hyperhive/hive-c0re/src/dashboard.rs

//! Hyperhive dashboard. Lists managed containers (with deep-links to each
//! container's web UI), pending approvals (with unified diff vs the applied
//! repo, plus approve/deny buttons), and the manager.

use std::convert::Infallible;
use std::fmt::Write as _;
use std::net::SocketAddr;
use std::path::Path;
use std::sync::Arc;

use anyhow::{Context, Result};
use axum::extract::Form;
use axum::{
    Router,
    extract::{Path as AxumPath, State},
    http::{HeaderMap, StatusCode},
    response::{
        Html, IntoResponse, Redirect, Response,
        sse::{Event, KeepAlive, Sse},
    },
    routing::{get, post},
};
use hive_sh4re::Approval;
use serde::{Deserialize, Serialize};
use tokio_stream::wrappers::BroadcastStream;
use tokio_stream::{Stream, StreamExt};

use crate::actions;
use crate::coordinator::Coordinator;
use crate::lifecycle::{self, AGENT_PREFIX, MANAGER_NAME};

const MANAGER_PORT: u16 = 8000;

#[derive(Clone)]
struct AppState {
    coord: Arc<Coordinator>,
}

pub async fn serve(port: u16, coord: Arc<Coordinator>) -> Result<()> {
    let app = Router::new()
        .route("/", get(serve_index))
        .route("/static/dashboard.css", get(serve_css))
        .route("/static/app.js", get(serve_app_js))
        .route("/api/state", get(api_state))
        .route("/approve/{id}", post(post_approve))
        .route("/deny/{id}", post(post_deny))
        .route("/destroy/{name}", post(post_destroy))
        .route("/kill/{name}", post(post_kill))
        .route("/restart/{name}", post(post_restart))
        .route("/start/{name}", post(post_start))
        .route("/rebuild/{name}", post(post_rebuild))
        .route("/update-all", post(post_update_all))
        .route("/answer-question/{id}", post(post_answer_question))
        .route("/purge-tombstone/{name}", post(post_purge_tombstone))
        .route("/request-spawn", post(post_request_spawn))
        .route("/messages/stream", get(messages_stream))
        .with_state(AppState { coord });
    let addr = SocketAddr::from(([0, 0, 0, 0], port));
    let listener = tokio::net::TcpListener::bind(addr)
        .await
        .with_context(|| format!("bind dashboard on port {port}"))?;
    tracing::info!(%port, "dashboard listening");
    axum::serve(listener, app).await?;
    Ok(())
}

// ---------------------------------------------------------------------------
// Static asset handlers: the dashboard is an SPA. `GET /` returns the
// (static) shell; `GET /static/*` serves the CSS + JS app; `GET /api/state`
// returns the current snapshot as JSON. The JS app fetches state on load,
// re-fetches after every async-form submit, and listens on
// `/messages/stream` for broker traffic.
// ---------------------------------------------------------------------------

async fn serve_index() -> impl IntoResponse {
    Html(include_str!("../assets/index.html"))
}

async fn serve_css() -> impl IntoResponse {
    (
        [("content-type", "text/css")],
        include_str!("../assets/dashboard.css"),
    )
}

async fn serve_app_js() -> impl IntoResponse {
    (
        [("content-type", "application/javascript")],
        include_str!("../assets/app.js"),
    )
}

#[derive(Serialize)]
struct StateSnapshot {
    hostname: String,
    manager_port: u16,
    any_stale: bool,
    containers: Vec<ContainerView>,
    transients: Vec<TransientView>,
    approvals: Vec<ApprovalView>,
    /// Latest messages addressed to `operator` — surfaces agent replies
    /// asynchronously so the operator can see them without watching the
    /// live panel during a turn.
    operator_inbox: Vec<crate::broker::InboxRow>,
    /// Pending operator questions (currently only from the manager).
    /// `ask_operator` returns immediately with the id; on `/answer-question`
    /// we mark the row answered and fire `HelperEvent::OperatorAnswered`
    /// into the manager's inbox.
    questions: Vec<crate::operator_questions::OpQuestion>,
    /// State dirs (config history + claude creds + /state/ notes) that
    /// survive after a destroy-without-purge. The operator can re-spawn
    /// with the same name to resume, or PURG3 to wipe them.
    tombstones: Vec<TombstoneView>,
}

#[derive(Serialize)]
struct TombstoneView {
    name: String,
    /// Bytes used by the state dir tree. Cheap-ish to compute; let the
    /// operator know how much they're holding onto.
    state_bytes: u64,
    /// Mtime (unix seconds) of the state dir; rough "last seen".
    last_seen: i64,
    has_creds: bool,
}

