evolving 0.1.3

use crate::canonical::compute_id;
use crate::store::Store;
use crate::tick::{Check, Ground, Liveness, Tick};
use crate::verify::verify;
use std::path::Path;
use std::process::ExitCode;

/// Render an opaque `source_ref` for human display: a bare string verbatim, an object as its
/// deterministic compact JSON. ev only renders it — it never interprets the contents. Kept distinct
/// from `tick::source_ref_key` (which derives the dedup/join key): they coincide today but are
/// different concepts — display may later pretty-print, while the key must stay byte-stable.
fn render_source_ref(v: &serde_json::Value) -> String {
    v.as_str()
        .map(String::from)
        .unwrap_or_else(|| v.to_string())
}

/// Whether a triggering change landed after this ground's most recent run. Uses the latest
/// receipt's commit + the binding's triggered_by paths. False when there is no receipt, no
/// Test binding, or git can't tell (None ⇒ not evaluated).
fn triggered_since(
    repo: &std::path::Path,
    ground: &crate::tick::Ground,
    receipts: &[crate::receipt::Receipt],
) -> bool {
    use crate::tick::Check;
    let triggered_by = match &ground.check {
        Some(Check::Test { liveness, .. }) => &liveness.triggered_by,
        _ => return false,
    };
    let latest = receipts.iter().max_by(|a, b| a.ran_at.cmp(&b.ran_at));
    match latest {
        Some(r) => crate::liveness::changed_since(repo, &r.commit, triggered_by).unwrap_or(false),
        None => false,
    }
}

pub fn init(repo: &Path) -> ExitCode {
    let store = Store::at(repo);
    match store.init() {
        Ok(true) => {
            println!("created .evolving/  (content-addressed chain + results cache)");
            ExitCode::SUCCESS
        }
        Ok(false) => {
            println!(".evolving/ already exists (no-op)");
            ExitCode::SUCCESS
        }
        Err(e) => {
            eprintln!("error: could not create .evolving/: {e}");
            ExitCode::FAILURE
        }
    }
}
pub fn show(repo: &Path, id: &str) -> ExitCode {
    let store = Store::at(repo);
    let path = store.ticks_dir().join(id);
    if !path.is_file() {
        eprintln!("error: no tick with id {id}");
        return ExitCode::FAILURE;
    }
    match std::fs::read_to_string(&path) {
        Ok(text) => {
            // print as-is (the on-disk pretty JSON: hashed payload + bookkeeping).
            println!("{text}");
            // surface the declared authority on its own line when present (boot-time read).
            if let Ok(v) = serde_json::from_str::<serde_json::Value>(&text) {
                if let Some(a) = v.get("authority").and_then(|x| x.as_str()) {
                    println!("authority: {a}");
                }
                if let Some(j) = v.get("jurisdiction").and_then(|x| x.as_str()) {
                    println!("jurisdiction: {j}");
                }
                if let Some(r) = v.get("source_ref") {
                    println!("source_ref: {}", render_source_ref(r));
                }
            }
            ExitCode::SUCCESS
        }
        Err(e) => {
            eprintln!("error: reading {id}: {e}");
            ExitCode::FAILURE
        }
    }
}
pub fn decide(repo: &Path, decision: Option<&str>, args: &[String]) -> ExitCode {
    // clap fills the optional positional with the first token even when it is a flag (it carries
    // allow_hyphen_values so a leading --from-git can reach us at all). A real decision never
    // starts with '-', so a hyphen-leading "decision" is actually a flag: re-route it into args
    // and leave the positional empty, letting the capture flag-loop own --from-git uniformly.
    let (decision, args): (Option<&str>, Vec<String>) = match decision {
        Some(d) if d.starts_with('-') => {
            let mut v = vec![d.to_string()];
            v.extend_from_slice(args);
            (None, v)
        }
        other => (other, args.to_vec()),
    };
    match crate::capture::run(repo, decision, &args) {
        Ok(t) => {
            crate::events::append(&Store::at(repo), "decide", Some(&t.id), None);
            println!("recorded {} ({} ground(s))", t.id, t.grounds.len());
            ExitCode::SUCCESS
        }
        Err(e) => {
            eprintln!("error: {e}");
            ExitCode::FAILURE
        }
    }
}

