tix-tracker 0.8.0

//! `tix epic`: the epic lifecycle and association surface (mission
//! `epics-work-items-01M3BYW4`, WP05; FR-001, FR-002, FR-004, C-003, C-006).
//!
//! This module is a **thin adapter**. Every rule it appears to enforce is one
//! [`crate::epics`] already owns and [`crate::storage`] already applies:
//!
//! | concern | owner | how this module reaches it |
//! |---|---|---|
//! | identity, resolution (id first, name second) | `crate::epics` | [`epics::resolve_epic_id`], [`epics::resolve`] |
//! | lifecycle and validation | `crate::epics` | [`epics::create_epic`], [`epics::edit_epic`], [`epics::delete_epic`] |
//! | hierarchy navigation (parent, children, ancestors, depth) | `crate::epics` | [`epics::hierarchy`] |
//! | membership, child counts, progress, weight, blocked | `crate::epics` | [`epics::list_epics`], [`epics::EpicIndex::rollup`] |
//! | association mutations + History | `crate::storage` | [`Store::reference_epic`], [`Store::dereference_epic`], [`Store::bulk_reference`] |
//! | the wording of a refusal | `crate::epics` | [`EpicError`] rendered through `TixError` |
//!
//! Four properties are deliberate and are the ones a surface loses most easily:
//!
//! - **Every listing shows the id.** [`epics::epic_display`] is the one formatter,
//!   and `list` prints the id and the name in separate columns, so a rename can
//!   never be mistaken for a new epic (C-003).
//! - **Delete never deletes an issue or a child epic.** [`epics::delete_epic`]
//!   removes the registry entry and *reports* the affected issues and child epics;
//!   this module prints that report and adds no cascade and no `--cascade` flag
//!   (C-006).
//! - **Bulk is per-issue.** `add`, `remove` and `bulk-add` report one outcome per
//!   selector, and a rejection on one neither aborts nor rolls back the rest. There
//!   is no bulk-edit engine here: the scope is epic reference only, riding the
//!   existing service seams.
//! - **A task is an ordinary issue.** There is no task entity, file, or frontmatter
//!   key: `--labels task` plus a reference is a label and a reference, nothing more
//!   (C-001), and direct issue navigation stays available from every view.
//!
//! `tix epic` mutates `tix.toml` for its lifecycle verbs, so it is routed by
//! [`crate::cli::run`] — the process boundary that owns the mutable config —
//! exactly as `tix project` and `tix wip` are. The batch verbs return a **status**
//! rather than an error, so a partly-successful batch exits non-zero while every
//! outcome stays reported.

use std::io::IsTerminal;

use crate::cli::{EpicCommand, ExitCode};
use crate::config::{Config, EpicId};
use crate::epics::{
    self, Epic, EpicEdit, EpicHierarchy, EpicRollup, NewEpic, Patch, WeightedProgress,
};
use crate::error::{Result, TixError};
use crate::model::Issue;
use crate::relationships::{IssueView, RelationshipGraph};
use crate::storage::{BulkReferenceOutcome, Store};

/// Run one `tix epic` subcommand.
///
/// Returns an [`ExitCode`] rather than `()` because the batch verbs (`add`,
/// `remove`, `bulk-add`) carry a **status**: each selector is independent, so a
/// run where one selector failed is a completed command reporting non-zero, not an
/// error that discarded the rest.
pub fn run(config: &mut Config, store: &Store, command: &EpicCommand) -> Result<ExitCode> {
    match command {
        EpicCommand::Create {
            name,
            description,
            status,
            owner,
            start_date,
            due_date,
            weight,
            projects,
            milestone,
            cycle,
        } => create(
            config,
            store,
            name,
            description.as_deref(),
            status.as_deref(),
            owner.as_deref(),
            start_date.as_deref(),
            due_date.as_deref(),
            weight.as_deref(),
            projects.as_deref(),
            milestone.as_deref(),
            cycle.as_deref(),
        ),
        EpicCommand::Edit {
            reference,
            name,
            description,
            status,
            owner,
            start_date,
            due_date,
            weight,
            parent,
            projects,
            milestone,
            cycle,
        } => edit(
            config,
            store,
            reference,
            name.as_deref(),
            description.as_deref(),
            status.as_deref(),
            owner.as_deref(),
            start_date.as_deref(),
            due_date.as_deref(),
            weight.as_deref(),
            parent.as_deref(),
            projects.as_deref(),
            milestone.as_deref(),
            cycle.as_deref(),
        ),
        EpicCommand::List => list(config, store),
        EpicCommand::Show { reference } => show(config, store, reference),
        EpicCommand::Navigate { reference } => navigate(config, store, reference),
        EpicCommand::Delete { reference, yes } => delete(config, store, reference, *yes),
        // `add` and `bulk-add` are the same operation under two spellings: the
        // single-issue form and the explicitly batch form process every selector
        // independently, and separating their behaviour would give one of them a
        // second set of rules.
        EpicCommand::Add { reference, issues } | EpicCommand::BulkAdd { reference, issues } => {
            reference_from_epic(config, store, reference, issues)
        }
        EpicCommand::Remove { reference, issues } => {
            dereference_from_epic(config, store, reference, issues)
        }
    }
}

// ---------------------------------------------------------------------------
// Lifecycle
// ---------------------------------------------------------------------------

/// Persist the registry after an accepted lifecycle change.
///
/// `Config::validate` runs first, so a change that would make `tix.toml`
/// unloadable is refused before it is written rather than discovered by the next
/// command. The path is the shared [`crate::commands::views::config_path`], so
/// registry writes go through the one atomic-save path rather than a second copy
/// of it.
fn save(config: &mut Config, store: &Store) -> Result<()> {
    config.validate()?;
    let path = crate::commands::views::config_path(store);
    config
        .save(&path)
        .map_err(|error| TixError::Config(format!("could not save `{}`: {error}", path.display())))
}

