Rename "channels" to "conversations."

The term "channel" for a conversational container has a long and storied history, but is mostly evocative of IRC and of other, ah, "nerd-centric" services. It does show up in more widespread contexts: Discord and Slack both refer to their primary conversational containers as "channels," for example. However, I think it's unnecessary jargon, and I'd like to do away with it.

To that end, this change pervasively changes one term to the other wherever it appears, with the following exceptions:

* A `channel` concept (unrelated to conversations) is also provided by an external library; we can't and shouldn't try to rename that.
* The code to deal with the `pilcrow:channelData` and `pilcrow:lastActiveChannel` local storage properties is still present, to migrate existing data to new keys. It will be removed in a later change.

This is a **breaking API change**. As we are not yet managing any API compatibility promises, this is formally not an issue, but it is something to be aware of practically. The major API changes are:

* Paths beginning with `/api/channels` are now under `/api/conversations`, without other modifications.
* Fields labelled with `channel…` terms are now labelled with `conversation…` terms. For example, a `message` `sent` event is now sent to a `conversation`, not a `channel`.

This is also a **breaking UI change**. Specifically, any saved paths for `/ch/CHANNELID` will now lead to a 404. The corresponding paths are `/c/CONVERSATIONID`. While I've made an effort to migrate the location of stored data, I have not tried to provide adapters to fix this specific issue, because the disruption is short-lived and very easily addressed by opening a channel in the client UI.

This change is obnoxiously large and difficult to review, for which I apologize. If this shows up in `git annotate`, please forgive me. These kinds of renamings are hard to carry out without a major disruption, especially when the concept ("channel" in this case) is used so pervasively throughout the system.

I think it's worth making this change that pervasively so that we don't have an indefinitely-long tail of "well, it's a conversation in the docs, but the table is called `channel` for historical reasons" type issues.

Merges conversations-not-channels into main.