pub fn guard(repo: &Path, a: crate::guard::GuardArgs) -> ExitCode {
    match crate::guard::run(repo, a) {
        Ok(t) => {
            crate::events::append(&Store::at(repo), "guard", Some(&t.id), None);
            println!("bound; wrote child {}", t.id);
            ExitCode::SUCCESS
        }
        Err(e) => {
            eprintln!("error: {e}");
            ExitCode::FAILURE
        }
    }
}

pub fn verify_cmd(repo: &Path, self_test: bool) -> ExitCode {
    if self_test {
        return self_test_golden();
    }
    let store = Store::at(repo);
    // Forward-compat: tolerated unknown top-level keys are warnings, never violations — they do
    // not affect the verdict, but they keep a typo'd field name visible.
    for w in crate::verify::unknown_key_warnings(&store).unwrap_or_default() {
        eprintln!("{w}");
    }
    // Provenance partition: an op-word in faithfully-transcribed imported history is a warning, not a
    // gating violation — surfaced here so it stays visible while fresh authorship keeps the op-lint hard.
    for w in crate::verify::imported_op_warnings(&store).unwrap_or_default() {
        eprintln!("{w}");
    }
    match verify(&store) {
        Ok(v) if v.is_empty() => {
            println!("✓ chain intact: every id == hash(payload), lineage forward-only");
            println!("✓ every tick validates against the closed schema (R1) and check shape (R2)");
            ExitCode::SUCCESS
        }
        Ok(v) => {
            for line in &v {
                println!("✗ {line}");
            }
            eprintln!("{} violation(s)", v.len());
            ExitCode::FAILURE
        }
        Err(e) => {
            eprintln!("error: reading store: {e}");
            ExitCode::FAILURE
        }
    }
}

/// The latest ran_at across a ref's receipts (for the display line), if any.
/// `receipts` is already scoped to one ref by `read_for`, so no filtering is needed.
fn latest_ran_at(receipts: &[crate::receipt::Receipt]) -> Option<String> {
    receipts.iter().map(|r| r.ran_at.clone()).max()
}

/// The evaluation context for one `ev check` / `ev reopen` invocation: the staleness reference
/// (resolved per policy by the caller), the selected-list, the wall clock, and the staleness
/// window. The I/O assembly lives here in the command layer so `verdict::verdict_for` stays pure.
fn live_ctx(
    store: &Store,
    staleness_days: u64,
    live_origin_sha: Option<String>,
    attest: Option<Vec<String>>,
) -> crate::verdict::Ctx {
    crate::verdict::Ctx {
        live_origin_sha,
        selected: crate::selected::read(store).unwrap_or(None),
        now_unix: time::OffsetDateTime::now_utc().unix_timestamp(),
        staleness_secs: staleness_days as i64 * 86_400,
        attest,
    }
}

pub fn check(
    repo: &Path,
    exit_on_red: bool,
    run: bool,
    platform: &str,
    offline: bool,
    attest: Vec<String>,
) -> ExitCode {
    use crate::verdict::{verdict_for, Verdict};
    let store = Store::at(repo);
    if !store.exists() {
        eprintln!("error: no .evolving/ store here — run `ev init` first");
        return ExitCode::FAILURE;
    }
    let files = match store.read_all() {
        Ok(f) => f,
        Err(e) => {
            eprintln!("error: reading store: {e}");
            return ExitCode::FAILURE;
        }
    };
    let config = crate::config::read(&store);