#[derive(Serialize)]
#[allow(clippy::struct_excessive_bools)]
struct ContainerView {
    /// Logical agent name (no `h-` prefix). Used in action URLs.
    name: String,
    /// Container name as nixos-container sees it (`h-foo`, `hm1nd`).
    container: String,
    is_manager: bool,
    port: u16,
    running: bool,
    needs_update: bool,
    needs_login: bool,
    /// When a lifecycle action is in flight on this container, the kind
    /// (`starting`, `stopping`, etc.) so the JS can render a spinner +
    /// disable other buttons.
    #[serde(skip_serializing_if = "Option::is_none")]
    pending: Option<&'static str>,
}

#[derive(Serialize)]
struct TransientView {
    name: String,
    kind: &'static str,
    secs: u64,
}

#[derive(Serialize)]
struct ApprovalView {
    id: i64,
    agent: String,
    kind: &'static str,
    /// First 12 chars of the `commit_ref`, for `ApplyCommit` only.
    sha_short: Option<String>,
    /// Pre-rendered syntax-coloured diff HTML, for `ApplyCommit` only.
    diff_html: Option<String>,
}

async fn api_state(headers: HeaderMap, State(state): State<AppState>) -> axum::Json<StateSnapshot> {
    let host = headers
        .get("host")
        .and_then(|h| h.to_str().ok())
        .unwrap_or("localhost");
    let hostname = host.split(':').next().unwrap_or(host).to_owned();

    let raw_containers = lifecycle::list().await.unwrap_or_default();
    let current_rev = crate::auto_update::current_flake_rev(&state.coord.hyperhive_flake);
    let transient_snapshot = state.coord.transient_snapshot();
    let pending_approvals = gc_orphans(
        &state.coord,
        state.coord.approvals.pending().unwrap_or_default(),
    );

    let (containers, any_stale) =
        build_container_views(&raw_containers, current_rev.as_deref(), &transient_snapshot).await;
    let transients = build_transient_views(&raw_containers, &transient_snapshot);
    let approvals = build_approval_views(pending_approvals).await;
    let tombstones = build_tombstone_views(&state.coord, &containers, &transient_snapshot);

    let operator_inbox = state
        .coord
        .broker
        .recent_for(hive_sh4re::OPERATOR_RECIPIENT, 50)
        .unwrap_or_default();
    let questions = state.coord.questions.pending().unwrap_or_default();

    axum::Json(StateSnapshot {
        hostname,
        manager_port: MANAGER_PORT,
        any_stale,
        containers,
        transients,
        approvals,
        operator_inbox,
        questions,
        tombstones,
    })
}

/// Build `ContainerView`s for every live nixos-container. Returns the
/// list and whether any container is stale (drives the "↻ UPD4TE 4LL"
/// banner).
async fn build_container_views(
    raw_containers: &[String],
    current_rev: Option<&str>,
    transient_snapshot: &std::collections::HashMap<String, crate::coordinator::TransientState>,
) -> (Vec<ContainerView>, bool) {
    let mut out = Vec::new();
    let mut any_stale = false;
    for c in raw_containers {
        let (logical, is_manager) = if c == MANAGER_NAME {
            (MANAGER_NAME.to_owned(), true)
        } else if let Some(n) = c.strip_prefix(AGENT_PREFIX) {
            (n.to_owned(), false)
        } else {
            continue;
        };
        let needs_update =
            current_rev.is_some_and(|rev| crate::auto_update::agent_needs_update(&logical, rev));
        if needs_update {
            any_stale = true;
        }
        let needs_login = !is_manager && !claude_has_session(&Coordinator::agent_claude_dir(&logical));
        let pending = transient_snapshot
            .get(&logical)
            .map(|st| transient_label(st.kind));
        out.push(ContainerView {
            port: lifecycle::agent_web_port(&logical),
            running: lifecycle::is_running(&logical).await,
            container: c.clone(),
            name: logical,
            is_manager,
            needs_update,
            needs_login,
            pending,
        });
    }
    (out, any_stale)
}