1 files changed, 273 insertions, 0 deletions

diff --git a/src/event/handlers/stream/test/conversation.rs b/src/event/handlers/stream/test/conversation.rs
new file mode 100644
index 0000000..5e08075
--- /dev/null
+++ b/src/event/handlers/stream/test/conversation.rs
@@ -0,0 +1,273 @@
+use axum::extract::State;
+use axum_extra::extract::Query;
+use futures::{future, stream::StreamExt as _};
+
+use crate::test::fixtures::{self, future::Expect as _};
+
+#[tokio::test]
+async fn creating() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let resume_point = fixtures::boot::resume_point(&app).await;
+
+    // Subscribe
+
+    let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Response(events) = super::handler(
+        State(app.clone()),
+        subscriber,
+        None,
+        Query(super::QueryParams { resume_point }),
+    )
+    .await
+    .expect("subscribe never fails");
+
+    // Create a conversation
+
+    let name = fixtures::conversation::propose();
+    let conversation = app
+        .conversations()
+        .create(&name, &fixtures::now())
+        .await
+        .expect("creating a conversation succeeds");
+
+    // Verify conversation created event
+
+    events
+        .filter_map(fixtures::event::stream::conversation)
+        .filter_map(fixtures::event::stream::conversation::created)
+        .filter(|event| future::ready(event.conversation == conversation))
+        .next()
+        .expect_some("conversation created event is delivered")
+        .await;
+}
+
+#[tokio::test]
+async fn previously_created() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let resume_point = fixtures::boot::resume_point(&app).await;
+
+    // Create a conversation
+
+    let name = fixtures::conversation::propose();
+    let conversation = app
+        .conversations()
+        .create(&name, &fixtures::now())
+        .await
+        .expect("creating a conversation succeeds");
+
+    // Subscribe
+
+    let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Response(events) = super::handler(
+        State(app.clone()),
+        subscriber,
+        None,
+        Query(super::QueryParams { resume_point }),
+    )
+    .await
+    .expect("subscribe never fails");
+
+    // Verify conversation created event
+
+    let _ = events
+        .filter_map(fixtures::event::stream::conversation)
+        .filter_map(fixtures::event::stream::conversation::created)
+        .filter(|event| future::ready(event.conversation == conversation))
+        .next()
+        .expect_some("conversation created event is delivered")
+        .await;
+}
+
+#[tokio::test]
+async fn expiring() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let conversation = fixtures::conversation::create(&app, &fixtures::ancient()).await;
+    let resume_point = fixtures::boot::resume_point(&app).await;
+
+    // Subscribe
+
+    let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Response(events) = super::handler(
+        State(app.clone()),
+        subscriber,
+        None,
+        Query(super::QueryParams { resume_point }),
+    )
+    .await
+    .expect("subscribe never fails");
+
+    // Expire conversations
+
+    app.conversations()
+        .expire(&fixtures::now())
+        .await
+        .expect("expiring conversations always succeeds");
+
+    // Check for expiry event
+    let _ = events
+        .filter_map(fixtures::event::stream::conversation)
+        .filter_map(fixtures::event::stream::conversation::deleted)
+        .filter(|event| future::ready(event.id == conversation.id))
+        .next()
+        .expect_some("a deleted conversation event will be delivered")
+        .await;
+}
+
+#[tokio::test]
+async fn previously_expired() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let conversation = fixtures::conversation::create(&app, &fixtures::ancient()).await;
+    let resume_point = fixtures::boot::resume_point(&app).await;
+
+    // Expire conversations
+
+    app.conversations()
+        .expire(&fixtures::now())
+        .await
+        .expect("expiring conversation always succeeds");
+
+    // Subscribe
+
+    let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Response(events) = super::handler(
+        State(app.clone()),
+        subscriber,
+        None,
+        Query(super::QueryParams { resume_point }),
+    )
+    .await
+    .expect("subscribe never fails");
+
+    // Check for expiry event
+    let _ = events
+        .filter_map(fixtures::event::stream::conversation)
+        .filter_map(fixtures::event::stream::conversation::deleted)
+        .filter(|event| future::ready(event.id == conversation.id))
+        .next()
+        .expect_some("a deleted conversation event will be delivered")
+        .await;
+}
+
+#[tokio::test]
+async fn deleting() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let conversation = fixtures::conversation::create(&app, &fixtures::now()).await;
+    let resume_point = fixtures::boot::resume_point(&app).await;
+
+    // Subscribe
+
+    let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Response(events) = super::handler(
+        State(app.clone()),
+        subscriber,
+        None,
+        Query(super::QueryParams { resume_point }),
+    )
+    .await
+    .expect("subscribe never fails");
+
+    // Delete the conversation
+
+    app.conversations()
+        .delete(&conversation.id, &fixtures::now())
+        .await
+        .expect("deleting a valid conversation succeeds");
+
+    // Check for delete event
+    let _ = events
+        .filter_map(fixtures::event::stream::conversation)
+        .filter_map(fixtures::event::stream::conversation::deleted)
+        .filter(|event| future::ready(event.id == conversation.id))
+        .next()
+        .expect_some("a deleted conversation event will be delivered")
+        .await;
+}
+
+#[tokio::test]
+async fn previously_deleted() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let conversation = fixtures::conversation::create(&app, &fixtures::now()).await;
+    let resume_point = fixtures::boot::resume_point(&app).await;
+
+    // Delete the conversation
+
+    app.conversations()
+        .delete(&conversation.id, &fixtures::now())
+        .await
+        .expect("deleting a valid conversation succeeds");
+
+    // Subscribe
+
+    let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Response(events) = super::handler(
+        State(app.clone()),
+        subscriber,
+        None,
+        Query(super::QueryParams { resume_point }),
+    )
+    .await
+    .expect("subscribe never fails");
+
+    // Check for expiry event
+    let _ = events
+        .filter_map(fixtures::event::stream::conversation)
+        .filter_map(fixtures::event::stream::conversation::deleted)
+        .filter(|event| future::ready(event.id == conversation.id))
+        .next()
+        .expect_some("a deleted conversation event will be delivered")
+        .await;
+}
+
+#[tokio::test]
+async fn previously_purged() {
+    // Set up the environment
+
+    let app = fixtures::scratch_app().await;
+    let conversation = fixtures::conversation::create(&app, &fixtures::ancient()).await;
+    let resume_point = fixtures::boot::resume_point(&app).await;
+
+    // Delete and purge the conversation
+
+    app.conversations()
+        .delete(&conversation.id, &fixtures::ancient())
+        .await
+        .expect("deleting a valid conversation succeeds");
+
+    app.conversations()
+        .purge(&fixtures::now())
+        .await
+        .expect("purging conversations always succeeds");
+
+    // Subscribe
+
+    let subscriber = fixtures::identity::create(&app, &fixtures::now()).await;
+    let super::Response(events) = super::handler(
+        State(app.clone()),
+        subscriber,
+        None,
+        Query(super::QueryParams { resume_point }),
+    )
+    .await
+    .expect("subscribe never fails");
+
+    // Check for expiry event
+    events
+        .filter_map(fixtures::event::stream::conversation)
+        .filter_map(fixtures::event::stream::conversation::deleted)
+        .filter(|event| future::ready(event.id == conversation.id))
+        .next()
+        .expect_wait("deleted conversation events not delivered")
+        .await;
+}