    // --run pass: for every live Test-bound ground that declares this platform, run the
    // bound ref locally and append a receipt for it (one local run = one platform receipt).
    if run {
        for (_filename, raw) in &files {
            let t = match crate::tick::from_value(raw) {
                Ok(t) => t,
                Err(_) => continue,
            };
            if t.status != "live" {
                continue;
            }
            for g in &t.grounds {
                if let Some(Check::Test {
                    reference,
                    counter_test,
                    liveness,
                    ..
                }) = &g.check
                {
                    if liveness.platforms.iter().any(|p| p == platform) {
                        // run the bound check
                        match crate::runner::run_check(
                            repo,
                            reference,
                            platform,
                            config.green_exit_code,
                        ) {
                            Ok(mut rc) => {
                                // prove falsifiability: the counter-test must produce the OPPOSITE
                                // result. A harvested binding (counter_test None) skips this step,
                                // leaving falsifiable None — the existing default.
                                if let Some(counter_test) = counter_test {
                                    if let Ok(ct) = crate::runner::run_check(
                                        repo,
                                        counter_test,
                                        platform,
                                        config.green_exit_code,
                                    ) {
                                        rc.falsifiable = Some(rc.result != ct.result);
                                    }
                                }
                                if let Err(e) = crate::receipt::append(&store, &rc) {
                                    eprintln!(
                                        "warning: could not write receipt for {reference:?}: {e}"
                                    );
                                }
                            }
                            Err(e) => eprintln!("warning: run failed for {reference:?}: {e}"),
                        }
                    }
                }
            }
        }
    }

    let live_origin = crate::staleness::resolve(repo, &store, &config.staleness_ref, offline);
    let attest = if attest.is_empty() {
        None
    } else {
        Some(attest)
    };
    let ctx = live_ctx(&store, config.staleness_days, live_origin, attest);
    let mut rows: Vec<String> = Vec::new();
    let mut any_not_green = false;
    // Harvested-binding honesty debt: N test bindings carry no counter-test (counter_test None) out
    // of M total test bindings. Surfaced as a trailing line so the missing falsifiability proof is
    // never silent — the verdict itself stays honest (a harvested green/red reads exactly as it ran).
    let mut total_test_bindings = 0usize;
    let mut harvested_unproven = 0usize;

    for (filename, raw) in &files {
        let t = match crate::tick::from_value(raw) {
            Ok(t) => t,
            Err(_) => continue, // ev verify owns schema errors; check skips unparsable ticks
        };
        if t.status != "live" {
            continue;
        }
        let mut verdicts = Vec::with_capacity(t.grounds.len());
        for g in &t.grounds {
            // Receipts are read only for Test-bound grounds; person/unbound need none.
            let receipts = match &g.check {
                Some(Check::Test { reference, .. }) => {
                    crate::receipt::read_for(&store, reference).unwrap_or_default()
                }
                _ => Vec::new(),
            };
            // verdict_for returns NotApplicable for any non-Test ground.
            let ts = triggered_since(repo, g, &receipts);
            let mut v = verdict_for(g, &receipts, &ctx, ts);
            // LOCK 1 (gate-time, structural): a C/D-jurisdiction (detect-only) decision is
            // structurally ungateable — map ANY not-green verdict to the non-gating Memo BEFORE the
            // any_not_green writer below, so it can never flip --exit-on-red. Remapping every
            // not-green at once is more robust than threading Memo through each gate site.
            if matches!(t.jurisdiction.as_deref(), Some("C") | Some("D"))
                && !matches!(v, Verdict::Green | Verdict::NotApplicable | Verdict::Exempt)
            {
                v = Verdict::Memo;
            }
            if !matches!(
                v,
                Verdict::Green | Verdict::NotApplicable | Verdict::Exempt | Verdict::Memo
            ) {
                any_not_green = true;
            }
            // Only Test-bound grounds appear in the printed set and the gate.
            if let Some(Check::Test { counter_test, .. }) = &g.check {
                total_test_bindings += 1;
                let harvested = counter_test.is_none();
                let mut detail = match &v {
                    Verdict::NotRun { missing_platforms } => {
                        format!("missing: {}", missing_platforms.join(", "))
                    }
                    Verdict::Stale { reason } => reason.clone(),
                    _ => latest_ran_at(&receipts)
                        .map(|ts| format!("ran {ts}"))
                        .unwrap_or_else(|| "no receipt".into()),
                };
                // A harvested binding carries no counter-test, so its falsifiability was never
                // proven; annotate the row honestly. The verdict is UNCHANGED — a passing harvested
                // test still reads green (pass-green), a failing one still reads red (a real gate).
                if harvested {
                    harvested_unproven += 1;
                    detail = format!("harvested — falsifiability not proven; {detail}");
                    crate::events::append(&store, "harvested", Some(&t.id), Some(v.label()));
                }
                rows.push(format!(
                    "{}\t{filename}\t{:?}\t({detail})",
                    v.label(),
                    g.claim
                ));
                crate::events::append(&store, "check", Some(&t.id), Some(v.label()));
            }
            verdicts.push((g, v));
        }
        // The per-host verdict-cache read contract for this tick (a hook reads it without shelling check).
        let _ = crate::state::write_state(
            &store,
            &t.id,
            &verdicts,
            &config.staleness_ref,
            ctx.live_origin_sha.as_deref(),
        );
    }