/// `tix epic create <name> [flags]`.
#[allow(clippy::too_many_arguments)]
fn create(
    config: &mut Config,
    store: &Store,
    name: &str,
    description: Option<&str>,
    status: Option<&str>,
    owner: Option<&str>,
    start_date: Option<&str>,
    due_date: Option<&str>,
    weight: Option<&str>,
    projects: Option<&str>,
    milestone: Option<&str>,
    cycle: Option<&str>,
) -> Result<ExitCode> {
    let new = NewEpic {
        name: name.to_string(),
        description: description.map(String::from),
        status: status.map(String::from),
        owner: owner.map(String::from),
        start_date: trim_optional(start_date),
        due_date: trim_optional(due_date),
        weight: create_weight(weight)?,
        // Shape only, never resolution: the service validates each id's shape and
        // keeps a dangling-but-well-formed one for repair (C-005).
        projects: projects
            .map(crate::commands::parse_csv_list)
            .unwrap_or_default(),
        milestone: trim_optional(milestone),
        cycle: trim_optional(cycle),
    };
    // The service allocates the id and validates name, dates and weight, so an
    // invalid request refuses here with the registry untouched (nothing to persist).
    let epic = epics::create_epic(config, &new)?;
    save(config, store)?;
    println!("Created {}", epics::epic_display(&epic.id, &epic.name));
    Ok(ExitCode::Success)
}

/// `tix epic edit <id> [--field …]`.
///
/// A `--name` change is a **label change only**: [`epics::edit_epic`] touches the
/// record, never the registry key, so nothing is re-keyed and every reference and
/// derived figure survives (C-003). A `--parent` change is validated by the
/// service's cycle walk before any write (contract §3).
#[allow(clippy::too_many_arguments)]
fn edit(
    config: &mut Config,
    store: &Store,
    reference: &str,
    name: Option<&str>,
    description: Option<&str>,
    status: Option<&str>,
    owner: Option<&str>,
    start_date: Option<&str>,
    due_date: Option<&str>,
    weight: Option<&str>,
    parent: Option<&str>,
    projects: Option<&str>,
    milestone: Option<&str>,
    cycle: Option<&str>,
) -> Result<ExitCode> {
    let edit = EpicEdit {
        name: name.map_or(Patch::Unchanged, |value| Patch::Set(value.to_string())),
        description: text_patch(description),
        status: text_patch(status),
        owner: text_patch(owner),
        start_date: date_patch(start_date),
        due_date: date_patch(due_date),
        weight: weight_patch(weight)?,
        parent: text_patch(parent),
        // `--projects` on an epic **sets the full list**; an empty value clears it.
        projects: match projects {
            None => Patch::Unchanged,
            Some(value) if value.trim().is_empty() => Patch::Clear,
            Some(value) => Patch::Set(crate::commands::parse_csv_list(value)),
        },
        milestone: text_patch(milestone),
        cycle: text_patch(cycle),
    };
    if edit.name.is_unchanged()
        && edit.description.is_unchanged()
        && edit.status.is_unchanged()
        && edit.owner.is_unchanged()
        && edit.start_date.is_unchanged()
        && edit.due_date.is_unchanged()
        && edit.weight.is_unchanged()
        && edit.parent.is_unchanged()
        && edit.projects.is_unchanged()
        && edit.milestone.is_unchanged()
        && edit.cycle.is_unchanged()
    {
        return Err(epic_edit_requires_a_field());
    }
    let epic = epics::edit_epic(config, reference, &edit)?;
    save(config, store)?;
    println!("Updated {}", epics::epic_display(&epic.id, &epic.name));
    Ok(ExitCode::Success)
}

/// `tix epic list` — declaration order, `id<TAB>name<TAB>members<TAB>children`.
///
/// The id is a column of its own rather than a decoration, because selecting by id
/// is the contract and a listing that hides the id makes a rename look like a new
/// epic (C-003). One tab-separated row per epic is greppable and deterministic.
fn list(config: &Config, store: &Store) -> Result<ExitCode> {
    for line in listing_lines(config, &store.list_all()?) {
        println!("{line}");
    }
    Ok(ExitCode::Success)
}

/// One tab-separated row per epic: `id<TAB>name<TAB>member count<TAB>child count`.
///
/// A pure function so the id-alongside-name property (C-003) is assertable without
/// capturing a process's stdout.
pub fn listing_lines(config: &Config, issues: &[Issue]) -> Vec<String> {
    epics::list_epics(config, issues)
        .iter()
        .map(|epic| {
            format!(
                "{}\t{}\t{}\t{}",
                epic.id, epic.name, epic.member_count, epic.child_count
            )
        })
        .collect()
}

/// `tix epic show <id>` — the record, its figures, its hierarchy and its members.
///
/// Every figure is the service's typed value ([`epics::EpicIndex::rollup`]) — one
/// call, no second computation (C-008). A member is printed through the shared
/// `MemberRef` renderer (`#<number> <title>`), so a member never shows a stale
/// title: the label is derived on read and never stored. Ids are shown everywhere,
/// because without them the output is not actionable.
fn show(config: &Config, store: &Store, reference: &str) -> Result<ExitCode> {
    let issues = store.list_all()?;
    let index = epics::EpicIndex::build(config, &issues);
    let epic = index.resolve(reference)?.clone();
    // The graph is built here from the **existing** derived reads (the relationship
    // service owns blocked state), and the targets from the existing planner
    // lookups; this module computes no figure of its own.
    let targets = reference_targets(config, store)?;
    let (graph_issues, done_column) = store.graph_source()?;
    let views: Vec<IssueView<'_>> = graph_issues.iter().map(Issue::issue_view).collect();
    let graph = RelationshipGraph::new(&views, &done_column);
    let rollup = index.rollup(config, reference, &targets, &graph)?;
    for line in record_lines(&epic, Some(&rollup)) {
        println!("{line}");
    }
    Ok(ExitCode::Success)
}

