict, w.Code)
+	assert.Contains(t, w.Body.String(), "archive-taken.db")
+	assert.Equal(
+		t, renamedTargetName, storedTarget(t, env, archive.ID).Name,
+	)
+}