    if rows.is_empty() {
        println!("no test-bound grounds to check");
    } else {
        for r in &rows {
            println!("{r}");
        }
        // The harvested-binding debt: how many of the test bindings have no counter-test (so their
        // falsifiability is unproven). Pointed at `ev guard`, which is how a counter-test is added.
        if harvested_unproven > 0 {
            println!(
                "harvested-unproven: {harvested_unproven} of {total_test_bindings} test bindings have no counter-test (run ev guard to add one)"
            );
        }
        if !run {
            // under --run the verdict itself carries falsifiability (an `unproven` row is a
            // counter-test that did not flip); without it, point at the proof step rather than
            // implying one already happened.
            println!("note: run `ev check --run` to execute each counter-test and prove its falsifiability");
        }
    }
    if exit_on_red && any_not_green {
        return ExitCode::FAILURE;
    }
    ExitCode::SUCCESS
}

/// The parsed `ev migrate` invocation (built in main.rs from the clap subcommand).
pub struct MigrateArgs {
    pub sources: Vec<String>,
    pub dry_run: bool,
    pub reconcile: bool,
    pub against: Option<String>,
    pub blame: Option<String>,
    pub bind_check: Option<String>,
    pub platforms: Vec<String>,
    pub triggered_by: Vec<String>,
    pub surfaces: Vec<String>,
    pub verified_at_sha: Option<String>,
    pub jurisdiction_map: Option<String>,
}

/// Read a `--jurisdiction-map` file into a `source_key -> bucket` map. Each non-blank, non-`#` line is
/// exactly two whitespace-separated tokens `<source_key> <bucket>`; every bucket is validated against
/// the closed A/B/C/D vocabulary so an out-of-vocab bucket (or a malformed line) is a hard error that
/// names the offending line. jurisdiction is non-hashed, so the map only adds a detect-only tag — it
/// never moves a tick id. An absent path yields an empty map (every record imports untagged).
fn parse_jurisdiction_map(path: &str) -> Result<std::collections::HashMap<String, String>, String> {
    let text = std::fs::read_to_string(path).map_err(|e| format!("reading {path}: {e}"))?;
    let mut map = std::collections::HashMap::new();
    for line in text.lines() {
        let l = line.trim();
        if l.is_empty() || l.starts_with('#') {
            continue;
        }
        let mut tokens = l.split_whitespace();
        match (tokens.next(), tokens.next(), tokens.next()) {
            (Some(key), Some(bucket), None) => {
                crate::tick::validate_jurisdiction(bucket)
                    .map_err(|e| format!("jurisdiction-map line {l:?}: {e}"))?;
                map.insert(key.to_string(), bucket.to_string());
            }
            _ => {
                return Err(format!(
                    "jurisdiction-map line {l:?}: expected `<source_key> <bucket>`"
                ))
            }
        }
    }
    Ok(map)
}

/// Read a `<kind>:<path>` source spec, dispatch to the matching pure extractor, and return the
/// extracted records. The kind names the substrate format; the path is read from disk here (the
/// extractors themselves stay pure `&str -> Vec<MigrationRecord>`).
fn extract_source(spec: &str) -> Result<Vec<crate::migrate::MigrationRecord>, String> {
    let (kind, path) = spec
        .split_once(':')
        .ok_or_else(|| format!("--source expects <kind>:<path>, got {spec:?}"))?;
    let text = std::fs::read_to_string(path).map_err(|e| format!("reading {path}: {e}"))?;
    let recs = match kind {
        // The format-neutral primary intake: a producer-owned adapter (or a live runner) emits the
        // Canonical Decision Intake JSONL, re-validated through ev's read-path validators on the way in.
        "canonical" => crate::migrate::canonical_records(&text)?,
        "gitlog" => crate::migrate::extract_gitlog(&text),
        "to-human" => crate::migrate::extract_to_human(&text),
        "decisions-immutable" => crate::migrate::extract_decisions_immutable(&text),
        "escalation" => crate::migrate::extract_escalation(&text),
        other => {
            return Err(format!(
                "unknown source kind {other:?} (expected canonical | gitlog | to-human | decisions-immutable | escalation)"
            ))
        }
    };
    Ok(recs)
}

