nornir 0.4.46

//! 🏛 **Architecture** tab — the EPIC ARCH wiring board, drawn **natively in
//! egui inside the running viz**.
//!
//! The wiring graph (UI-component ↔ gRPC ↔ core-fn ↔ warehouse-table) already
//! exists as the static circuit-board SVG `nornir arch svg` emits and as the
//! `arch_graph` MCP tool's JSON — but it could not be *viewed in the app*. This
//! pane closes that gap: it reads the persisted [`crate::arch::ArchGraph`] for the
//! active workspace and paints it with egui shapes — nodes coloured by
//! [`crate::arch::NodeKind`] via the active facett palette, edges showing the
//! wiring, navigable (pan/zoom, click a node → highlight its downstream wiring,
//! the same trace `nornir arch trace` computes). It is **egui-native** (no
//! usvg/resvg rasterisation), reusing the DepGraph / CallGraph rendering approach.
//!
//! Source split (mirrors every other pane):
//!   * **local / fat** — open the warehouse directly and
//!     [`merge`](crate::arch::warehouse::merged_arch_from_warehouse) every
//!     member's latest persisted board into one workspace-wide graph.
//!   * **thin / remote** — the server owns the redb lock, so the merge runs
//!     server-side and ships back over the `Viz.Architecture` RPC
//!     ([`crate::viz::remote::fetch_architecture`]).
//!
//! Empty state: if no member has a persisted board yet, the pane shows a clean
//! "run `nornir arch generate`" placeholder — never a hard error, never a TODO.

use std::collections::{BTreeSet, HashMap, VecDeque};
use std::path::PathBuf;
use std::time::Duration;

use eframe::egui::{self, Color32, FontId, Pos2, RichText, ScrollArea, Sense, Stroke, Vec2};
use serde::{Deserialize, Serialize};

#[cfg(test)]
use crate::arch::ArchEdge;
use crate::arch::{ArchEdgeKind, ArchGraph, ArchNode, NodeKind, SymbolLoc};
use crate::coverage::{classify, Boundary};
use crate::viz::trace;

use super::facett_theme::Theme;

/// How often the **Live system** sub-view re-reads the warehouse (repaint-on-
/// change), mirroring `bench_live`/`coverage_live`.
const LIVE_RELOAD_EVERY: Duration = Duration::from_millis(2000);

/// The 🏛 Architecture tab is a CONTAINER: an internal sub-view selector picks
/// which architecture lens to draw. (Deps is rendered by the app — the tab only
/// owns which lens is active so the app routes the dep graph in; the other three
/// are owned + drawn here.)
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ArchSubView {
    /// 🔗 The dependency graph (cross-repo + intra-repo). Drawn by the app
    /// (`draw_dep_graph`) because it needs the timeline; consolidated under Arch.
    Deps,
    /// 📡 The wiring board, warehouse-driven + repaint-on-change.
    Live,
    /// 🏛 The EPIC ARCH wiring board (arch_graph/arch_svg), static.
    Wiring,
    /// 📍 Hållpunkter — the ui / gRPC / emitter LANDMARK functions as nodes.
    Boundaries,
}

impl ArchSubView {
    /// Every sub-view, in selector order — the strip the tab paints + the set the
    /// headless matrix enumerates.
    pub const ALL: [ArchSubView; 4] =
        [ArchSubView::Deps, ArchSubView::Live, ArchSubView::Wiring, ArchSubView::Boundaries];

    /// Stable id (the `state_json` / click contract name).
    pub fn id(self) -> &'static str {
        match self {
            ArchSubView::Deps => "Deps",
            ArchSubView::Live => "Live",
            ArchSubView::Wiring => "Wiring",
            ArchSubView::Boundaries => "Boundaries",
        }
    }

    /// The human label the selector chip paints.
    pub fn label(self) -> &'static str {
        match self {
            ArchSubView::Deps => "🔗 Deps",
            ArchSubView::Live => "📡 Live system",
            ArchSubView::Wiring => "🏛 Wiring",
            ArchSubView::Boundaries => "📍 Hållpunkter",
        }
    }

    fn from_id(s: &str) -> Option<ArchSubView> {
        ArchSubView::ALL.into_iter().find(|v| v.id() == s)
    }
}

/// The decoded `Viz.Architecture` payload (the server's merged board + which
/// members contributed + any per-member load errors). Shared between the embedded
/// warehouse merge and the remote RPC decode, so a thin client renders the exact
/// same graph the fat path produces.
#[derive(Serialize, Deserialize, Clone, Default)]
pub struct ArchPayload {
    pub graph: ArchGraph,
    #[serde(default)]
    pub members_with_data: Vec<String>,
    #[serde(default)]
    pub errors: Vec<String>,
    /// node id → coverage verdict (`"covered"` | `"allowlisted"` | `"missing"`),
    /// cross-checked against the `surface_coverage` matrix: does a test exist for
    /// this marker? Empty when no coverage was recorded. Populated on BOTH the
    /// local (warehouse) and the remote (server) side so thin == fat — the
    /// green/red cross-check is the same warehouse data either way.
    #[serde(default)]
    pub coverage: std::collections::BTreeMap<String, String>,
}

/// Where the graph comes from — a local warehouse (fat) or the server (thin).
enum Src {
    Local(PathBuf),
    Remote { endpoint: String, token: String },
}

/// A laid-out node (graph node + its on-canvas position, before pan/zoom).
struct Laid {
    node: ArchNode,
    pos: Pos2,
}

/// INPUT of an architecture load — which source + workspace was asked for.
#[derive(Serialize)]
struct LoadIn {
    source: String,
    workspace: String,
}

/// OUTPUT of an architecture render — the exact board the user sees, as readable
/// data (LAW #6): counts per kind + edges + which node is selected.
#[derive(Serialize)]
struct RenderOut {
    node_count: usize,
    edge_count: usize,
    components: usize,
    grpc: usize,
    cli: usize,
    core_fns: usize,
    tables: usize,
    /// Markers with a covering test (`surface_coverage` verdict `covered`).
    tested: usize,
    /// Markers in the surface with no test (`missing`) — the red ones.
    untested: usize,
    /// Markers that are known-uncovered but allowlisted (tracked gaps).
    allowlisted: usize,
    /// Markers with no matching coverage row (not claimed either way).
    coverage_unknown: usize,
    selected: Option<String>,
}