/// One `key: value` line per record field, then the derived figures, then one line
/// per child epic and one per member.
///
/// Pure, so the record/member rendering is assertable without capturing stdout. The
/// figure lines are emitted only when the service's rollup is supplied: a caller
/// with no snapshot renders the record alone rather than inventing zeros, the same
/// distinction the `-`-for-absent spelling draws for the optional fields.
pub fn record_lines(epic: &Epic, rollup: Option<&EpicRollup>) -> Vec<String> {
    let mut lines = vec![
        format!("id: {}", epic.id),
        format!("name: {}", epic.name),
        format!(
            "description: {}",
            epic.description.as_deref().unwrap_or("-")
        ),
        format!("status: {}", epic.status.as_deref().unwrap_or("-")),
        format!("owner: {}", epic.owner.as_deref().unwrap_or("-")),
        format!("start-date: {}", epic.start_date.as_deref().unwrap_or("-")),
        format!("due-date: {}", epic.due_date.as_deref().unwrap_or("-")),
        format!(
            "weight: {}",
            epic.weight
                .map_or_else(|| "-".to_string(), |w| w.to_string())
        ),
        format!("parent: {}", epic.parent.as_deref().unwrap_or("-")),
        format!("projects: {}", join_or_dash(&epic.projects)),
        format!("milestone: {}", epic.milestone.as_deref().unwrap_or("-")),
        format!("cycle: {}", epic.cycle.as_deref().unwrap_or("-")),
        format!("children: {}", epic.child_count),
        format!("members: {}", epic.member_count),
    ];
    if let Some(rollup) = rollup {
        lines.push(format!(
            "progress: {}/{}",
            rollup.progress.done, rollup.progress.total
        ));
        lines.push(format!(
            "weighted: {}",
            weighted_summary(&rollup.weighted_progress)
        ));
        lines.push(format!("blocked: {}", rollup.blocked));
        lines.push(format!(
            "missing-references: {}",
            rollup.missing_references.len()
        ));
    }
    lines.extend(
        epic.children
            .iter()
            .map(|child| format!("  child: {}", child.display)),
    );
    lines.extend(
        epic.members
            .iter()
            .map(|member| format!("  {}", member.display)),
    );
    lines
}

/// The one spelling of the weight-aware figure.
fn weighted_summary(weighted: &WeightedProgress) -> String {
    let percent = weighted
        .percent
        .map_or_else(|| "-".to_string(), |p| format!("{p}%"));
    format!(
        "{}/{} ({percent}; {} weighted, {} unweighted child epic(s))",
        weighted.done_weight,
        weighted.total_weight,
        weighted.weighted_children,
        weighted.unweighted_children
    )
}

/// `tix epic navigate <id>` — parent, children, ancestors and depth, parent-first.
///
/// The layout is stable and **parent-first**: the ancestors root-first, then the
/// epic itself, then its children, then its members. The member list is followed by
/// an explicit note that a member is an ordinary issue reachable with `tix show`,
/// so FR-004's "direct issue navigation stays available" is visible rather than
/// merely implied.
fn navigate(config: &Config, store: &Store, reference: &str) -> Result<ExitCode> {
    let issues = store.list_all()?;
    let index = epics::EpicIndex::build(config, &issues);
    let hierarchy = index.hierarchy(reference)?;
    let epic = index.resolve(reference)?.clone();
    for line in navigation_lines(&hierarchy, &epic) {
        println!("{line}");
    }
    Ok(ExitCode::Success)
}

/// The parent-first navigation rendering.
///
/// Pure, so ordering and depth are assertable without capturing stdout. A recorded
/// parent that no longer exists is rendered explicitly (contract §3.4) rather than
/// silently dropped.
pub fn navigation_lines(hierarchy: &EpicHierarchy, epic: &Epic) -> Vec<String> {
    let mut lines = vec!["ancestors:".to_string()];
    if hierarchy.ancestors.is_empty() {
        lines.push("  -".to_string());
    }
    for ancestor in &hierarchy.ancestors {
        lines.push(format!("  {}", ancestor.display));
    }
    match &hierarchy.parent {
        Some(parent) => lines.push(format!("parent: {}", parent.display)),
        None => lines.push("parent: -".to_string()),
    }
    if let Some(unresolved) = &hierarchy.unresolved {
        lines.push(format!("unresolved-parent: {}", unresolved.reason));
    }
    lines.push(format!(
        "epic: {}",
        epics::epic_display(&epic.id, &epic.name)
    ));
    lines.push(format!("depth: {}", hierarchy.depth));
    lines.push(format!("children: {}", hierarchy.child_count));
    for child in &hierarchy.children {
        lines.push(format!("  {}", child.display));
    }
    lines.push(format!("issues: {}", epic.member_count));
    for member in &epic.members {
        lines.push(format!("  {}", member.display));
    }
    lines.push(
        "note: members are ordinary issues; navigate one directly with `tix show <number>`"
            .to_string(),
    );
    lines
}

/// `tix epic delete <id> [--yes]`.
///
/// Removes the registry entry **only**. The affected issues are reported — number
/// and title — and their references are retained as diagnosable missing
/// references, and the child epics keep their recorded parent, which then reads as
/// an unresolved parent. There is no cascade and no `--cascade` flag: deleting an
/// epic must never delete a member issue or a child epic (C-006).
///
/// Confirmation follows [`crate::commands::delete`] and `tix project delete`:
/// `--yes` skips the prompt and a non-TTY stdin deletes immediately, so the command
/// is scriptable and TTY-free.
fn delete(config: &mut Config, store: &Store, reference: &str, yes: bool) -> Result<ExitCode> {
    let issues = store.list_all()?;
    // Resolved before the prompt so an unknown id refuses with nothing written and
    // nothing asked.
    let epic = epics::resolve(config, &issues, reference)?;

    let mut confirmed = yes || !std::io::stdin().is_terminal();
    if !confirmed {
        eprint!(
            "Delete epic '{}'? [y/N] ",
            epics::epic_display(&epic.id, &epic.name)
        );
        let mut line = String::new();
        std::io::stdin()
            .read_line(&mut line)
            .map_err(TixError::Io)?;
        confirmed = line.trim().eq_ignore_ascii_case("y");
        if !confirmed {
            eprintln!("aborted");
        }
    }
    if !confirmed {
        return Ok(ExitCode::Success);
    }

    // The impact notice, printed **before** the deletion so it is on screen
    // alongside the confirmation — the convention `tix delete` follows. `eprint!`
    // because it is a warning about what is about to happen, not data.
    eprint!("{}", impact_notice(&epic));

    let deletion = epics::delete_epic(config, reference, &issues)?;
    save(config, store)?;
    println!(
        "Deleted epic {}",
        epics::epic_display(&deletion.id, &deletion.name)
    );
    Ok(ExitCode::Success)
}