pub fn migrate(repo: &Path, a: MigrateArgs) -> ExitCode {
    // --bind-check: harvest one existing test as a (counter-test-less) bound check and print it.
    if let Some(selector) = &a.bind_check {
        let sha = match crate::capture::resolve_sha(repo, &a.verified_at_sha) {
            Ok(s) => s,
            Err(e) => {
                eprintln!("error: {e}");
                return ExitCode::FAILURE;
            }
        };
        match crate::migrate::bind_check(
            selector.clone(),
            sha,
            a.platforms.clone(),
            a.triggered_by.clone(),
            a.surfaces.clone(),
        ) {
            Ok(Check::Test {
                reference,
                liveness,
                ..
            }) => {
                println!(
                    "harvested check (falsifiability not proven; no counter-test): {reference:?} on [{}] triggered-by [{}] surface [{}]",
                    liveness.platforms.join(", "),
                    liveness.triggered_by.join(", "),
                    liveness.surfaces.join(", ")
                );
                return ExitCode::SUCCESS;
            }
            Ok(_) => unreachable!("bind_check yields a Test check"),
            Err(e) => {
                eprintln!("error: {e}");
                return ExitCode::FAILURE;
            }
        }
    }

    // --reconcile --against <src>: join the source against the store and report the buckets.
    if a.reconcile {
        let against = match &a.against {
            Some(s) => s,
            None => {
                eprintln!("error: --reconcile requires --against <kind>:<path>");
                return ExitCode::FAILURE;
            }
        };
        let recs = match extract_source(against) {
            Ok(r) => r,
            Err(e) => {
                eprintln!("error: {e}");
                return ExitCode::FAILURE;
            }
        };
        match crate::migrate::reconcile(repo, &recs) {
            Ok(rep) => {
                println!(
                    "reconcile: in-both {}, source-only {} (the capture gap), store-only {}, un-keyable {}",
                    rep.in_both, rep.source_only, rep.store_only, rep.un_keyable
                );
                return ExitCode::SUCCESS;
            }
            Err(e) => {
                eprintln!("error: {e}");
                return ExitCode::FAILURE;
            }
        }
    }

    // The default action: backfill every --source into the ledger (idempotent).
    if a.sources.is_empty() {
        eprintln!("error: ev migrate needs at least one --source <kind>:<path> (or --reconcile / --bind-check)");
        return ExitCode::FAILURE;
    }
    let mut records = Vec::new();
    for spec in &a.sources {
        match extract_source(spec) {
            Ok(mut r) => records.append(&mut r),
            Err(e) => {
                eprintln!("error: {e}");
                return ExitCode::FAILURE;
            }
        }
    }
    // An omitted --jurisdiction-map ⇒ an empty map ⇒ every record imports untagged (prior behavior).
    let jurisdiction_map = match &a.jurisdiction_map {
        Some(path) => match parse_jurisdiction_map(path) {
            Ok(m) => m,
            Err(e) => {
                eprintln!("error: {e}");
                return ExitCode::FAILURE;
            }
        },
        None => std::collections::HashMap::new(),
    };
    match crate::migrate::backfill(
        repo,
        records,
        a.blame.as_deref(),
        &jurisdiction_map,
        a.dry_run,
    ) {
        Ok(s) => {
            if !a.dry_run {
                crate::events::append(&Store::at(repo), "migrate", None, None);
            }
            println!(
                "{}imported {}, skipped {}, re-linked {}, {} source-only gap(s)",
                if a.dry_run { "(dry-run) " } else { "" },
                s.imported,
                s.skipped,
                s.relinked,
                s.source_only_gaps
            );
            ExitCode::SUCCESS
        }
        Err(e) => {
            eprintln!("error: {e}");
            ExitCode::FAILURE
        }
    }
}