pub struct ArchTabState {
    src: Src,
    workspace: String,
    /// `true` once a load has been attempted (so we don't reload every frame).
    loaded: bool,
    /// The merged board to render (empty until loaded / when no member has data).
    graph: ArchGraph,
    /// Members that contributed a board (for the placeholder / status line).
    members_with_data: Vec<String>,
    /// Configured members (for the "which members lack a board" placeholder).
    members: Vec<String>,
    /// Per-member load errors (surfaced; never blank the board).
    errors: Vec<String>,
    /// A human error string if the whole load failed (e.g. RPC down).
    load_error: Option<String>,
    /// Laid-out nodes + adjacency (index space), rebuilt when `graph` changes.
    laid: Vec<Laid>,
    /// id → index into `laid`.
    idx: HashMap<String, usize>,
    /// Forward adjacency over all edge kinds (for the downstream-trace highlight).
    adj: HashMap<usize, Vec<usize>>,
    /// Clicked node (index into `laid`) — highlights its downstream wiring.
    selected: Option<usize>,
    /// The downstream-reachable set from `selected` (BFS), recomputed on click.
    traced: BTreeSet<usize>,
    pan: Vec2,
    zoom: f32,
    /// Edge-trigger for the `architecture.render` trace event (once per data
    /// change / selection change, not once per frame).
    render_dirty: bool,
    /// node id → coverage verdict from the `surface_coverage` matrix
    /// (`"covered"`/`"allowlisted"`/`"missing"`). The cross-check that paints a
    /// marker green (a test exists) or red (none). Empty = no coverage recorded.
    coverage: std::collections::BTreeMap<String, String>,
    theme: Theme,
    // ── container: which sub-view (lens) is active ───────────────────────────
    /// The active sub-view (Deps / Live / Wiring / Hållpunkter).
    sub: ArchSubView,
    // ── click-to-code (the symbol → file:line bridge) ────────────────────────
    /// Local checkout root (`workspace_root/<member>`-ish) used to resolve a
    /// clicked node label to source via a fresh `symbol_facts` scan, and to read
    /// the inline preview window. Empty in remote mode (no checkout → no resolve).
    repo_root: PathBuf,
    /// The repo to scan for symbol resolution (the first configured member).
    resolve_repo: String,
    /// Scanned symbols, lazily loaded the first time a node is clicked (so the
    /// tab doesn't scan on open). `None` until attempted; `Some(vec)` after.
    symbols: Option<Vec<crate::knowledge::symbols::SymbolRow>>,
    /// The last click-to-code resolution: the queried symbol + its `file:line`
    /// candidates (best first). Drives the inline source-preview panel + the
    /// `state_json` last-clicked record + the `architecture.open` trace.
    last_open: Option<OpenResult>,
    /// `true` while the Live sub-view should repaint-on-change (the `live` toggle
    /// parity with bench_live/coverage_live). Reuses `reload()` on the timer.
    live: bool,
    last_live_reload: std::time::Instant,
}

/// One click-to-code resolution — the queried symbol, the resolved candidates,
/// whether the editor was launched, and the inline source-preview window.
#[derive(Clone, Default)]
struct OpenResult {
    query: String,
    hits: Vec<SymbolLoc>,
    /// `Some(true)` opened in editor, `Some(false)` `code` absent, `None` not tried.
    editor_opened: Option<bool>,
    /// The 1-based first line of `preview` + the source lines around the hit.
    preview_start: u32,
    preview: Vec<String>,
}

/// A marker's test-matrix status, derived from its `surface_coverage` verdict.
#[derive(Clone, Copy, PartialEq, Eq)]
enum Cov {
    /// A covering test exists (`verdict = covered`).
    Tested,
    /// Known-uncovered but allowlisted (`verdict = allowlisted`) — a tracked gap.
    Allowlisted,
    /// In the surface, no test (`verdict = missing`) — RED.
    Untested,
    /// No coverage row matched this node — we don't claim either way.
    Unknown,
}

impl Cov {
    fn from_verdict(v: &str) -> Cov {
        match v {
            "covered" => Cov::Tested,
            "allowlisted" => Cov::Allowlisted,
            "missing" => Cov::Untested,
            _ => Cov::Unknown,
        }
    }
    fn label(self) -> &'static str {
        match self {
            Cov::Tested => "tested",
            Cov::Allowlisted => "allowlisted",
            Cov::Untested => "untested",
            Cov::Unknown => "unknown",
        }
    }
}

impl ArchTabState {
    pub fn local(root: PathBuf) -> Self {
        Self::with(Src::Local(root), String::new())
    }
    pub fn remote(endpoint: String, token: String, workspace: String) -> Self {
        Self::with(Src::Remote { endpoint, token }, workspace)
    }
    fn with(src: Src, workspace: String) -> Self {
        Self {
            src,
            workspace,
            loaded: false,
            graph: ArchGraph::default(),
            members_with_data: Vec::new(),
            members: Vec::new(),
            errors: Vec::new(),
            load_error: None,
            laid: Vec::new(),
            idx: HashMap::new(),
            adj: HashMap::new(),
            selected: None,
            traced: BTreeSet::new(),
            pan: Vec2::ZERO,
            zoom: 1.0,
            render_dirty: false,
            coverage: std::collections::BTreeMap::new(),
            theme: Theme::default(),
            sub: ArchSubView::Wiring,
            repo_root: PathBuf::new(),
            resolve_repo: String::new(),
            symbols: None,
            last_open: None,
            live: false,
            last_live_reload: std::time::Instant::now(),
        }
    }

    /// The active sub-view (lens). `pub` so the app routes the Deps lens to the
    /// dep graph + the headless matrix reads which lens is showing.
    pub fn sub_view(&self) -> ArchSubView {
        self.sub
    }

    /// Switch the active sub-view (selector click / robot drive). Emits the
    /// switch as a trace event so it's observable headlessly.
    pub fn set_sub_view(&mut self, sub: ArchSubView) {
        if self.sub != sub {
            self.sub = sub;
            trace::emit_event("architecture.subview", &serde_json::json!({ "sub": sub.id() }));
            self.render_dirty = true;
        }
    }

    /// Seed the local checkout root + the repo to scan for click-to-code symbol
    /// resolution (the inline source preview + `code --goto`). Set by the app on
    /// build/switch; empty in remote mode (no checkout, no resolve).
    pub fn set_resolve_source(&mut self, repo_root: PathBuf, repo: String) {
        if self.repo_root != repo_root || self.resolve_repo != repo {
            self.repo_root = repo_root;
            self.resolve_repo = repo;
            self.symbols = None; // re-scan lazily for the new source
        }
    }

    /// Set the facett palette the pane paints with (C8).
    pub fn set_palette(&mut self, t: Theme) {
        self.theme = t;
    }

    /// The configured workspace members (for the placeholder that names which
    /// members still need `nornir arch generate`). Set by the app on build/switch.
    pub fn set_members(&mut self, members: Vec<String>) {
        self.members = members;
    }

    /// Re-scope to a different workspace (the picker switched): drop the cached
    /// board so the next draw reloads from the new workspace.
    pub fn set_workspace(&mut self, members: Vec<String>) {
        self.members = members;
        self.loaded = false;
        self.graph = ArchGraph::default();
        self.members_with_data.clear();
        self.errors.clear();
        self.load_error = None;
        self.laid.clear();
        self.idx.clear();
        self.adj.clear();
        self.selected = None;
        self.traced.clear();
        self.coverage.clear();
        self.pan = Vec2::ZERO;
        self.zoom = 1.0;
        self.symbols = None;
        self.last_open = None;
    }

    /// Thin mode only: re-point the `Viz.Architecture` RPC at a new workspace.
    pub fn set_workspace_name(&mut self, workspace: String) {
        self.workspace = workspace;
    }

    /// Force a reload on the next draw (e.g. after a ⟳ Sync changed the warehouse).
    pub fn reload(&mut self) {
        self.loaded = false;
    }

    /// Load the merged board: local opens the warehouse + merges every member's
    /// latest board; remote reads the server's merge over `Viz.Architecture`.
    fn ensure_loaded(&mut self) {
        if self.loaded {
            return;
        }
        self.loaded = true;
        let source = match &self.src {
            Src::Local(p) => format!("local {}", p.display()),
            Src::Remote { endpoint, .. } => format!("remote {endpoint} (ws={})", self.workspace),
        };
        trace::emit_in(
            "architecture.load",
            &LoadIn { source, workspace: self.workspace.clone() },
        );
        let payload = match &self.src {
            Src::Local(root) => {
                match crate::warehouse::iceberg::IcebergWarehouse::open(root) {
                    Ok(wh) => {
                        let (graph, with_data, errors) =
                            crate::arch::warehouse::merged_arch_from_warehouse(&wh, &self.members);
                        // Cross-check every marker against the test matrix: read
                        // the workspace's latest surface_coverage and map verdicts
                        // onto the board's node ids — the SAME shared helper the
                        // server's thin path uses, so thin == fat. Same warehouse
                        // the fat board merge already opened.
                        let coverage = crate::arch::warehouse::coverage_for_graph(
                            &wh,
                            &self.workspace,
                            &graph,
                        );
                        Ok(ArchPayload { graph, members_with_data: with_data, errors, coverage })
                    }
                    Err(e) => Err(format!("open warehouse: {e:#}")),
                }
            }
            Src::Remote { endpoint, token } => {
                super::remote::fetch_architecture(endpoint, token, &self.workspace)
                    .map_err(|e| format!("{e:#}"))
            }
        };
        match payload {
            Ok(p) => {
                self.load_error = None;
                self.members_with_data = p.members_with_data;
                self.errors = p.errors;
                self.coverage = p.coverage;
                self.set_graph(p.graph);
            }
            Err(e) => {
                self.load_error = Some(e);
                self.coverage.clear();
                self.set_graph(ArchGraph::default());
            }
        }
    }