/// The delete-time impact notice, or the empty string when nothing references the
/// epic.
///
/// One `tix epic delete` removes **exactly one registry entry**. The issues that
/// referenced the epic keep their references, and the child epics keep their
/// recorded parent; both read as repairable diagnostics afterwards, which `tix
/// lint` names. Neither is deleted or modified.
pub fn impact_notice(epic: &Epic) -> String {
    let mut out = String::new();
    if !epic.members.is_empty() {
        let count = epic.members.len();
        // The verb and the pronoun agree with the noun, chosen by the same `len()`
        // test: "1 issue still references … It is not deleted" vs "N issues still
        // reference … They are not deleted".
        if count == 1 {
            out.push_str(
                "Note: 1 issue still references this epic and keeps the reference as a missing \
                 epic reference.\nIt is not deleted or modified; `tix lint` reports the dangling \
                 reference until it is repaired.\n",
            );
        } else {
            out.push_str(&format!(
                "Note: {count} issues still reference this epic and keep the reference as a \
                 missing epic reference.\nThey are not deleted or modified; `tix lint` reports \
                 the dangling reference until it is repaired.\n"
            ));
        }
        for member in &epic.members {
            out.push_str(&format!("  {}\n", member.display));
        }
    }
    if !epic.children.is_empty() {
        let count = epic.children.len();
        if count == 1 {
            out.push_str(
                "Note: 1 child epic records this epic as its parent and keeps the reference as \
                 an unresolved parent.\nIt is not deleted or modified.\n",
            );
        } else {
            out.push_str(&format!(
                "Note: {count} child epics record this epic as their parent and keep the \
                 reference as an unresolved parent.\nThey are not deleted or modified.\n"
            ));
        }
        for child in &epic.children {
            out.push_str(&format!("  {}\n", child.display));
        }
    }
    out
}

// ---------------------------------------------------------------------------
// Association from the epic side
// ---------------------------------------------------------------------------

/// `tix epic add|bulk-add <id> <sel…>`.
///
/// Each selector is processed independently through [`Store::bulk_reference`],
/// which is the service-backed batch seam: one rejection is reported beside the
/// rest rather than aborting them, and each accepted change appends exactly one
/// History entry. The epic reference is resolved **once**, up front, so an unknown
/// epic refuses before any write.
fn reference_from_epic(
    config: &Config,
    store: &Store,
    reference: &str,
    selectors: &[String],
) -> Result<ExitCode> {
    let id = epics::resolve_epic_id(&config.epics, reference)?;
    let display = display_for(config, &id);
    let outcomes = store.bulk_reference(id.as_str(), selectors)?;
    report(&display, "referenced", outcomes)
}

/// `tix epic remove <id> <sel…>`.
///
/// Drops only the reference (never the issue). The reference is resolved when it
/// names a live epic and otherwise used **verbatim**, which is the repair path
/// C-005 promises: a stale stored id can still be removed. Each selector is
/// independent.
fn dereference_from_epic(
    config: &Config,
    store: &Store,
    reference: &str,
    selectors: &[String],
) -> Result<ExitCode> {
    // The resolve-or-keep-verbatim rule is the service's one classifier (WP09 item B).
    let needle = epics::dereference_needle(&config.epics, reference);
    let display = match epics::resolve_epic_id(&config.epics, reference) {
        Ok(id) => display_for(config, &id),
        Err(_) => format!("`{reference}`"),
    };
    let mut code = ExitCode::Success;
    let mut changed = 0usize;
    let mut unchanged = 0usize;
    let mut failed = 0usize;
    for selector in selectors {
        match store.dereference_epic(selector, &needle) {
            Ok(applied) if applied.changed => {
                changed += 1;
                println!("dereferenced {selector}");
            }
            Ok(_) => {
                unchanged += 1;
                println!("dereferenced {selector} (was not referenced)");
            }
            Err(error) => {
                failed += 1;
                eprintln!("{}", crate::error::render_error(&error));
                if code == ExitCode::Success {
                    code = crate::cli::exit_code_for(&error);
                }
            }
        }
    }
    println!(
        "dereferenced {changed} of {} issue(s) from {display}{}{}",
        selectors.len(),
        unchanged_note(unchanged),
        failure_note(failed)
    );
    Ok(code)
}

/// Report a batch of reference outcomes: one line per issue, then a summary.
///
/// Successes and idempotent no-ops go to stdout (they are the data the user asked
/// about); a refusal goes to stderr, because a consumer redirecting stdout must not
/// find a diagnostic in it. The returned code is the **first** failure's mapped
/// code, so a partly-successful batch exits non-zero while every outcome stays
/// reported.
fn report(display: &str, verb: &str, outcomes: Vec<BulkReferenceOutcome>) -> Result<ExitCode> {
    let total = outcomes.len();
    let mut code = ExitCode::Success;
    let mut changed = 0usize;
    let mut unchanged = 0usize;
    let mut failed = 0usize;
    for outcome in outcomes {
        match outcome.outcome {
            Ok(applied) if applied.changed => {
                changed += 1;
                println!("{verb} {}", outcome.selector);
            }
            Ok(_) => {
                unchanged += 1;
                println!("{verb} {} (already {verb})", outcome.selector);
            }
            Err(error) => {
                failed += 1;
                eprintln!("{}", crate::error::render_error(&error));
                if code == ExitCode::Success {
                    code = crate::cli::exit_code_for(&error);
                }
            }
        }
    }
    println!(
        "{verb} {changed} of {total} issue(s) with {display}{}{}",
        unchanged_note(unchanged),
        failure_note(failed)
    );
    Ok(code)
}

/// ` (N unchanged)`, or nothing when every outcome changed something.
fn unchanged_note(unchanged: usize) -> String {
    if unchanged == 0 {
        String::new()
    } else {
        format!(" ({unchanged} unchanged)")
    }
}

/// `; N failed`, or nothing when the batch had no failure.
fn failure_note(failed: usize) -> String {
    if failed == 0 {
        String::new()
    } else {
        format!("; {failed} failed")
    }
}

/// The display form for a resolved id: the registry name beside the id.
fn display_for(config: &Config, id: &EpicId) -> String {
    match config.epics.get(id.as_str()) {
        Some(record) => epics::epic_display(id, &record.name),
        None => format!("`{id}`"),
    }
}

// ---------------------------------------------------------------------------
// Shared helpers for the create/edit cores
// ---------------------------------------------------------------------------

/// Resolve and validate a comma-separated `--epics` value, in first-seen order.
///
/// Every reference is resolved through the service **before** the caller writes
/// anything, so an unknown id refuses the whole operation rather than leaving a
/// half-referenced issue. Resolution also collapses duplicates: `e-1,e-1` and
/// `Harden,e-1` both name one epic, and one reference is what gets written.
pub fn resolve_epics(config: &Config, raw: &str) -> Result<Vec<String>> {
    let mut out: Vec<String> = Vec::new();
    for reference in crate::commands::parse_csv_list(raw) {
        let id = epics::resolve_epic_id(&config.epics, &reference)?.to_string();
        if !out.contains(&id) {
            out.push(id);
        }
    }
    Ok(out)
}

