Port live DDIR server to current interpreter

Cargo.toml

@@ -5,6 +5,7 @@ members = [
     "dogsdogsdogs",
     "experiments",
     "interactive",
+    "interactive/server",
     "server",
     "server/dataflows/degr_dist",
     "server/dataflows/neighborhood",

interactive/server/Cargo.toml

@@ -0,0 +1,21 @@
+[package]
+name = "ddir-server"
+version = "0.1.0"
+edition.workspace = true
+rust-version.workspace = true
+description = "Interactive differential dataflow server: hold named arrangements live across DDIR program installs and drops."
+publish = false
+
+[[bin]]
+name = "ddir_server"
+path = "src/main.rs"
+
+[lints]
+workspace = true
+
+[dependencies]
+differential-dataflow = { workspace = true }
+timely = { workspace = true }
+interactive = { path = ".." }
+diagnostics = { path = "../../diagnostics" }
+tungstenite = "0.26"

interactive/server/README.md

@@ -0,0 +1,39 @@
+# Live DDIR server
+
+This crate transports the earlier `ddir-server` prototype onto the current
+scope-tree DDIR interpreter. It does not use dynamic loading or a Rust FFI.
+
+Run `cargo run -p ddir-server`, then open `interactive/server/console.html` or
+connect a line-oriented client to TCP port 7777. The same protocol is available
+over WebSocket on port 7778. Set `DDIR_BIND`, `DDIR_WS_BIND`, or
+`DDIR_TICK_MS` to change those defaults; `DDIR_TICK_MS=0` disables automatic
+progress while subscriptions are active. The current `diagnostics` crate is
+connected on `DDIR_DIAG_PORT` (default 51371).
+
+Every request can begin with an arbitrary request id. If omitted, the server
+generates one. Responses are `<id> data ...`, followed by `<id> ok ...` or
+`<id> err ...`. A `tail` remains active after its `ok` and ends when stopped.
+
+The useful commands are `load`, `drop`, `list`, `peek`, `tail`, `stop`, `tick`,
+and `exit`. `load` accepts an inline pipe-syntax program:
+
+    load graph begin
+    let edges = import "random:nodes=8,edges=12,seed=1,churn=1";
+    export "graph.edges" = edges;
+    graph end-load
+    tail graph.edges
+
+The old binding spelling is also accepted during upload, so
+`edges=random(seed=1,arity=2,range=8,count=12,churn=1)` can redirect the local
+import named `edges`. It is translated to the current content-addressed source
+name. Such a source is deterministic: it begins with a fixed-size window into
+an infinite hash-derived sequence and replaces `churn` rows on every tick.
+
+Automatic ticking happens only while at least one tail is active. This makes a
+live demonstration move without assigning input durability semantics to DDIR.
+Explicit `tick [n]` remains available for reproducible sessions.
+
+The prototype's `--explain`/`query` path is intentionally not ported yet. It was
+tied to the former flat IR and should instead be rebuilt around the current
+scope-tree explanation work. The live server reports an error rather than
+silently changing those commands' meaning.