pub fn why(repo: &Path, selector: &str) -> ExitCode {
    let store = Store::at(repo);
    if !store.exists() {
        eprintln!("error: no .evolving/ store here — run `ev init` first");
        return ExitCode::FAILURE;
    }
    let files = match store.read_all() {
        Ok(f) => f,
        Err(e) => {
            eprintln!("error: reading store: {e}");
            return ExitCode::FAILURE;
        }
    };
    let mut found = false;
    for (filename, raw) in &files {
        let t = match crate::tick::from_value(raw) {
            Ok(t) => t,
            Err(_) => continue,
        };
        if t.status != "live" {
            continue;
        }
        for g in &t.grounds {
            if let Some(Check::Test { reference, .. }) = &g.check {
                if reference.as_str() == selector {
                    found = true;
                    println!(
                        "{filename}\t{:?}\tguards: {:?} ({})",
                        t.decision, g.claim, g.supports
                    );
                }
            }
        }
    }
    if !found {
        eprintln!("{selector:?} guards nothing");
        return ExitCode::FAILURE;
    }
    ExitCode::SUCCESS
}

/// List every decision in the ledger: id, status, decision (sorted by id, deterministic).
pub fn list(repo: &Path) -> ExitCode {
    let store = Store::at(repo);
    if !store.exists() {
        eprintln!("error: no .evolving/ store here — run `ev init` first");
        return ExitCode::FAILURE;
    }
    let files = match store.read_all() {
        Ok(f) => f,
        Err(e) => {
            eprintln!("error: reading store: {e}");
            return ExitCode::FAILURE;
        }
    };
    // One pre-rendered line per tick, keyed by id so the output is deterministic. The bookkeeping
    // tags (authority, jurisdiction, source_ref) are appended inline when present — same one-line shape as show.
    let mut rows: Vec<String> = files
        .iter()
        .map(|(name, raw)| {
            let line = match crate::tick::from_value(raw) {
                Ok(t) => {
                    let mut l = format!("{name}\t{}\t{:?}", t.status, t.decision);
                    if let Some(a) = &t.authority {
                        l.push_str(&format!("\tauthority={a}"));
                    }
                    if let Some(j) = &t.jurisdiction {
                        l.push_str(&format!("\tjurisdiction={j}"));
                    }
                    if let Some(r) = &t.source_ref {
                        l.push_str(&format!("\tsource_ref={}", render_source_ref(r)));
                    }
                    l
                }
                Err(_) => format!("{name}\t?\t\"<unparseable>\""),
            };
            line
        })
        .collect();
    rows.sort();
    if rows.is_empty() {
        println!("no decisions yet");
        return ExitCode::SUCCESS;
    }
    for line in &rows {
        println!("{line}");
    }
    ExitCode::SUCCESS
}

/// A decision is "load-bearing" iff any of its grounds closes a road (`supports` starts with
/// `"rejected:"`). Those are the rulings a fresh agent must not re-walk, so they pin above the cap.
/// Detectable straight from the tick — 0-network, no receipts, no git.
fn load_bearing(t: &Tick) -> bool {
    t.grounds
        .iter()
        .any(|g| g.supports.starts_with("rejected:"))
}