/// Reference a freshly created issue from the resolved epic ids.
///
/// One [`Store::reference_epic`] per id, so the History entry and the idempotence
/// rule are the service's, not a second implementation here. The ids were resolved
/// before the issue existed, so a refusal cannot leave a half-referenced create.
pub fn reference_created(store: &Store, issue: &Issue, ids: &[String]) -> Result<()> {
    for id in ids {
        store.reference_epic(&issue.number.to_string(), id)?;
    }
    Ok(())
}

/// The validated reference inputs of one `tix edit`, ready to apply.
///
/// Produced by [`plan_edit_epics`] **before** any write, so a refusal leaves every
/// file byte-identical (T025 step 5).
#[derive(Debug)]
pub struct EpicEditPlan {
    add_ids: Vec<String>,
    remove_ids: Vec<String>,
    clear: bool,
}

/// Resolve the `tix edit` epic-reference inputs without writing anything.
///
/// `clear` is `--epics ""`; an absent flag is an empty plan that changes nothing.
/// An unresolvable `--remove-epic` reference is refused as `unknown_epic` **unless**
/// the issue still carries it verbatim — removing a stale id is the repair path,
/// and refusing it would strand the reference. A `--remove-epic` that resolves to a
/// live epic the issue does not carry is an idempotent no-op, exactly as
/// `--remove-project` is.
pub fn plan_edit_epics(
    config: &Config,
    store: &Store,
    selector: &str,
    add: &[String],
    remove: &[String],
    clear: bool,
) -> Result<EpicEditPlan> {
    let mut add_ids: Vec<String> = Vec::new();
    for reference in add {
        let id = epics::resolve_epic_id(&config.epics, reference)?.to_string();
        if !add_ids.contains(&id) {
            add_ids.push(id);
        }
    }
    let remove_ids: Vec<String> = remove
        .iter()
        .map(|reference| epics::dereference_needle(&config.epics, reference))
        .collect();
    let stored = store.resolve_issue(selector)?.epics.unwrap_or_default();
    for reference in &remove_ids {
        // A reference the registry resolves to a live epic is always acceptable (a
        // no-op if absent). One it does not resolve is only acceptable when the
        // issue still carries it verbatim.
        let known = epics::resolve_epic_id(&config.epics, reference).is_ok();
        if !known && !stored.iter().any(|id| id == reference) {
            return Err(epics::EpicError::UnknownEpic {
                reference: reference.clone(),
            }
            .into());
        }
    }
    Ok(EpicEditPlan {
        add_ids,
        remove_ids,
        clear,
    })
}

/// Apply a validated epic-reference plan through the store, reporting whether
/// anything was actually applied.
///
/// Order is clear → remove → add, so `tix edit <n> --epics "" --add-epic e-1` ends
/// with exactly the added reference. Every mutation goes through
/// [`Store::reference_epic`]/[`Store::dereference_epic`], so `updated` is bumped and
/// the History entry appended in the one place that owns both.
///
/// The `bool` is `true` when at least one mutation changed something, so the
/// caller's success line does not claim a write that never happened.
pub fn apply_edit_epics(store: &Store, selector: &str, plan: &EpicEditPlan) -> Result<bool> {
    let mut changed = false;
    if plan.clear {
        let stored = store.resolve_issue(selector)?.epics.unwrap_or_default();
        for id in &stored {
            changed |= store.dereference_epic(selector, id)?.changed;
        }
    }
    for id in &plan.remove_ids {
        changed |= store.dereference_epic(selector, id)?.changed;
    }
    for id in &plan.add_ids {
        changed |= store.reference_epic(selector, id)?.changed;
    }
    Ok(changed)
}

/// The refusal `tix epic edit` prints when no field flag was given.
fn epic_edit_requires_a_field() -> TixError {
    TixError::InvalidInput(
        "no fields to change; pass at least one of --name, --description, --status, \
         --owner, --start-date, --due-date, --weight, --parent, --projects, \
         --milestone or --cycle"
            .to_string(),
    )
}

/// A blank value clears an optional text field; a written one sets it.
fn text_patch(value: Option<&str>) -> Patch<String> {
    match value {
        None => Patch::Unchanged,
        Some(text) if text.trim().is_empty() => Patch::Clear,
        Some(text) => Patch::Set(text.to_string()),
    }
}

/// A blank value clears a date field; a written one is passed through trimmed.
fn date_patch(value: Option<&str>) -> Patch<String> {
    match value {
        None => Patch::Unchanged,
        Some(text) if text.trim().is_empty() => Patch::Clear,
        Some(text) => Patch::Set(text.trim().to_string()),
    }
}

/// A weight patch: absent keeps it, blank clears it, a written value is parsed.
fn weight_patch(value: Option<&str>) -> Result<Patch<i64>> {
    match value {
        None => Ok(Patch::Unchanged),
        Some(text) if text.trim().is_empty() => Ok(Patch::Clear),
        Some(text) => Ok(Patch::Set(parse_weight(text)?)),
    }
}

/// A create-time weight: absent or blank means unset.
fn create_weight(value: Option<&str>) -> Result<Option<i64>> {
    match value {
        None => Ok(None),
        Some(text) if text.trim().is_empty() => Ok(None),
        Some(text) => Ok(Some(parse_weight(text)?)),
    }
}

/// Parse a `--weight` integer, naming the service's diagnostic kind.
///
/// A non-integer is a command-level parse refusal, so it cannot come from the
/// service; it is worded with the same `invalid_weight` kind so the user sees one
/// name for one problem. The **positivity** rule stays the service's.
fn parse_weight(text: &str) -> Result<i64> {
    text.trim().parse::<i64>().map_err(|_| {
        TixError::InvalidInput(format!(
            "{}: epic weight must be an integer; got `{text}`",
            epics::EpicDiagnosticKind::InvalidWeight
        ))
    })
}

/// A trimmed, non-blank optional string, or `None`.
fn trim_optional(value: Option<&str>) -> Option<String> {
    value
        .map(str::trim)
        .filter(|text| !text.is_empty())
        .map(String::from)
}

/// The elements joined by `, `, or `-` when the list is empty.
fn join_or_dash(values: &[String]) -> String {
    if values.is_empty() {
        "-".to_string()
    } else {
        values.join(", ")
    }
}