/// Transient state for agents whose container does NOT yet exist
/// (`Spawning`). Lifecycle ops on existing containers surface as
/// `ContainerView.pending` inline; this list only catches pre-creation.
fn build_transient_views(
    raw_containers: &[String],
    transient_snapshot: &std::collections::HashMap<String, crate::coordinator::TransientState>,
) -> Vec<TransientView> {
    transient_snapshot
        .iter()
        .filter(|(name, _)| {
            !raw_containers
                .iter()
                .any(|c| c == &format!("{AGENT_PREFIX}{name}") || c == *name)
        })
        .map(|(name, st)| TransientView {
            name: name.clone(),
            kind: transient_label(st.kind),
            secs: st.since.elapsed().as_secs(),
        })
        .collect()
}

/// Render each pending approval into its dashboard view (short sha +
/// unified diff for `ApplyCommit`, just the name for `Spawn`).
async fn build_approval_views(approvals: Vec<Approval>) -> Vec<ApprovalView> {
    let mut out = Vec::with_capacity(approvals.len());
    for a in approvals {
        out.push(match a.kind {
            hive_sh4re::ApprovalKind::ApplyCommit => {
                let sha = a.commit_ref[..a.commit_ref.len().min(12)].to_owned();
                let diff = approval_diff(&a.agent, &a.commit_ref).await;
                ApprovalView {
                    id: a.id,
                    agent: a.agent,
                    kind: "apply_commit",
                    sha_short: Some(sha),
                    diff_html: Some(render_diff_lines(&diff)),
                }
            }
            hive_sh4re::ApprovalKind::Spawn => ApprovalView {
                id: a.id,
                agent: a.agent,
                kind: "spawn",
                sha_short: None,
                diff_html: None,
            },
        });
    }
    out
}

/// State-dir names that don't appear in the live container list (and
/// aren't the manager). Each one surfaces in the dashboard as a row
/// with R3V1V3 + PURG3 actions.
fn build_tombstone_views(
    coord: &Coordinator,
    containers: &[ContainerView],
    transient_snapshot: &std::collections::HashMap<String, crate::coordinator::TransientState>,
) -> Vec<TombstoneView> {
    let _ = coord; // kept_state_names is a free fn but takes &self by future plan
    let live: std::collections::HashSet<&str> = containers
        .iter()
        .map(|c| c.name.as_str())
        .chain(transient_snapshot.keys().map(String::as_str))
        .collect();
    Coordinator::kept_state_names()
        .into_iter()
        .filter(|name| name != MANAGER_NAME && !live.contains(name.as_str()))
        .map(|name| {
            let root = Coordinator::agent_state_root(&name);
            let state_bytes = dir_size_bytes(&root);
            let last_seen = std::fs::metadata(&root)
                .and_then(|m| m.modified())
                .ok()
                .and_then(|t| t.duration_since(std::time::UNIX_EPOCH).ok())
                .and_then(|d| i64::try_from(d.as_secs()).ok())
                .unwrap_or(0);
            let has_creds = claude_has_session(&Coordinator::agent_claude_dir(&name));
            TombstoneView {
                name,
                state_bytes,
                last_seen,
                has_creds,
            }
        })
        .collect()
}

/// Sum the byte size of every regular file under `root`. Cheap to compute
/// for typical agent state (config repo + claude creds + notes file —
/// usually a few MB); fine to do inline on each /api/state. Returns 0 on
/// any error.
fn dir_size_bytes(root: &Path) -> u64 {
    fn walk(p: &Path, acc: &mut u64) {
        let Ok(rd) = std::fs::read_dir(p) else { return };
        for entry in rd.flatten() {
            let Ok(ft) = entry.file_type() else { continue };
            if ft.is_dir() {
                walk(&entry.path(), acc);
            } else if ft.is_file()
                && let Ok(meta) = entry.metadata()
            {
                *acc += meta.len();
            }
        }
    }
    let mut total = 0u64;
    walk(root, &mut total);
    total
}

async fn messages_stream(
    State(state): State<AppState>,
) -> Sse<impl Stream<Item = Result<Event, Infallible>>> {
    let rx = state.coord.broker.subscribe();
    let stream = BroadcastStream::new(rx).filter_map(|res| {
        // Drop lagged events. Browsers reconnect; nothing to do here.
        let event = res.ok()?;
        let json = serde_json::to_string(&event).ok()?;
        Some(Ok(Event::default().data(json)))
    });
    Sse::new(stream).keep_alive(KeepAlive::default())
}

async fn post_approve(State(state): State<AppState>, AxumPath(id): AxumPath<i64>) -> Response {
    match actions::approve(state.coord.clone(), id).await {
        Ok(()) => Redirect::to("/").into_response(),
        Err(e) => error_response(&format!("approve {id} failed: {e:#}")),
    }
}

async fn post_deny(State(state): State<AppState>, AxumPath(id): AxumPath<i64>) -> Response {
    match actions::deny(&state.coord, id) {
        Ok(()) => Redirect::to("/").into_response(),
        Err(e) => error_response(&format!("deny {id} failed: {e:#}")),
    }
}