    /// This node's test-matrix status (the green/red cross-check).
    fn cov_of(&self, node_id: &str) -> Cov {
        match self.coverage.get(node_id) {
            Some(v) => Cov::from_verdict(v),
            None => Cov::Unknown,
        }
    }

    /// Swap in a new graph + rebuild the layout/adjacency + reset navigation.
    fn set_graph(&mut self, graph: ArchGraph) {
        self.graph = graph;
        self.selected = None;
        self.traced.clear();
        self.pan = Vec2::ZERO;
        self.zoom = 1.0;
        self.build_layout();
        self.render_dirty = true;
    }

    /// Layered layout (PCB-board style, reused from `arch::layers_of`'s model):
    /// columns by topological layer, tables pinned right; positions centred per
    /// column. Pure + deterministic, so the rendered board is stable.
    fn build_layout(&mut self) {
        self.laid.clear();
        self.idx.clear();
        self.adj.clear();
        let layers = layers_of(&self.graph);
        const COL_W: f32 = 230.0;
        const ROW_H: f32 = 64.0;
        let cols = layers.len().max(1) as f32;
        let rows = layers.iter().map(|l| l.len()).max().unwrap_or(1).max(1) as f32;
        let total_w = COL_W * (cols - 1.0).max(0.0);
        let total_h = ROW_H * (rows - 1.0).max(0.0);
        for (ci, layer) in layers.iter().enumerate() {
            let layer_h = ROW_H * (layer.len().saturating_sub(1)) as f32;
            let y0 = -total_h / 2.0 + (total_h - layer_h) / 2.0;
            for (ri, &node_i) in layer.iter().enumerate() {
                let x = -total_w / 2.0 + ci as f32 * COL_W;
                let y = y0 + ri as f32 * ROW_H;
                let node = self.graph.nodes[node_i].clone();
                self.idx.insert(node.id.clone(), self.laid.len());
                self.laid.push(Laid { node, pos: Pos2::new(x, y) });
            }
        }
        // Forward adjacency over all edge kinds, in index space.
        for e in &self.graph.edges {
            if let (Some(&f), Some(&t)) = (self.idx.get(&e.from), self.idx.get(&e.to)) {
                self.adj.entry(f).or_default().push(t);
            }
        }
    }

    /// BFS the downstream-reachable set from a clicked node (the visual twin of
    /// `nornir arch trace` lifted to the laid-out board).
    fn trace_from(&mut self, seed: usize) {
        self.traced.clear();
        let mut q = VecDeque::new();
        self.traced.insert(seed);
        q.push_back(seed);
        while let Some(cur) = q.pop_front() {
            if let Some(outs) = self.adj.get(&cur) {
                for &nxt in outs {
                    if self.traced.insert(nxt) {
                        q.push_back(nxt);
                    }
                }
            }
        }
    }

    /// Lazily scan the configured repo's symbols (the click-to-code source of
    /// truth). Best-effort: in remote mode / with no checkout, leaves `symbols`
    /// an empty vec so resolution returns nothing (the printed `file:line` + the
    /// graph still work; only the inline preview is unavailable).
    fn ensure_symbols(&mut self) {
        if self.symbols.is_some() {
            return;
        }
        if self.repo_root.as_os_str().is_empty() || self.resolve_repo.is_empty() {
            self.symbols = Some(Vec::new());
            return;
        }
        let scan = crate::knowledge::scan_all(&self.repo_root, &self.resolve_repo);
        self.symbols = Some(match scan {
            Ok(s) => s.symbols.symbols,
            Err(_) => Vec::new(),
        });
    }

    /// Click-to-code: resolve a clicked node's `label` (or a typed symbol) to its
    /// source `file:line` via the SHARED [`crate::arch::resolve_symbol`] (the same
    /// bridge `nornir arch open` uses), then (i) open it in the editor
    /// (`code --goto`, best-effort), and (ii) load the inline source-preview
    /// window. The resolution is recorded in `last_open` for the preview panel +
    /// `state_json` + the `architecture.open` trace. Returns whether a hit was
    /// found. `pub` so the robot/CLI-parity drive + tests can fire it directly.
    pub fn open_symbol(&mut self, label: &str, launch_editor: bool) -> bool {
        self.ensure_symbols();
        let syms = self.symbols.as_deref().unwrap_or(&[]);
        let hits = crate::arch::resolve_symbol(syms, label);
        trace::emit_in(
            "architecture.open",
            &serde_json::json!({ "query": label, "candidates": hits.len() }),
        );
        let mut res = OpenResult { query: label.to_string(), hits: hits.clone(), ..Default::default() };
        if let Some(best) = hits.first() {
            // (ii) inline preview window (±6 lines), read from the checkout.
            let root = (!self.repo_root.as_os_str().is_empty()).then_some(self.repo_root.as_path());
            let (start, lines) = crate::arch::source_window(root, &best.file, best.line, 6);
            res.preview_start = start;
            res.preview = lines;
            // (i) best-effort editor launch.
            if launch_editor {
                res.editor_opened = Some(
                    crate::arch::open_in_editor(root, &best.file, best.line).unwrap_or(false),
                );
            }
        }
        let found = !res.hits.is_empty();
        trace::emit_end(
            "architecture.open",
            &serde_json::json!({
                "query": label,
                "resolved": res.hits.first().map(|h| format!("{}:{}", h.file, h.line)),
                "editor_opened": res.editor_opened,
            }),
        );
        self.last_open = Some(res);
        self.render_dirty = true;
        found
    }

    /// Build the **Hållpunkter** (boundary landmark) graph: the ui / gRPC /
    /// emitter functions as LANDMARK nodes, classified by the coverage feature's
    /// [`crate::coverage::classify`] (REUSED, not reinvented), from the scanned
    /// symbols. Each landmark is a node kind-mapped to the board's layers
    /// (ui→Component, grpc→Grpc, emitter→CoreFn) so it paints with the same
    /// legend; edges are omitted (landmarks are anchors, not a call graph).
    fn boundary_landmarks(&self) -> Vec<(Boundary, ArchNode)> {
        let syms = self.symbols.as_deref().unwrap_or(&[]);
        let mut out: Vec<(Boundary, ArchNode)> = Vec::new();
        let mut seen: BTreeSet<String> = BTreeSet::new();
        for s in syms {
            // Build the fully-qualified-ish name the classifier expects.
            let fq = if s.module_path.is_empty() {
                s.item_name.clone()
            } else {
                format!("{}::{}", s.module_path, s.item_name)
            };
            let b = classify(&fq, &s.file);
            if !b.is_boundary() {
                continue;
            }
            let kind = match b {
                Boundary::Ui => NodeKind::Component,
                Boundary::Grpc => NodeKind::Grpc,
                Boundary::Emitter | Boundary::Core => NodeKind::CoreFn,
            };
            let id = format!("{}:{}", b.as_str(), fq);
            if seen.insert(id.clone()) {
                out.push((b, ArchNode { id, label: s.item_name.clone(), kind }));
            }
        }
        out.sort_by(|a, b| a.0.cmp(&b.0).then(a.1.label.cmp(&b.1.label)));
        out
    }