/// The reference targets for one snapshot, consumed from their owners.
///
/// The milestone and cycle names come from the existing [`crate::planning::Planner`]
/// lookups and the project ids from the project registry — no second milestone,
/// cycle, or project store (research R2, R6).
fn reference_targets(config: &Config, store: &Store) -> Result<epics::ReferenceTargets> {
    let root = Config::project_root(&store.issues_dir).unwrap_or_else(|| store.issues_dir.clone());
    let planner = crate::planning::Planner::from_config(config.clone(), root);
    epics::ReferenceTargets::from_planner(&planner)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::config::EpicConfiguration;
    use std::fs;
    use tempfile::TempDir;

    /// A store over a temp dir whose persisted registry declares `epics`, with
    /// `issues` issues (numbers `1..=issues`) titled `Issue N`.
    ///
    /// The registry is written to `tix.toml`, not merely held in memory, so a test
    /// that removes an epic can compare a real registry file before and after.
    fn store_with(epics: &[(&str, &str)], issues: usize) -> (TempDir, Store) {
        let tmp = TempDir::new().unwrap();
        let dir = tmp.path().join("issues");
        fs::create_dir_all(&dir).unwrap();
        let config_path = tmp.path().join("tix.toml");
        let mut config = Config {
            issues_dir: dir.clone(),
            ..Config::default()
        };
        config.layout.directory = "{assignee}".to_string();
        config.layout.move_on_change = false;
        for (id, name) in epics {
            config.epics.insert(
                (*id).to_string(),
                EpicConfiguration {
                    name: (*name).to_string(),
                    ..EpicConfiguration::default()
                },
            );
        }
        config.save(&config_path).unwrap();
        let config = Config::load_with_warning(&config_path, |_| {}).unwrap();
        let store = Store {
            issues_dir: dir.clone(),
            config,
        };
        for number in 1..=issues {
            write_issue(
                &store,
                u32::try_from(number).unwrap(),
                &format!("Issue {number}"),
                &[],
            );
        }
        (tmp, store)
    }

    /// A store whose epic `e-1` records a parent id that is not in the registry.
    fn store_with_unresolved_parent() -> (TempDir, Store) {
        let tmp = TempDir::new().unwrap();
        let dir = tmp.path().join("issues");
        fs::create_dir_all(&dir).unwrap();
        let config_path = tmp.path().join("tix.toml");
        let mut config = Config {
            issues_dir: dir.clone(),
            ..Config::default()
        };
        config.layout.directory = "{assignee}".to_string();
        config.layout.move_on_change = false;
        config.epics.insert(
            "e-1".to_string(),
            EpicConfiguration {
                name: "Orphan".to_string(),
                parent: Some("e-gone".to_string()),
                ..EpicConfiguration::default()
            },
        );
        config.save(&config_path).unwrap();
        let config = Config::load_with_warning(&config_path, |_| {}).unwrap();
        let store = Store {
            issues_dir: dir,
            config,
        };
        (tmp, store)
    }

    /// Write one issue file with an optional `epics` list.
    fn write_issue(store: &Store, number: u32, title: &str, epics: &[&str]) {
        let mut frontmatter =
            format!("---\nnumber: {number}\ntitle: \"{title}\"\nstatus: \"todo\"\nlabels: []\n");
        if !epics.is_empty() {
            frontmatter.push_str("epics:\n");
            for id in epics {
                frontmatter.push_str(&format!("- {id}\n"));
            }
        }
        frontmatter.push_str("---\n");
        fs::write(
            store
                .issues_dir
                .join(format!("2026-01-{number:02}-issue-{number}.md")),
            frontmatter,
        )
        .unwrap();
    }

    /// The registry file's bytes, for a "nothing else changed" assertion.
    fn registry(store: &Store) -> String {
        fs::read_to_string(registry_path(store)).unwrap()
    }

    /// The registry file beside the store's issues dir.
    fn registry_path(store: &Store) -> std::path::PathBuf {
        Config::project_root(&store.issues_dir)
            .unwrap()
            .join("tix.toml")
    }

    fn issue_bytes(store: &Store, number: u32) -> String {
        fs::read_to_string(
            store
                .issues_dir
                .join(format!("2026-01-{number:02}-issue-{number}.md")),
        )
        .unwrap()
    }

    // -- T022 — lifecycle ---------------------------------------------------

    #[test]
    fn the_listing_shows_each_epic_id_and_name_alongside_its_counts() {
        let (_tmp, store) = store_with(&[("e-1", "Harden"), ("e-2", "Docs")], 0);
        // e-2 is a child of e-1, so its child count is derived.
        let mut config = store.config.clone();
        config.epics.get_mut("e-2").unwrap().parent = Some("e-1".to_string());
        let lines = listing_lines(&config, &store.list_all().unwrap());
        assert_eq!(lines[0], "e-1\tHarden\t0\t1");
        assert_eq!(lines[1], "e-2\tDocs\t0\t0");
        // The id is present as a field of its own, not decoration (C-003).
        assert!(lines[0].contains("e-1"));
        assert!(lines[0].contains("Harden"));
    }

    #[test]
    fn create_allocates_an_id_and_refuses_a_duplicate_name() {
        let (_tmp, store) = store_with(&[], 0);
        let mut config = store.config.clone();
        create(
            &mut config,
            &store,
            "Harden",
            None,
            None,
            Some("alice"),
            None,
            None,
            Some("3"),
            Some("p-1"),
            None,
            None,
        )
        .unwrap();
        assert_eq!(config.epics.len(), 1);
        let (id, record) = config.epics.iter().next().unwrap();
        assert_eq!(record.name, "Harden");
        assert_eq!(record.owner.as_deref(), Some("alice"));
        assert_eq!(record.weight, Some(3));
        // A well-formed project id that names nothing is stored, not refused.
        assert_eq!(record.projects, vec!["p-1".to_string()]);
        assert!(id.starts_with("e-"), "an allocated id: {id}");

        // The same name (case-folded) is refused, and the registry is unchanged.
        let before = registry(&store);
        let error = create(
            &mut config,
            &store,
            "harden",
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
        )
        .expect_err("a duplicate name is refused");
        assert!(
            error.to_string().contains("duplicate_name"),
            "the named diagnostic: {error}"
        );
        assert_eq!(config.epics.len(), 1);
        assert_eq!(registry(&store), before, "nothing written");
    }

