rename claude.md to agents.md for agents and the repo

Claude Code (>= 2.1.277) and opencode both read AGENTS.md, but Claude
Code reads it only when no CLAUDE.md exists in its cwd or above. So
this is a plain rename with no CLAUDE.md stub left behind.

- hive-agent/src/agents_md_migrate.rs: new. At harness start, before
  the first turn, renames state/CLAUDE.md to state/AGENTS.md when only
  the former exists; logs an error naming both paths when both exist
  and touches neither; does nothing otherwise. Idempotent.
- hive-agent/src/main.rs: calls it in serve_main; checkpoint prompt
  and a comment name AGENTS.md.
- hive-agent/src/claude_md_watch.rs: the size watch reads AGENTS.md;
  todo text, doc comments and tests follow. Module name, todo
  subsystem key ("claude_md") and metric name
  (hyperhive.agent.claude_md.lines) are unchanged so existing todo
  rows and dashboard history carry over.
- hive-agent/src/turn.rs, hive-agent/prompts/system.md: prompts tell
  the agent its file is AGENTS.md.
- hive-agent/src/{otel_turn_metrics,stats}.rs,
  frontend/packages/agent/src/stats.js, hive-subagent-mcp/src/*.rs:
  comments and a tool parameter description naming the agent's file.
- nix/host-modules/swarm-grafana/dashboards/agents.json: panel title
  and description.
- claude-plugins skills claude-subagents, state-hygiene: they mean the
  agent's own state file.
- CLAUDE.md -> AGENTS.md at the repo root; docs/crates/README.md link
  (checked by check-doc-refs.sh), hive-c0re/README.md,
  .prettierignore and the nix/sources.nix comment follow.
- docs/: every prose mention of the agent's file; persistence.md
  documents the boot-time rename, claude-invocation.md the shadowing.

Fixes #5509

hive-agent/src/agents_md_migrate.rs

@@ -0,0 +1,143 @@
+//! One-time on-boot rename of the agent's instructions file from
+//! `state/CLAUDE.md` to `state/AGENTS.md`. Runs in `main.rs` before the
+//! first turn. Idempotent: once the file is renamed, later boots find no
+//! `CLAUDE.md` and do nothing.
+//!
+//! Claude Code reads `AGENTS.md` only when no `CLAUDE.md` exists in its cwd
+//! or above, so a `CLAUDE.md` left next to an `AGENTS.md` shadows it. When
+//! both exist this module refuses to choose: it logs an error naming both
+//! paths and leaves the files alone for the agent or operator to merge.
+
+use std::path::{Path, PathBuf};
+
+use anyhow::{Context, Result};
+
+/// What [`rename_claude_md`] found and did.
+#[derive(Debug, PartialEq, Eq)]
+pub enum Outcome {
+    /// `CLAUDE.md` existed without an `AGENTS.md`, and is now `AGENTS.md`.
+    Renamed,
+    /// Neither file, or only `AGENTS.md`: nothing to do.
+    NothingToDo,
+    /// Both files exist; neither was touched.
+    BothExist {
+        claude_md: PathBuf,
+        agents_md: PathBuf,
+    },
+}
+
+/// Rename `<state_dir>/CLAUDE.md` to `<state_dir>/AGENTS.md` if only the
+/// former exists. Logs the outcome; never fatal to boot.
+pub fn run(state_dir: &Path) {
+    match rename_claude_md(state_dir) {
+        Ok(Outcome::Renamed) => {
+            tracing::info!(dir = %state_dir.display(), "renamed CLAUDE.md to AGENTS.md");
+        }
+        Ok(Outcome::NothingToDo) => {}
+        Ok(Outcome::BothExist {
+            claude_md,
+            agents_md,
+        }) => tracing::error!(
+            claude_md = %claude_md.display(),
+            agents_md = %agents_md.display(),
+            "both CLAUDE.md and AGENTS.md exist; claude loads only CLAUDE.md while it exists. \
+             Merge them into AGENTS.md and delete CLAUDE.md"
+        ),
+        Err(e) => tracing::error!(error = ?e, "CLAUDE.md to AGENTS.md rename failed"),
+    }
+}
+
+/// Decide and apply the rename.
+///
+/// # Errors
+///
+/// Propagates a failed `rename`; both files are left as they were.
+pub fn rename_claude_md(state_dir: &Path) -> Result<Outcome> {
+    let claude_md = state_dir.join("CLAUDE.md");
+    let agents_md = state_dir.join("AGENTS.md");
+    match (claude_md.exists(), agents_md.exists()) {
+        (true, false) => {
+            std::fs::rename(&claude_md, &agents_md).with_context(|| {
+                format!("rename {} -> {}", claude_md.display(), agents_md.display())
+            })?;
+            Ok(Outcome::Renamed)
+        }
+        (true, true) => Ok(Outcome::BothExist {
+            claude_md,
+            agents_md,
+        }),
+        (false, _) => Ok(Outcome::NothingToDo),
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn claude_md_alone_is_renamed_once() {
+        let dir = tempfile::tempdir().expect("tempdir");
+        std::fs::write(dir.path().join("CLAUDE.md"), "me\n").expect("write");
+
+        assert_eq!(rename_claude_md(dir.path()).expect("run"), Outcome::Renamed);
+        assert!(!dir.path().join("CLAUDE.md").exists());
+        assert_eq!(
+            std::fs::read_to_string(dir.path().join("AGENTS.md")).expect("read"),
+            "me\n"
+        );
+
+        assert_eq!(
+            rename_claude_md(dir.path()).expect("second run"),
+            Outcome::NothingToDo
+        );
+        assert_eq!(
+            std::fs::read_to_string(dir.path().join("AGENTS.md")).expect("read"),
+            "me\n"
+        );
+    }
+
+    #[test]
+    fn both_present_touches_neither() {
+        let dir = tempfile::tempdir().expect("tempdir");
+        let claude_md = dir.path().join("CLAUDE.md");
+        let agents_md = dir.path().join("AGENTS.md");
+        std::fs::write(&claude_md, "old\n").expect("write");
+        std::fs::write(&agents_md, "new\n").expect("write");
+
+        assert_eq!(
+            rename_claude_md(dir.path()).expect("run"),
+            Outcome::BothExist {
+                claude_md: claude_md.clone(),
+                agents_md: agents_md.clone(),
+            }
+        );
+        assert_eq!(std::fs::read_to_string(&claude_md).expect("read"), "old\n");
+        assert_eq!(std::fs::read_to_string(&agents_md).expect("read"), "new\n");
+    }
+
+    #[test]
+    fn neither_present_creates_nothing() {
+        let dir = tempfile::tempdir().expect("tempdir");
+
+        assert_eq!(
+            rename_claude_md(dir.path()).expect("run"),
+            Outcome::NothingToDo
+        );
+        assert_eq!(std::fs::read_dir(dir.path()).expect("ls").count(), 0);
+    }
+
+    #[test]
+    fn agents_md_alone_is_left_alone() {
+        let dir = tempfile::tempdir().expect("tempdir");
+        std::fs::write(dir.path().join("AGENTS.md"), "me\n").expect("write");
+
+        assert_eq!(
+            rename_claude_md(dir.path()).expect("run"),
+            Outcome::NothingToDo
+        );
+        assert_eq!(
+            std::fs::read_to_string(dir.path().join("AGENTS.md")).expect("read"),
+            "me\n"
+        );
+    }
+}