    /// (ui, grpc, emitter) landmark tally for the legend + `state_json`.
    fn boundary_tally(&self) -> (usize, usize, usize) {
        let (mut u, mut g, mut e) = (0, 0, 0);
        for (b, _) in self.boundary_landmarks() {
            match b {
                Boundary::Ui => u += 1,
                Boundary::Grpc => g += 1,
                Boundary::Emitter => e += 1,
                Boundary::Core => {}
            }
        }
        (u, g, e)
    }

    /// The 🏛 Architecture CONTAINER: paints the sub-view selector strip, then
    /// dispatches to the active lens. Deps is drawn by the app (it needs the
    /// timeline) — `draw` returns early for it after the strip, so the app's
    /// `draw_dep_graph` paints the central area; the other three lenses are drawn
    /// here. `draw_deps_for` is never called — the app routes by `sub_view()`.
    pub fn draw(&mut self, ui: &mut egui::Ui) {
        let theme = self.theme;
        // The sub-view selector strip — a chip per lens (Deps / Live / Wiring /
        // Hållpunkter), the active one highlighted. CONSOLIDATES deps under Arch.
        egui::TopBottomPanel::top("arch_subview").show_inside(ui, |ui| {
            ui.horizontal_wrapped(|ui| {
                ui.label(RichText::new("🏛 Architecture").strong().color(theme.text));
                ui.separator();
                for sv in ArchSubView::ALL {
                    if ui.selectable_label(self.sub == sv, sv.label()).clicked() {
                        self.set_sub_view(sv);
                    }
                }
            });
        });

        match self.sub {
            // The app paints the dep graph in the remaining central area after
            // this returns (it owns the timeline) — we leave the space free.
            ArchSubView::Deps => {}
            ArchSubView::Boundaries => self.draw_boundaries(ui),
            ArchSubView::Live | ArchSubView::Wiring => self.draw_board(ui),
        }
    }

    /// The 🏛 Wiring / 📡 Live system lens: the EPIC ARCH wiring board, drawn
    /// natively. Live additionally re-reads the warehouse on a timer + requests a
    /// repaint (repaint-on-change), mirroring bench_live/coverage_live.
    fn draw_board(&mut self, ui: &mut egui::Ui) {
        let theme = self.theme;
        // Live system: timer-driven reload + repaint (warehouse-driven).
        if self.sub == ArchSubView::Live {
            if self.live && self.last_live_reload.elapsed() >= LIVE_RELOAD_EVERY {
                self.loaded = false;
                self.last_live_reload = std::time::Instant::now();
            }
        }
        self.ensure_loaded();

        egui::TopBottomPanel::top("arch_controls").show_inside(ui, |ui| {
            ui.horizontal_wrapped(|ui| {
                ui.heading(if self.sub == ArchSubView::Live { "📡 Live system" } else { "🏛 Wiring" });
                ui.separator();
                ui.label(format!(
                    "{} nodes · {} edges",
                    self.graph.nodes.len(),
                    self.graph.edges.len()
                ));
                ui.separator();
                if ui.button("↻ reload").clicked() {
                    self.loaded = false;
                }
                if ui.button("⊙ fit").clicked() {
                    self.pan = Vec2::ZERO;
                    self.zoom = 1.0;
                }
                if self.selected.is_some() && ui.button("✖ clear selection").clicked() {
                    self.selected = None;
                    self.traced.clear();
                    self.render_dirty = true;
                }
                if self.sub == ArchSubView::Live {
                    ui.separator();
                    ui.checkbox(&mut self.live, "📡 live")
                        .on_hover_text("re-read the warehouse + repaint on change");
                }
                if !self.members_with_data.is_empty() {
                    ui.separator();
                    ui.label(format!("members: {}", self.members_with_data.join(", ")));
                }
            });
            // The kind legend (chip FILL = layer), coloured exactly as the chips paint.
            ui.horizontal_wrapped(|ui| {
                for (kind, name) in [
                    (NodeKind::Component, "UI component"),
                    (NodeKind::Grpc, "gRPC"),
                    (NodeKind::Cli, "CLI command"),
                    (NodeKind::CoreFn, "core fn"),
                    (NodeKind::Table, "warehouse table"),
                ] {
                    let (fill, _stroke) = kind_color(&theme, kind);
                    let (rect, _) = ui.allocate_exact_size(Vec2::new(12.0, 12.0), Sense::hover());
                    ui.painter().rect_filled(rect, 2.0, fill);
                    ui.label(name);
                    ui.add_space(8.0);
                }
            });
            // The coverage legend + summary (chip RING = test-matrix cross-check):
            // does a test exist for this marker? This is the keystone of the tab.
            let (tested, untested, allowlisted, unknown) = self.cov_counts();
            ui.horizontal_wrapped(|ui| {
                ui.label("tests:");
                for (col, name, n) in [
                    (super::facett_theme::GREEN, "tested", tested),
                    (super::facett_theme::RED, "untested", untested),
                    (super::facett_theme::AMBER, "allowlisted", allowlisted),
                ] {
                    let (rect, _) = ui.allocate_exact_size(Vec2::new(12.0, 12.0), Sense::hover());
                    ui.painter().rect_stroke(
                        rect,
                        2.0,
                        Stroke::new(2.0, col),
                        egui::epaint::StrokeKind::Outside,
                    );
                    ui.label(format!("{name} {n}"));
                    ui.add_space(8.0);
                }
                if unknown > 0 {
                    ui.label(format!("· {unknown} not in surface_coverage"));
                }
                if tested + untested + allowlisted + unknown == self.graph.nodes.len()
                    && self.coverage.is_empty()
                {
                    ui.label("· (no coverage recorded — run `nornir test coverage`)");
                }
            });
        });

        // Edge-triggered render trace (LAW #6): emit what the board shows once per
        // data/selection change, not every frame.
        if self.render_dirty {
            trace::emit_end("architecture.render", &self.render_out());
            self.render_dirty = false;
        }

        // Click-to-code: the inline source-preview panel (sits below the board,
        // above the central canvas — egui needs side/bottom panels declared
        // before the CentralPanel). Shows the lines around the last-clicked
        // symbol's `file:line`, the editor-open result, and any extra candidates.
        self.draw_source_preview(ui);

        egui::CentralPanel::default().show_inside(ui, |ui| {
            if let Some(err) = &self.load_error {
                ui.colored_label(super::facett_theme::RED, format!("architecture load failed: {err}"));
                return;
            }
            for e in &self.errors {
                ui.colored_label(super::facett_theme::AMBER, format!("⚠ {e}"));
            }
            if self.graph.nodes.is_empty() {
                self.draw_placeholder(ui);
                return;
            }

            let (resp, painter) = ui.allocate_painter(ui.available_size(), Sense::click_and_drag());
            painter.rect_filled(resp.rect, 4.0, theme.bg);
            if resp.dragged() {
                self.pan += resp.drag_delta();
            }
            if resp.hovered() {
                let scroll = ui.input(|i| i.raw_scroll_delta.y);
                if scroll != 0.0 {
                    self.zoom = (self.zoom * (1.0 + scroll * 0.001)).clamp(0.25, 4.0);
                }
            }
            let origin = resp.rect.center() + self.pan;
            let zoom = self.zoom;
            let project = |p: Pos2| origin + p.to_vec2() * zoom;