#[derive(Deserialize)]
struct RequestSpawnForm {
    name: String,
}

#[derive(Deserialize)]
struct AnswerForm {
    answer: String,
}

async fn post_answer_question(
    State(state): State<AppState>,
    AxumPath(id): AxumPath<i64>,
    Form(form): Form<AnswerForm>,
) -> Response {
    let answer = form.answer.trim();
    if answer.is_empty() {
        return error_response("answer: required");
    }
    match state.coord.questions.answer(id, answer) {
        Ok(question) => {
            tracing::info!(%id, "operator answered question");
            state
                .coord
                .notify_manager(&hive_sh4re::HelperEvent::OperatorAnswered {
                    id,
                    question,
                    answer: answer.to_owned(),
                });
            Redirect::to("/").into_response()
        }
        Err(e) => error_response(&format!("answer {id} failed: {e:#}")),
    }
}

async fn post_purge_tombstone(
    State(state): State<AppState>,
    AxumPath(name): AxumPath<String>,
) -> Response {
    if name == lifecycle::MANAGER_NAME {
        return error_response("refusing to purge the manager's state");
    }
    // Sanity: refuse to purge if a live container still exists with this
    // name. The dashboard already filters tombstones to non-live names,
    // but the operator could send a stale POST.
    let live = lifecycle::list().await.unwrap_or_default();
    if live
        .iter()
        .any(|c| c == &format!("{}{name}", lifecycle::AGENT_PREFIX) || c == &name)
    {
        return error_response(&format!(
            "refusing to purge {name}: container still exists — use DESTR0Y first"
        ));
    }
    let mut errors = Vec::new();
    for dir in [
        Coordinator::agent_state_root(&name),
        Coordinator::agent_applied_dir(&name),
    ] {
        if dir.exists()
            && let Err(e) = std::fs::remove_dir_all(&dir)
        {
            errors.push(format!("{}: {e}", dir.display()));
        }
    }
    let _ = state
        .coord
        .approvals
        .fail_pending_for_agent(&name, "agent state purged");
    if errors.is_empty() {
        tracing::info!(%name, "tombstone purged");
        Redirect::to("/").into_response()
    } else {
        error_response(&format!("purge {name} partial: {}", errors.join(", ")))
    }
}

async fn post_request_spawn(
    State(state): State<AppState>,
    Form(form): Form<RequestSpawnForm>,
) -> Response {
    let name = form.name.trim().to_owned();
    if name.is_empty() {
        return error_response("spawn: `name` required");
    }
    match state
        .coord
        .approvals
        .submit_kind(&name, hive_sh4re::ApprovalKind::Spawn, "")
    {
        Ok(id) => {
            tracing::info!(%id, %name, "operator: spawn approval queued via dashboard");
            Redirect::to("/").into_response()
        }
        Err(e) => error_response(&format!("request-spawn {name} failed: {e:#}")),
    }
}

async fn post_rebuild(State(state): State<AppState>, AxumPath(name): AxumPath<String>) -> Response {
    let Some(current_rev) = crate::auto_update::current_flake_rev(&state.coord.hyperhive_flake)
    else {
        return error_response(
            "rebuild: hyperhive_flake has no canonical path; manual rebuild only via `hive-c0re rebuild`",
        );
    };
    let coord = state.coord.clone();
    lifecycle_action(
        &state,
        &name,
        crate::coordinator::TransientKind::Rebuilding,
        "rebuild",
        move |n| {
            let coord = coord.clone();
            let rev = current_rev.clone();
            async move { crate::auto_update::rebuild_agent(&coord, &n, &rev).await }
        },
        |_, _| {},
    )
    .await
}