/// Boot-read: the live user-ruled decisions and the roads they rejected. A near-zero-cost,
/// 0-network read (read_all only; no git, no receipts) for a fresh agent to load the
/// decisions it must respect and the options it must not re-propose. Load-bearing rulings
/// (those that closed a road) sort FIRST — pinned above the cap regardless of recency — then
/// by recency (held_since), then id. Capped to the effective limit, with a remainder footer
/// that counts how many hidden rulings closed a road so the elision stays visible.
pub fn brief(repo: &Path, limit: Option<usize>) -> ExitCode {
    let store = Store::at(repo);
    if !store.exists() {
        eprintln!("error: no .evolving/ store here — run `ev init` first");
        return ExitCode::FAILURE;
    }
    let files = match store.read_all() {
        Ok(f) => f,
        Err(e) => {
            eprintln!("error: reading store: {e}");
            return ExitCode::FAILURE;
        }
    };
    // The flag overrides config; 0 (here or in config) means "show all".
    let limit = limit.unwrap_or(crate::config::read(&store).brief_limit);
    // Keep only live, user-ruled decisions; carry the id so output is deterministic.
    let mut kept: Vec<(String, Tick)> = files
        .iter()
        .filter_map(|(name, raw)| crate::tick::from_value(raw).ok().map(|t| (name.clone(), t)))
        .filter(|(_, t)| t.status == "live" && t.authority.as_deref() == Some("user-ruled"))
        .collect();
    let lb = load_bearing;
    // Load-bearing first (true > false, so descending pins them), then most-recent-first by
    // held_since, then id descending — all deterministic.
    kept.sort_by(|a, b| {
        lb(&b.1)
            .cmp(&lb(&a.1))
            .then(b.1.held_since.cmp(&a.1.held_since))
            .then(b.0.cmp(&a.0))
    });
    if kept.is_empty() {
        println!("no user-ruled decisions");
        return ExitCode::SUCCESS;
    }
    let total = kept.len();
    // 0 means "show all"; otherwise cap at the limit (never past the end).
    let n = if limit == 0 { total } else { limit.min(total) };
    // Count load-bearing rulings about to be elided, before we truncate the shown set.
    let dropped_lb = kept[n..].iter().filter(|(_, t)| lb(t)).count();
    kept.truncate(n);
    for (_id, t) in &kept {
        println!("{}  [user-ruled]", t.decision);
        for g in &t.grounds {
            if let Some(option) = g.supports.strip_prefix("rejected:") {
                println!("  rejected {option}: {}", g.claim);
            }
        }
    }
    if total > n {
        let dropped = total - n;
        let lb_clause = if dropped_lb > 0 {
            format!(", {dropped_lb} with rejected roads")
        } else {
            String::new()
        };
        println!("… {dropped} more user-ruled decision(s){lb_clause} — `ev list` for all");
    }
    ExitCode::SUCCESS
}

/// Show the decision lineage from HEAD back to genesis (newest first).
pub fn log(repo: &Path) -> ExitCode {
    let store = Store::at(repo);
    if !store.exists() {
        eprintln!("error: no .evolving/ store here — run `ev init` first");
        return ExitCode::FAILURE;
    }
    let mut id = match store.read_head() {
        Ok(h) => h,
        Err(e) => {
            eprintln!("error: reading HEAD: {e}");
            return ExitCode::FAILURE;
        }
    };
    if id.is_empty() {
        println!("no decisions yet");
        return ExitCode::SUCCESS;
    }
    let mut seen = std::collections::HashSet::new();
    while !id.is_empty() {
        if !seen.insert(id.clone()) {
            break; // cycle guard (a content-addressed chain can't cycle, but never loop)
        }
        match store.read_tick(&id) {
            Ok(Some(t)) => {
                println!("{}\t{}\t{:?}", t.id, t.status, t.decision);
                id = t.parent_id;
            }
            Ok(None) => {
                eprintln!("warning: {id} not found (broken lineage)");
                break;
            }
            Err(e) => {
                eprintln!("error: reading {id}: {e}");
                return ExitCode::FAILURE;
            }
        }
    }
    ExitCode::SUCCESS
}

pub fn reopen(repo: &Path, id: &str) -> ExitCode {
    let store = Store::at(repo);
    let tick = match store.read_tick(id) {
        Ok(Some(t)) => t,
        Ok(None) => {
            eprintln!("error: no tick with id {id}");
            return ExitCode::FAILURE;
        }
        Err(e) => {
            eprintln!("error: reading {id}: {e}");
            return ExitCode::FAILURE;
        }
    };
    let config = crate::config::read(&store);
    let live_origin = crate::staleness::resolve(repo, &store, &config.staleness_ref, true);
    let ctx = live_ctx(&store, config.staleness_days, live_origin, None);