            // Click-to-select: nearest node within its box; clicking empty clears.
            if resp.clicked() {
                if let Some(click) = resp.interact_pointer_pos() {
                    let hit = self.laid.iter().enumerate().find_map(|(i, l)| {
                        let c = project(l.pos);
                        let half = Vec2::new(BOX_W, BOX_H) * 0.5 * zoom;
                        let rect = egui::Rect::from_center_size(c, half * 2.0);
                        rect.contains(click).then_some(i)
                    });
                    match hit {
                        Some(i) => {
                            self.selected = Some(i);
                            self.trace_from(i);
                            // Click-to-code: resolve the clicked node → file:line,
                            // open in the editor (best-effort) + load the inline
                            // source preview. Tables have no symbol; skip them.
                            let node = &self.laid[i].node;
                            if node.kind != NodeKind::Table {
                                let label = node.label.clone();
                                self.open_symbol(&label, true);
                            }
                        }
                        None => {
                            self.selected = None;
                            self.traced.clear();
                        }
                    }
                    self.render_dirty = true;
                }
            }

            let highlighting = self.selected.is_some();
            // Edges first (so chips sit on top).
            for e in &self.graph.edges {
                let (Some(&fi), Some(&ti)) = (self.idx.get(&e.from), self.idx.get(&e.to)) else {
                    continue;
                };
                let on_trace =
                    highlighting && self.traced.contains(&fi) && self.traced.contains(&ti);
                let (pa, pb) = (project(self.laid[fi].pos), project(self.laid[ti].pos));
                // Start at the source chip's right edge, end at the target's left.
                let a = pa + Vec2::new(BOX_W * 0.5 * zoom, 0.0);
                let b = pb - Vec2::new(BOX_W * 0.5 * zoom, 0.0);
                let base = edge_color(&theme, e.kind);
                let color = if highlighting && !on_trace {
                    dim(base)
                } else {
                    base
                };
                let w = if on_trace { 2.4 } else { 1.4 };
                // PCB-ish cubic with a mid breakpoint.
                let mid = Pos2::new((a.x + b.x) * 0.5, a.y);
                let mid2 = Pos2::new((a.x + b.x) * 0.5, b.y);
                painter.add(egui::Shape::CubicBezier(egui::epaint::CubicBezierShape::from_points_stroke(
                    [a, mid, mid2, b],
                    false,
                    Color32::TRANSPARENT,
                    Stroke::new(w, color),
                )));
                // Arrowhead at the callee.
                let dir = (b - mid2).normalized();
                let perp = Vec2::new(-dir.y, dir.x);
                let head = 6.0 * zoom.clamp(0.6, 1.6);
                painter.line_segment([b, b - dir * head + perp * head * 0.5], Stroke::new(w, color));
                painter.line_segment([b, b - dir * head - perp * head * 0.5], Stroke::new(w, color));
            }

            // Chips (nodes).
            for (i, l) in self.laid.iter().enumerate() {
                let c = project(l.pos);
                let (fill, stroke) = kind_color(&theme, l.node.kind);
                let on_trace = highlighting && self.traced.contains(&i);
                let (fill, stroke) = if highlighting && !on_trace {
                    (dim(fill), dim(stroke))
                } else {
                    (fill, stroke)
                };
                let size = Vec2::new(BOX_W, BOX_H) * zoom;
                let rect = egui::Rect::from_center_size(c, size);
                painter.rect_filled(rect, 5.0 * zoom, fill);
                // Ring = the test-matrix cross-check: green tested / red untested /
                // amber allowlisted; falls back to the kind stroke when unknown.
                // The selection ring still wins when this node is clicked.
                let ring = if self.selected == Some(i) {
                    Stroke::new(3.0, theme.selection())
                } else if let Some(cv) = cov_ring(self.cov_of(&l.node.id)) {
                    let cv = if highlighting && !on_trace { dim(cv) } else { cv };
                    Stroke::new(2.2, cv)
                } else {
                    Stroke::new(1.4, stroke)
                };
                painter.rect_stroke(rect, 5.0 * zoom, ring, egui::epaint::StrokeKind::Outside);
                if zoom > 0.45 {
                    painter.text(
                        c,
                        egui::Align2::CENTER_CENTER,
                        &l.node.label,
                        FontId::proportional(11.0 * zoom.clamp(0.7, 1.4)),
                        theme.text,
                    );
                }
            }

            // Hint footer.
            let hint = match self.selected {
                Some(i) => format!(
                    "{} — {} downstream node(s) lit · click empty to clear · drag to pan, scroll to zoom",
                    self.laid[i].node.label,
                    self.traced.len().saturating_sub(1),
                ),
                None => "click a node to highlight its downstream wiring · drag to pan, scroll to zoom".to_string(),
            };
            painter.text(
                resp.rect.left_top() + Vec2::new(8.0, 8.0),
                egui::Align2::LEFT_TOP,
                hint,
                FontId::proportional(12.0),
                theme.text_dim,
            );
        });

        // Live system: keep repainting so a warehouse change animates in.
        if self.sub == ArchSubView::Live && self.live {
            ui.ctx().request_repaint_after(Duration::from_millis(600));
        }
    }

    /// The inline source-preview panel for the last click-to-code resolution: the
    /// resolved `file:line`, the editor-open status, the source window, and any
    /// extra candidates. Hidden when nothing has been clicked. (ii) of the
    /// click-to-code contract.
    fn draw_source_preview(&mut self, ui: &mut egui::Ui) {
        let Some(open) = self.last_open.clone() else { return };
        let theme = self.theme;
        egui::TopBottomPanel::bottom("arch_source_preview")
            .resizable(true)
            .default_height(180.0)
            .show_inside(ui, |ui| {
                ui.horizontal(|ui| {
                    ui.label(RichText::new("📄 source").strong().color(theme.accent));
                    ui.label(RichText::new(&open.query).monospace().color(theme.text));
                    if let Some(best) = open.hits.first() {
                        ui.label(
                            RichText::new(format!("→ {}:{}", best.file, best.line))
                                .monospace()
                                .color(theme.text_dim),
                        );
                        match open.editor_opened {
                            Some(true) => { ui.colored_label(super::facett_theme::GREEN, "✓ opened in editor"); }
                            Some(false) => { ui.colored_label(super::facett_theme::AMBER, "code not found (preview only)"); }
                            None => {}
                        }
                    } else {
                        ui.colored_label(super::facett_theme::AMBER, "no symbol matched");
                    }
                    if ui.button("✖").on_hover_text("close preview").clicked() {
                        self.last_open = None;
                    }
                });
                if open.preview.is_empty() {
                    if !open.hits.is_empty() {
                        ui.weak("(source file not in this checkout — run locally to preview lines)");
                    }
                    return;
                }
                ui.separator();
                ScrollArea::vertical().id_salt("arch_src").auto_shrink([false, false]).show(ui, |ui| {
                    let target = open.hits.first().map(|h| h.line).unwrap_or(0);
                    for (off, line) in open.preview.iter().enumerate() {
                        let n = open.preview_start + off as u32;
                        let is_target = n == target;
                        let num = RichText::new(format!("{n:>5} ")).monospace().color(theme.text_dim);
                        let src = RichText::new(line).monospace().color(if is_target {
                            theme.accent
                        } else {
                            theme.text
                        });
                        ui.horizontal(|ui| {
                            ui.label(num);
                            if is_target {
                                ui.label(RichText::new("▶").color(theme.accent));
                            }
                            ui.label(src);
                        });
                    }
                });
            });
    }