/// Common shape for the simple lifecycle action handlers (start /
/// stop / restart / rebuild): strip the container prefix, mark
/// transient for the duration so the dashboard can spinner, run the
/// lifecycle op, clear transient, redirect on success or surface the
/// error. `verb` only appears in the error message; `extra` runs on
/// success after `clear_transient` for handlers that need follow-up
/// (e.g. `kill` also unregisters the agent + fires `HelperEvent`).
async fn lifecycle_action<F, Fut>(
    state: &AppState,
    name: &str,
    kind: crate::coordinator::TransientKind,
    verb: &str,
    body: F,
    extra: impl FnOnce(&AppState, &str),
) -> Response
where
    F: FnOnce(String) -> Fut,
    Fut: std::future::Future<Output = anyhow::Result<()>>,
{
    let logical = strip_container_prefix(name);
    state.coord.set_transient(&logical, kind);
    let result = body(logical.clone()).await;
    state.coord.clear_transient(&logical);
    match result {
        Ok(()) => {
            extra(state, &logical);
            Redirect::to("/").into_response()
        }
        Err(e) => error_response(&format!("{verb} {logical} failed: {e:#}")),
    }
}

async fn post_kill(State(state): State<AppState>, AxumPath(name): AxumPath<String>) -> Response {
    let logical = strip_container_prefix(&name);
    if logical == lifecycle::MANAGER_NAME {
        return error_response("kill: refusing to stop the manager");
    }
    lifecycle_action(
        &state,
        &name,
        crate::coordinator::TransientKind::Stopping,
        "kill",
        |n| async move { lifecycle::kill(&n).await },
        |s, n| {
            s.coord.unregister_agent(n);
            s.coord.notify_manager(&hive_sh4re::HelperEvent::Killed {
                agent: n.to_owned(),
            });
        },
    )
    .await
}

async fn post_restart(State(state): State<AppState>, AxumPath(name): AxumPath<String>) -> Response {
    lifecycle_action(
        &state,
        &name,
        crate::coordinator::TransientKind::Restarting,
        "restart",
        |n| async move { lifecycle::restart(&n).await },
        |_, _| {},
    )
    .await
}

async fn post_start(State(state): State<AppState>, AxumPath(name): AxumPath<String>) -> Response {
    lifecycle_action(
        &state,
        &name,
        crate::coordinator::TransientKind::Starting,
        "start",
        |n| async move { lifecycle::start(&n).await },
        |_, _| {},
    )
    .await
}

async fn post_update_all(State(state): State<AppState>) -> Response {
    let Some(current_rev) = crate::auto_update::current_flake_rev(&state.coord.hyperhive_flake)
    else {
        return error_response("update-all: hyperhive_flake has no canonical path");
    };
    let containers = lifecycle::list().await.unwrap_or_default();
    let mut errors = Vec::new();
    for container in containers {
        let logical = if container == lifecycle::MANAGER_NAME {
            lifecycle::MANAGER_NAME.to_owned()
        } else if let Some(n) = container.strip_prefix(lifecycle::AGENT_PREFIX) {
            n.to_owned()
        } else {
            continue;
        };
        if !crate::auto_update::agent_needs_update(&logical, &current_rev) {
            continue;
        }
        if let Err(e) =
            crate::auto_update::rebuild_agent(&state.coord, &logical, &current_rev).await
        {
            errors.push(format!("{logical}: {e:#}"));
        }
    }
    if errors.is_empty() {
        Redirect::to("/").into_response()
    } else {
        error_response(&format!(
            "update-all partial failure:\n{}",
            errors.join("\n")
        ))
    }
}

fn transient_label(k: crate::coordinator::TransientKind) -> &'static str {
    use crate::coordinator::TransientKind::{
        Destroying, Rebuilding, Restarting, Spawning, Starting, Stopping,
    };
    match k {
        Spawning => "spawning",
        Starting => "starting",
        Stopping => "stopping",
        Restarting => "restarting",
        Rebuilding => "rebuilding",
        Destroying => "destroying",
    }
}

/// Convert either a logical name or a container name back to the logical
/// name. Sub-agents are `h-foo` → `foo`; manager stays `hm1nd`.
fn strip_container_prefix(name: &str) -> String {
    name.strip_prefix(lifecycle::AGENT_PREFIX)
        .unwrap_or(name)
        .to_owned()
}

#[derive(Deserialize, Default)]
struct DestroyForm {
    #[serde(default)]
    purge: Option<String>,
}

async fn post_destroy(
    State(state): State<AppState>,
    AxumPath(name): AxumPath<String>,
    Form(form): Form<DestroyForm>,
) -> Response {
    // Checkbox semantics: any non-empty value (axum sends "on") = purge.
    let purge = form.purge.as_deref().is_some_and(|v| !v.is_empty());
    match actions::destroy(&state.coord, &name, purge).await {
        Ok(()) => Redirect::to("/").into_response(),
        Err(e) => error_response(&format!("destroy {name} failed: {e:#}")),
    }
}

fn error_response(message: &str) -> Response {
    // Plain text — the JS app surfaces this in an alert(), so HTML
    // wrapping would just clutter the message.
    (StatusCode::INTERNAL_SERVER_ERROR, message.to_owned()).into_response()
}