    #[test]
    fn edit_renames_the_label_and_keeps_the_id() {
        let (_tmp, store) = store_with(&[("e-1", "Harden")], 1);
        write_issue(&store, 1, "Issue 1", &["e-1"]);
        let mut config = store.config.clone();
        edit(
            &mut config,
            &store,
            "e-1",
            Some("Harden the sync path"),
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
        )
        .unwrap();
        // The registry key is untouched — nothing is re-keyed (C-003).
        assert!(config.epics.contains_key("e-1"));
        assert_eq!(config.epics["e-1"].name, "Harden the sync path");
        // The reference resolves through the same id after the rename.
        let epic = epics::resolve(&config, &store.list_all().unwrap(), "e-1").unwrap();
        assert_eq!(epic.name, "Harden the sync path");
        assert_eq!(epic.member_count, 1);
    }

    #[test]
    fn edit_refuses_a_self_parent_and_a_cycle_without_writing() {
        let (_tmp, store) = store_with(&[("e-1", "A"), ("e-2", "B")], 0);
        let mut config = store.config.clone();
        // e-2 under e-1 is fine.
        edit(
            &mut config,
            &store,
            "e-2",
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            Some("e-1"),
            None,
            None,
            None,
        )
        .unwrap();
        assert_eq!(config.epics["e-2"].parent.as_deref(), Some("e-1"));

        // Self-parent is refused.
        let before = registry(&store);
        let error = edit(
            &mut config,
            &store,
            "e-1",
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            Some("e-1"),
            None,
            None,
            None,
        )
        .expect_err("self-parent");
        assert!(error.to_string().contains("self_parent"), "{error}");

        // Closing the loop (e-1 under e-2) is refused.
        let error = edit(
            &mut config,
            &store,
            "e-1",
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            Some("e-2"),
            None,
            None,
            None,
        )
        .expect_err("cycle");
        assert!(error.to_string().contains("cycle"), "{error}");
        assert_eq!(registry(&store), before, "nothing written on a refusal");
    }

    #[test]
    fn edit_with_no_fields_is_a_usage_error() {
        let (_tmp, store) = store_with(&[("e-1", "A")], 0);
        let mut config = store.config.clone();
        let error = edit(
            &mut config,
            &store,
            "e-1",
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
            None,
        )
        .expect_err("a fieldless edit is refused");
        assert!(error.to_string().contains("no fields to change"), "{error}");
    }

    // -- T023 — delete retains issues and child epics -----------------------

    #[test]
    fn delete_removes_only_the_registry_entry_and_reports_members_and_children() {
        let (_tmp, store) = store_with(&[("e-1", "Parent"), ("e-2", "Child")], 1);
        write_issue(&store, 1, "Issue 1", &["e-1"]);
        let mut config = store.config.clone();
        config.epics.get_mut("e-2").unwrap().parent = Some("e-1".to_string());
        // The notice names the member and the child and states nothing is deleted.
        let epic = epics::resolve(&config, &store.list_all().unwrap(), "e-1").unwrap();
        let notice = impact_notice(&epic);
        assert!(
            notice.contains("Issue 1"),
            "the notice names the issue: {notice}"
        );
        assert!(
            notice.contains("Child"),
            "the notice names the child: {notice}"
        );
        assert!(notice.contains("not deleted"));

        let issue_before = issue_bytes(&store, 1);
        delete(&mut config, &store, "e-1", true).unwrap();

        // The registry entry is gone; the child epic survives.
        assert!(!config.epics.contains_key("e-1"));
        assert!(config.epics.contains_key("e-2"));
        assert!(!registry(&store).contains("[epics.e-1]"));
        // The issue is untouched: still present, still carrying its reference.
        assert_eq!(issue_bytes(&store, 1), issue_before);
        assert!(issue_bytes(&store, 1).contains("e-1"));
        // The child keeps its recorded parent (now unresolved, C-006).
        assert_eq!(config.epics["e-2"].parent.as_deref(), Some("e-1"));
    }

    #[test]
    fn delete_refuses_an_unknown_id_and_writes_nothing() {
        let (_tmp, store) = store_with(&[("e-1", "A")], 0);
        let mut config = store.config.clone();
        let before = registry(&store);
        let error = delete(&mut config, &store, "bogus", true).expect_err("unknown id");
        assert!(error.to_string().contains("unknown_epic"), "{error}");
        assert!(config.epics.contains_key("e-1"));
        assert_eq!(registry(&store), before);
    }

    // -- T024/T025 — the shared create/edit inputs ---------------------------

    #[test]
    fn resolve_epics_collapses_duplicates_and_refuses_an_unknown_id() {
        let (_tmp, store) = store_with(&[("e-1", "Harden")], 0);
        let ids = resolve_epics(&store.config, "Harden,e-1").unwrap();
        assert_eq!(
            ids,
            vec!["e-1".to_string()],
            "a name and an id are one epic"
        );
        let error = resolve_epics(&store.config, "e-1,bogus").expect_err("unknown id");
        assert!(error.to_string().contains("unknown_epic"), "{error}");
    }

    #[test]
    fn reference_created_writes_one_entry_per_epic() {
        let (_tmp, store) = store_with(&[("e-1", "A"), ("e-2", "B")], 1);
        let issue = store.resolve_issue("1").unwrap();
        reference_created(&store, &issue, &["e-1".to_string(), "e-2".to_string()]).unwrap();
        let after = store.resolve_issue("1").unwrap();
        assert_eq!(
            after.epics,
            Some(vec!["e-1".to_string(), "e-2".to_string()])
        );
        assert_eq!(after.history.events().len(), 2, "one entry per reference");
    }

    #[test]
    fn a_plan_refuses_an_unknown_remove_reference_that_is_not_stored() {
        let (_tmp, store) = store_with(&[("e-1", "A")], 1);
        let error = plan_edit_epics(
            &store.config,
            &store,
            "1",
            &[],
            &["bogus".to_string()],
            false,
        )
        .expect_err("an unresolvable, unstored reference is a typo");
        assert!(error.to_string().contains("unknown_epic"), "{error}");
    }

    #[test]
    fn a_plan_accepts_removing_a_stale_stored_id() {
        let (_tmp, store) = store_with(&[], 1);
        write_issue(&store, 1, "Issue 1", &["e-gone"]);
        let plan = plan_edit_epics(
            &store.config,
            &store,
            "1",
            &[],
            &["e-gone".to_string()],
            false,
        )
        .unwrap();
        assert!(
            apply_edit_epics(&store, "1", &plan).unwrap(),
            "removing a stored id changed the issue"
        );
        assert_eq!(store.resolve_issue("1").unwrap().epics, None);
    }