    /// The 📍 **Hållpunkter** (boundaries) lens: the ui / gRPC / emitter LANDMARK
    /// functions drawn as distinct landmark nodes (chips), grouped by boundary,
    /// classified with the coverage feature's [`crate::coverage::classify`]
    /// (REUSED). Each landmark is clickable → click-to-code (same as the board).
    fn draw_boundaries(&mut self, ui: &mut egui::Ui) {
        let theme = self.theme;
        self.ensure_symbols();
        let landmarks = self.boundary_landmarks();
        let (u, g, e) = self.boundary_tally();

        egui::TopBottomPanel::top("arch_boundaries_head").show_inside(ui, |ui| {
            ui.horizontal_wrapped(|ui| {
                ui.heading("📍 Hållpunkter");
                ui.separator();
                ui.label("the hard-to-cover layer boundaries — the anchors a test matrix must reach");
            });
            ui.horizontal_wrapped(|ui| {
                ui.colored_label(theme.accent, format!("ui {u}"));
                ui.add_space(8.0);
                ui.colored_label(super::facett_theme::AMBER, format!("gRPC {g}"));
                ui.add_space(8.0);
                ui.colored_label(theme.point, format!("emitter {e}"));
                if self.repo_root.as_os_str().is_empty() {
                    ui.separator();
                    ui.weak("(remote: no checkout — run locally to classify landmarks)");
                }
            });
        });

        // The click-to-code preview panel works here too.
        self.draw_source_preview(ui);

        egui::CentralPanel::default().show_inside(ui, |ui| {
            if landmarks.is_empty() {
                ui.add_space(12.0);
                ui.weak(
                    "no boundary landmarks discovered yet — they are classified from the \
                     repo's scanned symbols (ui/draw/state_json under src/viz, gRPC handlers, \
                     emit*/trace points).",
                );
                return;
            }
            let mut to_open: Option<String> = None;
            ScrollArea::vertical().id_salt("arch_landmarks").auto_shrink([false, false]).show(ui, |ui| {
                for (bnd, group_color, group_name) in [
                    (Boundary::Ui, theme.accent, "ui (impl Facet)"),
                    (Boundary::Grpc, super::facett_theme::AMBER, "gRPC handlers"),
                    (Boundary::Emitter, theme.point, "emitter (state_json / emit* / $NORNIR_VIZ_TRACE)"),
                ] {
                    let group: Vec<&ArchNode> =
                        landmarks.iter().filter(|(b, _)| *b == bnd).map(|(_, n)| n).collect();
                    if group.is_empty() {
                        continue;
                    }
                    ui.add_space(6.0);
                    ui.label(RichText::new(group_name).strong().color(group_color));
                    ui.horizontal_wrapped(|ui| {
                        for n in group {
                            let chip = egui::Button::new(
                                RichText::new(&n.label).monospace().size(11.0).color(theme.text),
                            )
                            .fill(group_color.linear_multiply(0.22))
                            .stroke(Stroke::new(1.2, group_color));
                            if ui.add(chip).on_hover_text("open source (click-to-code)").clicked() {
                                to_open = Some(n.label.clone());
                            }
                        }
                    });
                }
            });
            if let Some(label) = to_open {
                self.open_symbol(&label, true);
            }
        });
    }

    /// The clean "nothing generated yet" placeholder — never a hard error.
    fn draw_placeholder(&self, ui: &mut egui::Ui) {
        ui.add_space(24.0);
        ui.vertical_centered(|ui| {
            ui.heading("No architecture wiring recorded yet");
            ui.add_space(8.0);
            ui.label(
                "The EPIC ARCH board is generated per repo and historized in the \
                 warehouse. Generate it, then reload this tab:",
            );
            ui.add_space(6.0);
            let cmd = if self.members.is_empty() {
                "nornir arch generate --repo <member>".to_string()
            } else {
                format!("nornir arch generate --repo {}", self.members[0])
            };
            ui.code(&cmd);
            if !self.members.is_empty() {
                ui.add_space(8.0);
                ui.label(format!(
                    "members in this workspace with no board yet: {}",
                    self.members
                        .iter()
                        .filter(|m| !self.members_with_data.contains(m))
                        .cloned()
                        .collect::<Vec<_>>()
                        .join(", ")
                ));
            }
        });
    }

    /// Per-marker test-matrix tally: (tested, untested, allowlisted, unknown).
    /// The keystone numbers — green ⟺ every marker has a covering test.
    fn cov_counts(&self) -> (usize, usize, usize, usize) {
        let (mut t, mut u, mut a, mut k) = (0, 0, 0, 0);
        for n in &self.graph.nodes {
            match self.cov_of(&n.id) {
                Cov::Tested => t += 1,
                Cov::Untested => u += 1,
                Cov::Allowlisted => a += 1,
                Cov::Unknown => k += 1,
            }
        }
        (t, u, a, k)
    }

    fn render_out(&self) -> RenderOut {
        let count = |k: NodeKind| self.graph.nodes.iter().filter(|n| n.kind == k).count();
        let (tested, untested, allowlisted, coverage_unknown) = self.cov_counts();
        RenderOut {
            node_count: self.graph.nodes.len(),
            edge_count: self.graph.edges.len(),
            components: count(NodeKind::Component),
            grpc: count(NodeKind::Grpc),
            cli: count(NodeKind::Cli),
            core_fns: count(NodeKind::CoreFn),
            tables: count(NodeKind::Table),
            tested,
            untested,
            allowlisted,
            coverage_unknown,
            selected: self.selected.map(|i| self.laid[i].node.label.clone()),
        }
    }

    /// The 🏛 Architecture tab's slice of `state_json` (LAW #6) — the exact board
    /// it renders: counts per kind, edges, which members contributed, the selected
    /// node + its downstream-traced labels, and the active palette.
    pub fn state_json(&self) -> serde_json::Value {
        let count = |k: NodeKind| self.graph.nodes.iter().filter(|n| n.kind == k).count();
        let kinds: Vec<serde_json::Value> = self
            .graph
            .nodes
            .iter()
            .map(|n| {
                serde_json::json!({
                    "id": n.id,
                    "label": n.label,
                    "kind": n.kind.as_str(),
                    // The canonical layer (ui/grpc/cli/core/table) — AUT8-GAP-LAYER,
                    // derived from kind so the matrix groups by the same strata.
                    "layer": n.kind.layer(),
                    // The per-marker cross-check: is there a test for it?
                    "cov": self.cov_of(&n.id).label(),
                })
            })
            .collect();
        let (tested, untested, allowlisted, coverage_unknown) = self.cov_counts();
        let edges: Vec<serde_json::Value> = self
            .graph
            .edges
            .iter()
            .map(|e| serde_json::json!({ "from": e.from, "to": e.to, "kind": e.kind.as_str() }))
            .collect();
        let traced: Vec<String> =
            self.traced.iter().map(|&i| self.laid[i].node.label.clone()).collect();
        // 📍 Hållpunkter: the boundary landmark tally + the landmark labels by
        // boundary, classified with the coverage feature's `classify` (reused).
        let (bnd_ui, bnd_grpc, bnd_emitter) = self.boundary_tally();
        let landmark_list: Vec<serde_json::Value> = self
            .boundary_landmarks()
            .iter()
            .map(|(b, n)| serde_json::json!({ "boundary": b.as_str(), "label": n.label, "id": n.id }))
            .collect();
        serde_json::json!({
            "source": match &self.src { Src::Local(_) => "local", Src::Remote { .. } => "remote" },
            "workspace": self.workspace,
            "node_count": self.graph.nodes.len(),
            "edge_count": self.graph.edges.len(),
            "components": count(NodeKind::Component),
            "grpc": count(NodeKind::Grpc),
            "cli": count(NodeKind::Cli),
            "core_fns": count(NodeKind::CoreFn),
            "tables": count(NodeKind::Table),
            // The keystone cross-check, as readable data: every marker tallied
            // against the test matrix. green ⟺ untested == 0.
            "coverage": {
                "tested": tested,
                "untested": untested,
                "allowlisted": allowlisted,
                "unknown": coverage_unknown,
                "has_data": !self.coverage.is_empty(),
            },
            "nodes": kinds,
            "edges": edges,
            "members_with_data": self.members_with_data,
            "members": self.members,
            "errors": self.errors,
            "load_error": self.load_error,
            "selected": self.selected.map(|i| self.laid[i].node.label.clone()),
            "traced_downstream": traced,
            "empty": self.graph.nodes.is_empty(),
            "palette": self.theme.name,
            // ── CONTAINER: the active sub-view + the full sub-view list, so the
            // headless matrix mechanically enumerates every lens (LAW #6).
            "sub_view": self.sub.id(),
            "sub_views": ArchSubView::ALL.iter().map(|v| v.id()).collect::<Vec<_>>(),
            "live": self.live,
            // ── 📍 Hållpunkter: the ui/grpc/emitter LANDMARK tally (the boundary
            // anchors), classified by the coverage feature's `classify` (reused).
            "boundaries": {
                "ui": bnd_ui,
                "grpc": bnd_grpc,
                "emitter": bnd_emitter,
                "total": bnd_ui + bnd_grpc + bnd_emitter,
                "landmarks": landmark_list,
            },
            // ── click-to-code: the last-clicked symbol → file:line + candidates,
            // the editor-open result, and the inline preview line range — so a
            // robot test asserts the click-to-code WITHOUT pixels (task #3).
            "last_open": self.last_open.as_ref().map(|o| serde_json::json!({
                "query": o.query,
                "resolved": o.hits.first().map(|h| format!("{}:{}", h.file, h.line)),
                "file": o.hits.first().map(|h| h.file.clone()),
                "line": o.hits.first().map(|h| h.line),
                "symbol": o.hits.first().map(|h| h.symbol.clone()),
                "candidates": o.hits.len(),
                "editor_opened": o.editor_opened,
                "preview_lines": o.preview.len(),
                "preview_start": o.preview_start,
            })),
        })
    }

