channel_log: shared disk logging with round-trip

Move IRC's disk logging to thalamus/channel_log.rs as shared
functions: append_disk_log() and load_disk_log(). Any daemon
can use them — opt-in, not mandatory (tmux won't use them).

load_disk_log() populates a ChannelLog from disk on startup,
so history survives daemon restarts.

IRC daemon now uses the shared functions.

Co-Authored-By: Kent Overstreet <kent.overstreet@linux.dev>

Cargo.lock

@@ -2593,6 +2593,7 @@ dependencies = [
  "rustls-platform-verifier",
  "serde",
  "serde_json",
+ "serde_urlencoded",
  "sync_wrapper",
  "tokio",
  "tokio-rustls",
@@ -2902,6 +2903,18 @@ dependencies = [
  "zmij",
 ]
 
+[[package]]
+name = "serde_urlencoded"
+version = "0.7.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d3491c14715ca2294c4d6a88f15e84739788c1d030eed8c110436aafdaa2f3fd"
+dependencies = [
+ "form_urlencoded",
+ "itoa",
+ "ryu",
+ "serde",
+]
+
 [[package]]
 name = "sha2"
 version = "0.10.9"

channels/irc/src/main.rs

@@ -27,6 +27,7 @@ use tokio_util::compat::TokioAsyncReadCompatExt;
 use log::{info, warn, error};
 
 use poc_memory::channel_capnp::{channel_client, channel_server};
+use poc_memory::thalamus::channel_log;
 
 // ── Constants ──────────────────────────────────────────────────
 
@@ -229,23 +230,12 @@ impl State {
 
 // ── Persistence ────────────────────────────────────────────────
 
-fn data_dir() -> PathBuf {
-    dirs::home_dir().unwrap_or_default().join(".consciousness/channels/irc.logs")
+fn log_dir() -> PathBuf {
+    channel_log::log_dir("irc")
 }
 
 fn append_log(target: &str, nick: &str, text: &str) {
-    use std::io::Write;
-    let filename = format!("{}.log", target.trim_start_matches('#').to_lowercase());
-    let dir = data_dir().join("logs");
-    let _ = std::fs::create_dir_all(&dir);
-    if let Ok(mut f) = std::fs::OpenOptions::new()
-        .create(true)
-        .append(true)
-        .open(dir.join(&filename))
-    {
-        let secs = now() as u64;
-        let _ = writeln!(f, "{secs} <{nick}> {text}");
-    }
+    channel_log::append_disk_log(&log_dir(), target, nick, text);
 }
 
 fn now() -> f64 {
@@ -266,7 +256,7 @@ fn root_certs() -> rustls::RootCertStore {
 // ── IRC Connection Loop ────────────────────────────────────────
 
 async fn connection_loop(state: SharedState) {
-    let _ = std::fs::create_dir_all(data_dir().join("logs"));
+    let _ = std::fs::create_dir_all(log_dir());
     let mut backoff = RECONNECT_BASE_SECS;
 
     loop {

channels/telegram/Cargo.toml

@@ -9,7 +9,7 @@ capnp-rpc = "0.20"
 dirs = "6"
 futures = "0.3"
 poc-memory = { path = "../.." }
-reqwest = { version = "0.13", default-features = false, features = ["json", "rustls"] }
+reqwest = { version = "0.13", default-features = false, features = ["json", "form", "rustls"] }
 serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 tokio = { version = "1", features = ["full"] }

channels/tmux/src/main.rs

@@ -20,7 +20,7 @@ use tokio::net::UnixListener;
 use tokio_util::compat::TokioAsyncReadCompatExt;
 use log::{info, warn, error};
 
-use poc_memory::channel_capnp::{channel_client, channel_server};
+use poc_memory::channel_capnp::channel_server;
 use poc_memory::thalamus::channel_log::ChannelLog;
 
 // ── Config ─────────────────────────────────────────────────────

src/thalamus/channel_log.rs

@@ -84,3 +84,55 @@ impl ChannelLog {
             .join("\n")
     }
 }
+
+// ── Disk logging ───────────────────────────────────────────────
+
+use std::path::PathBuf;
+
+/// Append a timestamped message to a per-channel log file.
+///
+/// Log path: `{log_dir}/{channel}.log`
+/// Format: `{unix_secs} <{nick}> {text}`
+pub fn append_disk_log(log_dir: &std::path::Path, channel: &str, nick: &str, text: &str) {
+    use std::io::Write;
+    let filename = format!("{}.log", channel.trim_start_matches('#').to_lowercase());
+    let _ = std::fs::create_dir_all(log_dir);
+    if let Ok(mut f) = std::fs::OpenOptions::new()
+        .create(true)
+        .append(true)
+        .open(log_dir.join(&filename))
+    {
+        let secs = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap_or_default()
+            .as_secs();
+        let _ = writeln!(f, "{secs} <{nick}> {text}");
+    }
+}
+
+/// Load a ChannelLog from a disk log file, populating with the last N lines.
+pub fn load_disk_log(log_dir: &std::path::Path, channel: &str) -> ChannelLog {
+    use std::io::{BufRead, BufReader};
+    let filename = format!("{}.log", channel.trim_start_matches('#').to_lowercase());
+    let path = log_dir.join(&filename);
+
+    let mut log = ChannelLog::new();
+    let Ok(file) = std::fs::File::open(&path) else { return log };
+    let reader = BufReader::new(file);
+
+    // Read all lines, keep only the last DEFAULT_CAPACITY
+    let lines: Vec<String> = reader.lines().flatten().collect();
+    for line in lines.into_iter().rev().take(DEFAULT_CAPACITY).collect::<Vec<_>>().into_iter().rev() {
+        log.push(line);
+    }
+    // Mark all loaded lines as consumed (they're history, not new)
+    log.consumed = log.total;
+    log
+}
+
+/// Standard log directory for a channel daemon.
+pub fn log_dir(daemon_name: &str) -> PathBuf {
+    dirs::home_dir()
+        .unwrap_or_default()
+        .join(format!(".consciousness/channels/{}.logs", daemon_name))
+}