/// Filter out approvals whose agent state dir was wiped out from under us
/// (e.g. by a test script's cleanup). Marks them failed so they fall out of
/// `pending` on next render.
fn gc_orphans(coord: &Coordinator, approvals: Vec<Approval>) -> Vec<Approval> {
    approvals
        .into_iter()
        .filter(|a| {
            // Spawn approvals are for not-yet-existent agents; the proposed
            // dir is supposed to be missing.
            if matches!(a.kind, hive_sh4re::ApprovalKind::Spawn) {
                return true;
            }
            if Coordinator::agent_proposed_dir(&a.agent).exists() {
                true
            } else {
                let _ = coord.approvals.mark_failed(a.id, "agent state dir missing");
                tracing::info!(id = a.id, agent = %a.agent, "auto-failed orphan approval");
                false
            }
        })
        .collect()
}

/// Render a unified diff with per-line CSS classes so the dashboard can
/// colour adds / dels / hunk headers / context. Each line becomes a
/// `<span>` tagged by its leading character; the wrapping `<pre>` keeps
/// whitespace intact.
fn render_diff_lines(diff: &str) -> String {
    let mut out = String::new();
    for raw in diff.lines() {
        let cls = match raw.as_bytes().first() {
            // file headers (`--- a/...` / `+++ b/...`) come before any
            // line starting with a single `+`/`-`. similar-rs emits them
            // with the doubled prefix.
            _ if raw.starts_with("--- ") => "diff-file",
            _ if raw.starts_with("+++ ") => "diff-file",
            Some(b'@') => "diff-hunk",
            Some(b'+') => "diff-add",
            Some(b'-') => "diff-del",
            _ => "diff-ctx",
        };
        let _ = writeln!(out, "<span class=\"{cls}\">{}</span>", html_escape(raw),);
    }
    out
}

/// Host-side mirror of `hive_ag3nt::login::has_session`. Returns true if the
/// agent's bound `~/.claude/` dir on disk contains any regular file. The
/// dashboard reads this each render so logins driven from the agent web UI
/// (Phase 8 step 4) reflect within one auto-refresh cycle.
fn claude_has_session(dir: &Path) -> bool {
    let Ok(entries) = std::fs::read_dir(dir) else {
        return false;
    };
    entries
        .flatten()
        .any(|e| e.file_type().is_ok_and(|t| t.is_file()))
}

async fn approval_diff(agent: &str, commit_ref: &str) -> String {
    let proposed = Coordinator::agent_proposed_dir(agent);
    if !proposed.exists() {
        return format!(
            "(proposed dir {} does not exist — agent destroyed?)",
            proposed.display()
        );
    }
    if !proposed.join(".git").exists() {
        return format!("(no git repo at {})", proposed.display());
    }
    let applied = Coordinator::agent_applied_dir(agent).join("agent.nix");
    let applied_text = std::fs::read_to_string(&applied).unwrap_or_default();
    match git_show(&proposed, commit_ref).await {
        Ok(s) => unified_diff(&applied_text, &s),
        Err(e) => format!("(error: {e:#})"),
    }
}

async fn git_show(proposed_dir: &Path, commit_ref: &str) -> Result<String> {
    let out = lifecycle::git_command()
        .current_dir(proposed_dir)
        .args(["show", &format!("{commit_ref}:agent.nix")])
        .output()
        .await
        .with_context(|| {
            format!(
                "spawn `git show` in {} (HYPERHIVE_GIT={})",
                proposed_dir.display(),
                std::env::var("HYPERHIVE_GIT").unwrap_or_else(|_| "<unset>".into()),
            )
        })?;
    if !out.status.success() {
        anyhow::bail!(
            "git show {commit_ref}:agent.nix failed: {}",
            String::from_utf8_lossy(&out.stderr).trim()
        );
    }
    Ok(String::from_utf8_lossy(&out.stdout).into_owned())
}

fn unified_diff(applied: &str, proposed: &str) -> String {
    let diff = similar::TextDiff::from_lines(applied, proposed);
    diff.unified_diff()
        .context_radius(3)
        .header("applied", "proposed")
        .to_string()
}

fn html_escape(s: &str) -> String {
    s.replace('&', "&amp;")
        .replace('<', "&lt;")
        .replace('>', "&gt;")
}