    #[test]
    fn clearing_removes_every_reference_and_keeps_the_issue() {
        let (_tmp, store) = store_with(&[("e-1", "A"), ("e-2", "B")], 1);
        write_issue(&store, 1, "Issue 1", &["e-1", "e-2"]);
        let plan = plan_edit_epics(&store.config, &store, "1", &[], &[], true).unwrap();
        assert!(apply_edit_epics(&store, "1", &plan).unwrap());
        let issue = store.resolve_issue("1").unwrap();
        assert_eq!(issue.epics, None);
        assert_eq!(issue.history.events().len(), 2, "one entry per removal");
        assert!(
            store.issues_dir.join(&issue.filename).is_file(),
            "the issue itself is kept"
        );
    }

    #[test]
    fn a_noop_epic_plan_reports_no_change() {
        let (_tmp, store) = store_with(&[("e-1", "A"), ("e-2", "B")], 1);
        write_issue(&store, 1, "Issue 1", &["e-1"]);
        // An already-present reference.
        let plan =
            plan_edit_epics(&store.config, &store, "1", &["e-1".to_string()], &[], false).unwrap();
        assert!(
            !apply_edit_epics(&store, "1", &plan).unwrap(),
            "adding an existing reference is a no-op"
        );
        // Removing a reference the registry knows but the issue does not carry is a
        // no-op too.
        let plan =
            plan_edit_epics(&store.config, &store, "1", &[], &["e-2".to_string()], false).unwrap();
        assert!(
            !apply_edit_epics(&store, "1", &plan).unwrap(),
            "removing a reference that is not there is a no-op"
        );
    }

    // -- T026 — association from the epic side and navigation ----------------

    #[test]
    fn bulk_reference_reports_each_selector_independently() {
        let (_tmp, store) = store_with(&[("e-1", "A")], 2);
        let code = reference_from_epic(
            &store.config,
            &store,
            "e-1",
            &["1".to_string(), "99".to_string()],
        )
        .unwrap();
        assert_ne!(code, ExitCode::Success, "a partial batch exits non-zero");
        // The good selector was written and the bad one did not abort it.
        assert!(issue_bytes(&store, 1).contains("e-1"));
        assert_eq!(
            store.resolve_issue("1").unwrap().history.events().len(),
            1,
            "exactly one History entry for the accepted change"
        );
    }

    #[test]
    fn associate_refuses_an_unknown_epic_before_writing_anything() {
        let (_tmp, store) = store_with(&[("e-1", "A")], 1);
        let before = issue_bytes(&store, 1);
        let error = reference_from_epic(&store.config, &store, "bogus", &["1".to_string()])
            .expect_err("an unknown epic refuses up front");
        assert!(error.to_string().contains("unknown_epic"), "{error}");
        assert_eq!(issue_bytes(&store, 1), before, "nothing written");
    }

    #[test]
    fn navigation_lines_are_parent_first_with_ancestors_and_depth() {
        // Chain e-3 -> e-2 -> e-1 (root).
        let (_tmp, store) = store_with(&[("e-1", "Root"), ("e-2", "Mid"), ("e-3", "Leaf")], 0);
        let mut config = store.config.clone();
        config.epics.get_mut("e-2").unwrap().parent = Some("e-1".to_string());
        config.epics.get_mut("e-3").unwrap().parent = Some("e-2".to_string());
        let issues = store.list_all().unwrap();
        let index = epics::EpicIndex::build(&config, &issues);
        let hierarchy = index.hierarchy("e-3").unwrap();
        let epic = index.resolve("e-3").unwrap().clone();
        let lines = navigation_lines(&hierarchy, &epic);
        let pos = |needle: &str| lines.iter().position(|l| l.contains(needle));
        // Parent-first: the ancestor Root precedes the parent Mid, which precedes
        // the epic Leaf.
        assert!(
            pos("Root") < pos("Mid") && pos("Mid") < pos("Leaf"),
            "parent-first order: {lines:?}"
        );
        assert!(lines.contains(&"depth: 2".to_string()), "{lines:?}");
        assert!(
            lines.iter().any(|l| l.contains("navigate one directly")),
            "direct issue navigation is advertised: {lines:?}"
        );
    }

    #[test]
    fn navigation_reports_an_unresolved_parent() {
        let (_tmp, store) = store_with_unresolved_parent();
        let issues = store.list_all().unwrap();
        let index = epics::EpicIndex::build(&store.config, &issues);
        let hierarchy = index.hierarchy("e-1").unwrap();
        let epic = index.resolve("e-1").unwrap().clone();
        let lines = navigation_lines(&hierarchy, &epic);
        assert!(
            lines.iter().any(|l| l.starts_with("unresolved-parent:")),
            "the unresolved parent is reported: {lines:?}"
        );
        assert!(lines.contains(&"parent: -".to_string()), "{lines:?}");
    }

    #[test]
    fn impact_notice_agrees_with_its_subject() {
        // One member and one child epic: singular verbs, "its parent".
        let (_tmp, store) = store_with(&[("e-1", "Parent"), ("e-2", "Child")], 1);
        write_issue(&store, 1, "Issue 1", &["e-1"]);
        let mut config = store.config.clone();
        config.epics.get_mut("e-2").unwrap().parent = Some("e-1".to_string());
        let epic = epics::resolve(&config, &store.list_all().unwrap(), "e-1").unwrap();
        let notice = impact_notice(&epic);
        assert!(
            notice.contains("1 issue still references this epic"),
            "{notice}"
        );
        assert!(
            notice.contains("1 child epic records this epic as its parent"),
            "{notice}"
        );

        // Two members and two children: plural verbs.
        let (_tmp2, store2) = store_with(
            &[("e-1", "Parent"), ("e-2", "Child A"), ("e-3", "Child B")],
            2,
        );
        write_issue(&store2, 1, "Issue 1", &["e-1"]);
        write_issue(&store2, 2, "Issue 2", &["e-1"]);
        let mut config2 = store2.config.clone();
        config2.epics.get_mut("e-2").unwrap().parent = Some("e-1".to_string());
        config2.epics.get_mut("e-3").unwrap().parent = Some("e-1".to_string());
        let epic2 = epics::resolve(&config2, &store2.list_all().unwrap(), "e-1").unwrap();
        let notice2 = impact_notice(&epic2);
        assert!(
            notice2.contains("2 issues still reference this epic"),
            "{notice2}"
        );
        assert!(
            notice2.contains("2 child epics record this epic as their parent"),
            "{notice2}"
        );
    }
}