    // ── test-only injectors (no warehouse / no server) ───────────────────────

    /// Inject a merged board directly (as the warehouse merge / RPC would deliver)
    /// + the configured members, so the inject-assert harness can read
    /// `state_json()` back without a warehouse or server. Returns nothing; after
    /// this the board renders the injected graph.
    #[doc(hidden)]
    pub fn inject_for_test(&mut self, graph: ArchGraph, members_with_data: Vec<String>) {
        self.loaded = true;
        self.load_error = None;
        self.members_with_data = members_with_data;
        self.errors = Vec::new();
        self.set_graph(graph);
    }

    /// Inject coverage verdicts (node id → `covered`/`missing`/`allowlisted`) as
    /// the warehouse cross-check would deliver, so a test can assert the green/red
    /// tally via `state_json()` without a warehouse.
    #[doc(hidden)]
    pub fn inject_coverage_for_test(
        &mut self,
        coverage: std::collections::BTreeMap<String, String>,
    ) {
        self.coverage = coverage;
        self.render_dirty = true;
    }

    /// Inject scanned symbols directly (no warehouse / no checkout) so a test can
    /// drive click-to-code resolution + the boundary-landmark classifier via
    /// `state_json()` / `open_symbol`. Mirrors the other inject seams.
    #[doc(hidden)]
    pub fn inject_symbols_for_test(&mut self, symbols: Vec<crate::knowledge::symbols::SymbolRow>) {
        self.symbols = Some(symbols);
        self.render_dirty = true;
    }

    /// Set the active sub-view from a test (parity with a selector click).
    #[doc(hidden)]
    pub fn set_sub_view_by_id_for_test(&mut self, id: &str) -> bool {
        match ArchSubView::from_id(id) {
            Some(sv) => {
                self.set_sub_view(sv);
                true
            }
            None => false,
        }
    }

    /// Drive a click on the node with `label` (parity with a pointer click), so a
    /// test can assert the downstream-trace highlight via `state_json()`.
    #[doc(hidden)]
    pub fn select_by_label_for_test(&mut self, label: &str) -> bool {
        if let Some(i) = self.laid.iter().position(|l| l.node.label == label) {
            self.selected = Some(i);
            self.trace_from(i);
            self.render_dirty = true;
            true
        } else {
            false
        }
    }
}

const BOX_W: f32 = 184.0;
const BOX_H: f32 = 34.0;

/// Chip (fill, stroke) per node kind, on the active facett palette. Each kind
/// gets a distinct semantic tint so the four layers read apart at a glance: UI
/// components on the palette accent, gRPC on amber, core-fns on the neutral
/// node-fill, warehouse tables on the palette point colour (the warehouse rail).
fn kind_color(theme: &Theme, kind: NodeKind) -> (Color32, Color32) {
    match kind {
        NodeKind::Component => (theme.accent.linear_multiply(0.30), theme.accent),
        NodeKind::Grpc => (
            super::facett_theme::AMBER.linear_multiply(0.30),
            super::facett_theme::AMBER,
        ),
        // CLI verbs on the palette edge colour — the third entrypoint marker
        // layer beside UI (accent) and gRPC (amber); kept off green/red so the
        // chip FILL never clashes with the coverage RING.
        NodeKind::Cli => (theme.edge.linear_multiply(0.30), theme.edge),
        NodeKind::CoreFn => (theme.node_fill, theme.node_stroke),
        NodeKind::Table => (theme.point.linear_multiply(0.30), theme.point),
    }
}

/// Edge colour per relation kind: calls on the palette accent, reads/writes on
/// amber (the warehouse access traces).
fn edge_color(theme: &Theme, kind: ArchEdgeKind) -> Color32 {
    match kind {
        ArchEdgeKind::Calls => theme.edge,
        ArchEdgeKind::Reads | ArchEdgeKind::Writes => super::facett_theme::AMBER,
    }
}

/// Dim a colour toward transparency for the un-traced background when a node is
/// selected (so the lit downstream path pops).
fn dim(c: Color32) -> Color32 {
    c.linear_multiply(0.22)
}

/// The coverage ring colour for a marker's test-matrix status: green = a test
/// exists, red = none, amber = allowlisted gap, `None` = unknown (keep the kind
/// stroke). Uses the facett status palette — no ad-hoc chrome.
fn cov_ring(cov: Cov) -> Option<Color32> {
    match cov {
        Cov::Tested => Some(super::facett_theme::GREEN),
        Cov::Untested => Some(super::facett_theme::RED),
        Cov::Allowlisted => Some(super::facett_theme::AMBER),
        Cov::Unknown => None,
    }
}

/// Layered BFS columns (verbatim model of `arch::layers_of`, reimplemented here
/// against the laid graph so the native render columns match the SVG's): layer 0
/// = sources (no incoming edge), tables pinned to the rightmost column (the
/// warehouse ground rail). Deterministic, cycle-safe.
fn layers_of(graph: &ArchGraph) -> Vec<Vec<usize>> {
    let n = graph.nodes.len();
    let idx: HashMap<&str, usize> =
        graph.nodes.iter().enumerate().map(|(i, nd)| (nd.id.as_str(), i)).collect();
    let mut adj: Vec<Vec<usize>> = vec![Vec::new(); n];
    let mut indeg: Vec<usize> = vec![0; n];
    for e in &graph.edges {
        if let (Some(&f), Some(&t)) = (idx.get(e.from.as_str()), idx.get(e.to.as_str())) {
            if f != t {
                adj[f].push(t);
                indeg[t] += 1;
            }
        }
    }
    let mut layer_of = vec![0usize; n];
    let mut remaining: BTreeSet<usize> = (0..n).collect();
    let mut level = 0usize;
    while !remaining.is_empty() {
        let ready: Vec<usize> = remaining.iter().copied().filter(|&i| indeg[i] == 0).collect();
        if ready.is_empty() {
            for &i in &remaining {
                layer_of[i] = level;
            }
            break;
        }
        for &i in &ready {
            layer_of[i] = level;
            remaining.remove(&i);
        }
        for &i in &ready {
            for &j in &adj[i] {
                if indeg[j] > 0 {
                    indeg[j] -= 1;
                }
            }
        }
        level += 1;
    }
    // Pin tables to the rightmost column (the warehouse ground rail).
    let mut max_level = *layer_of.iter().max().unwrap_or(&0);
    let has_table = graph.nodes.iter().any(|nd| nd.kind == NodeKind::Table);
    if has_table {
        max_level = max_level.max(1);
        for (i, nd) in graph.nodes.iter().enumerate() {
            if nd.kind == NodeKind::Table {
                layer_of[i] = max_level;
            }
        }
    }
    let mut layers: Vec<Vec<usize>> = vec![Vec::new(); max_level + 1];
    let mut order: Vec<usize> = (0..n).collect();
    order.sort_by(|&a, &b| graph.nodes[a].label.cmp(&graph.nodes[b].label));
    for i in order {
        layers[layer_of[i]].push(i);
    }
    layers
}