hive-agent/src/claude_md_watch.rs

@@ -1,5 +1,5 @@
-//! `CLAUDE.md` size watch: raises a loose-ends-v2 todo when the agent's
-//! own `CLAUDE.md` grows past 500 lines, and feeds the same line count
+//! `AGENTS.md` size watch: raises a loose-ends-v2 todo when the agent's
+//! own `AGENTS.md` grows past 500 lines, and feeds the same line count
 //! into an OTEL gauge every tick regardless of threshold. Per the
 //! operator's own framing of the ask — "claude md is personality and
 //! how you organize yourself, not a work log" — the prompt is asked to
@@ -11,7 +11,7 @@
 //! summary) — a third instance of the same anti-nag pattern rather than
 //! a new one.
 //!
-//! `CLAUDE.md` lives at the top of the agent's own state dir — the same
+//! `AGENTS.md` lives at the top of the agent's own state dir — the same
 //! directory `claude --print` runs with as its cwd (`turn::session_cwd`),
 //! which is how the CLI's own auto-load discovers it.
 //!
@@ -40,20 +40,24 @@ const WARN_LINES: u64 = 500;
 const BUCKET: u64 = 50;
 /// Producing subsystem marker for the todo row.
 const SUBSYSTEM: &str = "claude_md";
-/// Fixed dedup key — there is only ever one `CLAUDE.md`-size todo per
+/// Fixed dedup key — there is only ever one `AGENTS.md`-size todo per
 /// agent.
 const TODO_KEY: &str = "size";
 