    crate::events::append(&store, "reopen", Some(id), None);
    println!("decision {}: {:?}", tick.id, tick.decision);
    if !tick.observe.is_empty() {
        println!("observe: {:?}", tick.observe);
    }
    if let Some(a) = &tick.authority {
        println!("authority: {a}");
    }
    if let Some(j) = &tick.jurisdiction {
        println!("jurisdiction: {j}");
    }
    if let Some(r) = &tick.source_ref {
        println!("source_ref: {}", render_source_ref(r));
    }
    for g in &tick.grounds {
        match &g.check {
            Some(Check::Test {
                reference,
                verified_at_sha,
                ..
            }) => {
                let receipts = crate::receipt::read_for(&store, reference).unwrap_or_default();
                let ts = triggered_since(repo, g, &receipts);
                let v = crate::verdict::verdict_for(g, &receipts, &ctx, ts);
                let now = v.label();
                let short = &verified_at_sha[..verified_at_sha.len().min(8)];
                println!(
                    "  [{}] {:?} — test {:?} frozen@{short} now: {now}",
                    g.supports, g.claim, reference
                );
            }
            Some(Check::Person { reference }) => {
                println!("  [{}] {:?} — person {:?}", g.supports, g.claim, reference);
            }
            None => {
                println!("  [{}] {:?}", g.supports, g.claim);
            }
        }
    }
    ExitCode::SUCCESS
}

/// Reproduce the two frozen golden vectors; non-zero if either id drifts.
fn self_test_golden() -> ExitCode {
    let genesis = Tick {
        id: String::new(),
        parent_id: "".into(),
        observe: "evaluating retrieval backend".into(),
        decision: "freeze the retrieval schema for v2".into(),
        grounds: vec![
            Ground {
                claim: "team still wants a frozen schema".into(),
                supports: "chosen".into(),
                check: Some(Check::Person {
                    reference: "Q3 infra review".into(),
                }),
            },
            Ground {
                claim: "pgvector would lock our schema".into(),
                supports: "rejected:pgvector".into(),
                check: None,
            },
        ],
        status: "live".into(),
        held_since: "".into(),
        blame: "Wang Yu".into(),
        authority: None,
        jurisdiction: None,
        source_ref: None,
        provenance: None,
    };
    let case1 = Tick {
        id: String::new(),
        parent_id: "7b21f0a4c8de".into(),
        observe: "multi-pod restore-safety counter — chat-room R2289→R2290".into(),
        decision: "restore-safety counter DB-backed; reject Redis".into(),
        grounds: vec![
            Ground {
                claim: "Argus introduces no Redis; multi-pod coord via existing DB".into(),
                supports: "chosen".into(),
                check: Some(Check::Test {
                    reference: "pytest tests/test_redis_absent.py".into(),
                    verified_at_sha: "d308afac1b2c3d4e5f60718293a4b5c6d7e8f901".into(),
                    counter_test: Some(
                        "pytest tests/test_redis_absent.py::test_redis_injection_flips_red".into(),
                    ),
                    liveness: Liveness {
                        platforms: vec!["linux-ci".into()],
                        triggered_by: vec!["pyproject.toml".into()],
                        surfaces: vec!["pyproject-deps".into()],
                    },
                }),
            },
            Ground {
                claim: "team still wants 0-Redis posture".into(),
                supports: "chosen".into(),
                check: Some(Check::Person {
                    reference: "Q3 infra review".into(),
                }),
            },
            Ground {
                claim: "Redis would add a new infra dependency".into(),
                supports: "rejected:Redis".into(),
                check: None,
            },
        ],
        status: "live".into(),
        held_since: "".into(),
        blame: "Wang Yu".into(),
        authority: None,
        jurisdiction: None,
        source_ref: None,
        provenance: None,
    };
    // A harvested binding: case1's first ground with counter_test omitted (None). Pins that
    // omit-on-None keeps every harvested id byte-stable — moving it would mean the payload changed.
    let mut harvested = case1.clone();
    if let Some(Check::Test { counter_test, .. }) = &mut harvested.grounds[0].check {
        *counter_test = None;
    }
    let mut ok = true;
    for (name, t, want) in [
        ("genesis", &genesis, "e2b337f53a1f"),
        ("case1", &case1, "638c47b0c9dd"),
        ("harvested", &harvested, "0cf784b51331"),
    ] {
        let got = compute_id(t);
        let pass = got == want;
        ok &= pass;
        println!(
            "{} {name}: {got} (want {want})",
            if pass { "✓" } else { "✗" }
        );
    }
    if ok {
        ExitCode::SUCCESS
    } else {
        ExitCode::FAILURE
    }
}