#[cfg(test)]
mod tests {
    use super::*;

    fn board() -> ArchGraph {
        // TestTab -reads-> test_results ; Viz.Architecture -writes-> release_lineage
        // ; TestTab -calls-> nornir::viz (a core fn).
        ArchGraph {
            nodes: vec![
                ArchNode { id: "component:TestTab".into(), label: "TestTab".into(), kind: NodeKind::Component },
                ArchNode { id: "grpc:Viz.Architecture".into(), label: "Viz.Architecture".into(), kind: NodeKind::Grpc },
                ArchNode { id: "corefn:nornir::viz".into(), label: "nornir::viz".into(), kind: NodeKind::CoreFn },
                ArchNode { id: "table:test_results".into(), label: "test_results".into(), kind: NodeKind::Table },
                ArchNode { id: "table:release_lineage".into(), label: "release_lineage".into(), kind: NodeKind::Table },
            ],
            edges: vec![
                ArchEdge { from: "component:TestTab".into(), to: "table:test_results".into(), kind: ArchEdgeKind::Reads },
                ArchEdge { from: "component:TestTab".into(), to: "corefn:nornir::viz".into(), kind: ArchEdgeKind::Calls },
                ArchEdge { from: "grpc:Viz.Architecture".into(), to: "table:release_lineage".into(), kind: ArchEdgeKind::Writes },
            ],
        }
    }

    #[test]
    fn injected_board_renders_counts_in_state_json() {
        let mut st = ArchTabState::local(PathBuf::from("/nonexistent"));
        st.set_members(vec!["nornir".into()]);
        st.inject_for_test(board(), vec!["nornir".into()]);
        let js = st.state_json();
        assert_eq!(js["node_count"], 5);
        assert_eq!(js["edge_count"], 3);
        assert_eq!(js["components"], 1);
        assert_eq!(js["grpc"], 1);
        assert_eq!(js["core_fns"], 1);
        assert_eq!(js["tables"], 2);
        assert_eq!(js["empty"], false);
        assert_eq!(js["members_with_data"][0], "nornir");
        assert_eq!(js["source"], "local");
    }

    #[test]
    fn empty_board_shows_placeholder_not_error() {
        let mut st = ArchTabState::local(PathBuf::from("/nonexistent"));
        st.set_members(vec!["nornir".into()]);
        st.inject_for_test(ArchGraph::default(), vec![]);
        let js = st.state_json();
        assert_eq!(js["empty"], true);
        assert_eq!(js["node_count"], 0);
        assert!(js["load_error"].is_null(), "empty board is not an error");
    }

    #[test]
    fn click_lights_downstream_trace() {
        let mut st = ArchTabState::local(PathBuf::from("/nonexistent"));
        st.inject_for_test(board(), vec!["nornir".into()]);
        // Click TestTab: downstream = {TestTab, test_results, nornir::viz}.
        assert!(st.select_by_label_for_test("TestTab"));
        let js = st.state_json();
        assert_eq!(js["selected"], "TestTab");
        let traced: BTreeSet<String> = js["traced_downstream"]
            .as_array()
            .unwrap()
            .iter()
            .map(|v| v.as_str().unwrap().to_string())
            .collect();
        assert!(traced.contains("TestTab"));
        assert!(traced.contains("test_results"));
        assert!(traced.contains("nornir::viz"));
        // release_lineage is NOT reachable from TestTab (it's Viz.Architecture's).
        assert!(!traced.contains("release_lineage"), "unreachable node not lit: {traced:?}");
    }

    #[test]
    fn layers_pin_tables_right_and_sources_left() {
        let g = board();
        let layers = layers_of(&g);
        // Sources (TestTab, Viz.Architecture — no incoming edge) in layer 0.
        let l0: BTreeSet<&str> =
            layers[0].iter().map(|&i| g.nodes[i].label.as_str()).collect();
        assert!(l0.contains("TestTab"));
        assert!(l0.contains("Viz.Architecture"));
        // Every table is pinned to the LAST layer (the warehouse ground rail), and
        // no table appears in any earlier column.
        let last = layers.len() - 1;
        for (li, layer) in layers.iter().enumerate() {
            for &i in layer {
                if g.nodes[i].kind == NodeKind::Table {
                    assert_eq!(li, last, "table `{}` not on the right rail", g.nodes[i].label);
                }
            }
        }
        // The last layer actually carries the tables.
        assert!(
            layers[last].iter().any(|&i| g.nodes[i].kind == NodeKind::Table),
            "the rightmost column carries the warehouse tables"
        );
    }

    #[test]
    fn coverage_cross_check_tallies_tested_vs_untested() {
        let mut st = ArchTabState::local(PathBuf::from("/nonexistent"));
        st.inject_for_test(board(), vec!["nornir".into()]);
        // TestTab has a test; Viz.Architecture has none; test_results is allowlisted.
        let mut cov = std::collections::BTreeMap::new();
        cov.insert("component:TestTab".to_string(), "covered".to_string());
        cov.insert("grpc:Viz.Architecture".to_string(), "missing".to_string());
        cov.insert("table:test_results".to_string(), "allowlisted".to_string());
        st.inject_coverage_for_test(cov);
        let js = st.state_json();
        // The keystone tally: green ⟺ untested == 0.
        assert_eq!(js["coverage"]["tested"], 1);
        assert_eq!(js["coverage"]["untested"], 1);
        assert_eq!(js["coverage"]["allowlisted"], 1);
        // 5 nodes, 3 carry a verdict → 2 unmatched (never a false green).
        assert_eq!(js["coverage"]["unknown"], 2);
        assert_eq!(js["coverage"]["has_data"], true);
        // The per-marker verdict surfaces in the nodes array.
        let nodes = js["nodes"].as_array().unwrap();
        let find = |id: &str| {
            nodes.iter().find(|n| n["id"] == id).unwrap()["cov"].as_str().unwrap().to_string()
        };
        assert_eq!(find("component:TestTab"), "tested");
        assert_eq!(find("grpc:Viz.Architecture"), "untested");
        assert_eq!(find("table:test_results"), "allowlisted");
        assert_eq!(find("corefn:nornir::viz"), "unknown");
    }

    #[test]
    fn no_coverage_data_is_all_unknown_not_false_green() {
        let mut st = ArchTabState::local(PathBuf::from("/nonexistent"));
        st.inject_for_test(board(), vec!["nornir".into()]);
        let js = st.state_json();
        assert_eq!(js["coverage"]["has_data"], false);
        assert_eq!(js["coverage"]["tested"], 0);
        assert_eq!(js["coverage"]["unknown"], 5, "no data → all unknown, none green");
    }

    #[test]
    fn palette_switch_reaches_pane() {
        let mut st = ArchTabState::local(PathBuf::from("/nonexistent"));
        st.inject_for_test(board(), vec!["nornir".into()]);
        assert_eq!(st.state_json()["palette"], "default");
        st.set_palette(Theme::cyberpunk_neon());
        assert_eq!(st.state_json()["palette"], "cyberpunk-neon");
    }
}