-/// Background loop: periodically reconcile the `CLAUDE.md`-size todo and
+/// Background loop: periodically reconcile the `AGENTS.md`-size todo and
 /// feed the OTEL gauge. Detached task — runs for the harness's lifetime;
 /// errors are logged, never fatal.
 pub async fn run(todos: Arc<Todos>, wake: Arc<Notify>) {
     loop {
         tokio::time::sleep(CHECK_INTERVAL).await;
-        let lines = match tokio::task::spawn_blocking(|| line_count(&claude_md_path())).await {
+        let lines = match tokio::task::spawn_blocking(|| {
+            line_count(&agents_md_path(&crate::paths::state_dir()))
+        })
+        .await
+        {
             Ok(l) => l,
             Err(e) => {
-                tracing::warn!(error = %e, "claude.md watch probe panicked");
+                tracing::warn!(error = %e, "agents.md watch probe panicked");
                 continue;
             }
         };
@@ -72,25 +76,25 @@ fn reconcile(todos: &Todos, wake: &Notify, summary: Option<&str>) {
         Some(summary) => match todos.upsert(SUBSYSTEM, Some(TODO_KEY), summary, None, false) {
             Ok((_, true)) => wake.notify_one(),
             Ok((_, false)) => {}
-            Err(e) => tracing::warn!(error = ?e, "claude.md todo upsert failed"),
+            Err(e) => tracing::warn!(error = ?e, "agents.md todo upsert failed"),
         },
         None => {
             if let Err(e) = todos.clear(SUBSYSTEM, Some(TODO_KEY)) {
-                tracing::warn!(error = ?e, "claude.md todo clear failed");
+                tracing::warn!(error = ?e, "agents.md todo clear failed");
             }
         }
     }
 }
 
-/// `CLAUDE.md`'s path: the top of the agent's own state dir, matching
+/// `AGENTS.md`'s path: the top of the agent's own state dir, matching
 /// where `claude --print` runs (`turn::session_cwd`) and therefore where
 /// its own auto-load discovers the file.
-fn claude_md_path() -> std::path::PathBuf {
-    crate::paths::state_dir().join("CLAUDE.md")
+fn agents_md_path(state_dir: &Path) -> std::path::PathBuf {
+    state_dir.join("AGENTS.md")
 }
 
 /// Line count of the file at `path`. `None` when it can't be read — no
-/// `CLAUDE.md` yet is not a warning, and a transient read failure isn't
+/// `AGENTS.md` yet is not a warning, and a transient read failure isn't
 /// either.
 fn line_count(path: &Path) -> Option<u64> {
     let contents = std::fs::read_to_string(path).ok()?;
@@ -108,9 +112,9 @@ fn summary_for(lines: u64) -> Option<String> {
     }
     let bucket = lines / BUCKET * BUCKET;
     Some(format!(
-        "your CLAUDE.md is {bucket}+ lines. CLAUDE.md is personality and how you organize \
+        "your AGENTS.md is {bucket}+ lines. AGENTS.md is personality and how you organize \
          yourself, not a work log — if it's grown past that, moving detail into separate files \
-         (linked from CLAUDE.md) or an archive is what actually shrinks this count. It \
+         (linked from AGENTS.md) or an archive is what actually shrinks this count. It \
          auto-loads into every turn, so a smaller file is a fixed cost saved on every turn. \
          Nothing here is a hard limit, and deleting stale content outright is fine too if \
          that's genuinely what it is — no obligation either way. No need to act on this now — \
@@ -175,16 +179,28 @@ mod tests {
     #[test]
     fn line_count_matches_editor_expectations() {
         let dir = tempfile::tempdir().expect("tempdir");
-        let path = dir.path().join("CLAUDE.md");
+        let path = dir.path().join("AGENTS.md");
         // Three lines, trailing newline — an editor shows 3 lines, not 4.
         std::fs::write(&path, "one\ntwo\nthree\n").expect("write");
         assert_eq!(line_count(&path), Some(3));
     }
 
+    /// The watch counts `AGENTS.md`, and a leftover `CLAUDE.md` beside it
+    /// is not what it reads.
+    #[test]
+    fn watch_reads_agents_md_not_claude_md() {
+        let dir = tempfile::tempdir().expect("tempdir");
+        std::fs::write(dir.path().join("CLAUDE.md"), "one\n").expect("write");
+        assert_eq!(line_count(&agents_md_path(dir.path())), None);
+
+        std::fs::write(dir.path().join("AGENTS.md"), "one\ntwo\n").expect("write");
+        assert_eq!(line_count(&agents_md_path(dir.path())), Some(2));
+    }
+
     #[test]
     fn missing_file_is_silent_not_an_error() {
         assert_eq!(
-            line_count(Path::new("/definitely/does/not/exist/CLAUDE.md")),
+            line_count(Path::new("/definitely/does/not/exist/AGENTS.md")),
             None
         );
     }

hive-agent/src/main.rs

@@ -9,6 +9,7 @@
 //! Single bin crate: the module tree below (formerly this crate's `lib.rs`,
 //! before lib + bin were collapsed into one) plus the serve loop.
 
+mod agents_md_migrate;
 mod boot_announce;
 mod claude_credentials;
 mod claude_md_watch;
@@ -215,7 +216,7 @@ fn graceful_stop_message() -> hive_sh4re::inbox::DeliveredMessage {
         body: "You are being gracefully stopped — the container will shut down after this turn, \
                and new inbound messages are already fenced. This is your one checkpoint turn: \
                flush anything worth keeping into your durable /state files now — update your \
-               notes / CLAUDE.md / TODO.md with in-flight task state, decisions made, important \
+               notes / AGENTS.md / TODO.md with in-flight task state, decisions made, important \
                file paths, and whatever you'd need to resume cleanly later with only a summary \
                of this conversation to go on. Do not start new work or reply to anyone; just \
                write your notes and end your turn. The session may be compacted after this turn \
@@ -450,7 +451,7 @@ fn spawn_todo_socket(
             // top level instead of disk pressure.
             tokio::spawn(state_entry_watch::run(store.clone(), todo_wake.clone()));
             // Same shape again: nudge (and feed an OTEL gauge) on a
-            // grown CLAUDE.md instead of a grown state dir.
+            // grown AGENTS.md instead of a grown state dir.
             tokio::spawn(claude_md_watch::run(store.clone(), todo_wake.clone()));
             // Swarm-scheduled prompts fire as todos too, from the list the
             // swarm keeps for this agent.
@@ -553,6 +554,8 @@ async fn serve_main<S: Surface>(socket: &Path, poll_ms: u64) -> Result<()> {
             tracing::error!(error = %e, "web_ui::serve exited with error");
         }
     });
+    // Before the first turn, so claude's own auto-load finds `AGENTS.md`.
+    agents_md_migrate::run(&paths::state_dir());
     // Harness-local reminders: a due reminder fires
     // straight into an mpsc channel the serve loop races against the
     // broker long-poll (unlike todos, a fire carries real per-row data,

hive-agent/src/otel_turn_metrics.rs

@@ -53,7 +53,7 @@ struct Instruments {
     open_threads: Gauge<u64>,
     open_reminders: Gauge<u64>,
     /// Recorded from [`crate::claude_md_watch`]'s own tick, not from
-    /// [`record`] — `CLAUDE.md` size is a continuously-live value (like
+    /// [`record`] — `AGENTS.md` size is a continuously-live value (like
     /// hive-c0re's container gauges), not a once-per-turn one, so it has
     /// its own entry point rather than riding `record`'s per-turn call.
     claude_md_lines: Gauge<u64>,
@@ -110,7 +110,7 @@ pub fn record(row: &TurnStatRow, fresh_session: bool) {
     }
 }
 
-/// Record the current `CLAUDE.md` line count. Called from
+/// Record the current `AGENTS.md` line count. Called from
 /// [`crate::claude_md_watch`]'s periodic tick (every ~15 minutes, not
 /// per turn) — see the field doc on [`Instruments::claude_md_lines`] for
 /// why this doesn't ride [`record`]. No-op when OTEL isn't configured,

hive-agent/src/stats.rs

@@ -142,7 +142,7 @@ pub struct Snapshot {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub reminder_stats: Option<ReminderStats>,
     /// First-turn input tokens of the most recent fresh claude session
-    /// that started in the window — a proxy for system-prompt + CLAUDE.md
+    /// that started in the window — a proxy for system-prompt + AGENTS.md
     /// sprawl (a fresh session's first turn pays the full static prefix
     /// uncached, so this is the current "cold context" cost). `None` until
     /// the sessions capture (per-session `session_id`) has data; every
@@ -379,7 +379,7 @@ fn snapshot(path: &Path, window: Window) -> Result<Snapshot> {
 }
 
 /// First-turn input tokens of the most recent fresh claude session that
-/// started in `[from, now]`. Tracks system-prompt + CLAUDE.md sprawl:
+/// started in `[from, now]`. Tracks system-prompt + AGENTS.md sprawl:
 /// the first turn of a fresh session (`--continue` suppressed) pays the
 /// full static prefix as uncached input, so watching this over time
 /// surfaces creep. Uses the agreed per-session derive — the first turn

hive-agent/src/turn.rs

@@ -81,7 +81,7 @@ Your conversation context has grown large and the harness is about to run `/comp
 which collapses the detailed turn-by-turn history into a short summary. Anything you \
 do not persist now is effectively lost after the next turn.\n\n\
 Use THIS turn to flush anything worth keeping into your durable `/state` files: update \
-your notes / CLAUDE.md / TODO.md with in-flight task state, decisions made, important \
+your notes / AGENTS.md / TODO.md with in-flight task state, decisions made, important \
 file paths, and whatever you would need to resume cleanly with only a summary of this \
 conversation to go on. Do not start new work or reply to anyone — just write your notes \
 and end the turn.";