amont_agent_process/

implementation_review.rs

//! The implementation review (ADR-0022, `work.implementation-review`):
//! before the push of a branch that carries a plan, one independent
//! reviewer has read the diff against the plan and the active rules, and
//! its verdict is bound to the tree it read.
//!
//! A review is bound to the **content id** of the commit it read (attest
//! SPEC, "Content id"; not attest's canonical tree, which counts whether a
//! plan exists): the sha256 of `git ls-tree -r -z --full-tree <rev>`'s entries — mode,
//! type, object id and path, in git's own order — with every entry under
//! `docs/plans/` left out. So recording the review in the plan never makes
//! it stale, a later code change does, and the id is 64 hex whatever the
//! repository's object format. It is computed read-only: no index, no
//! object written, nothing to clean up if the hook is killed.
//!
//! The repository in a block is named by the basename of the parent of
//! `git rev-parse --git-common-dir`, so a worktree checked out as
//! `amont-agent-wt-x` still says `amont-agent`, and `tree-sha` and the
//! rule cannot disagree on the name.
//!
//! ## What the hook reads
//!
//! A push is judged by `confirm` (the rule is `rules::implementation_review`):
//! the pushed commit, the base it grew from (the remote's default branch,
//! never the branch's own tracking ref — once a branch is published its
//! plan commit is on the remote too, and a later push compared to the
//! tracking ref would show no `docs/plans/` change and skip the rule for
//! good), whether `docs/plans/` changed since that base, the content id,
//! and then a binding: a completed `implementation-review` agent in this
//! session's transcript whose block names this repository and tree, or a
//! pass remembered under `<state>/implementation-review/by-tree/`.
//!
//! A pass also holds for another tree with the same **branch patch** when
//! the repository's rule files are unchanged (ADR-0034,
//! `work.implementation-review-binding`): a conflict-free rebase onto a
//! moved `main` changes the tree, not the diff the reviewer read. The patch
//! is `git diff --binary <merge-base> <pushed> -- . ':!docs/plans'` hashed by
//! `git patch-id --verbatim`; the rules are `AGENTS.md`, `CLAUDE.md`,
//! `.adr.yaml`, `.adr/` and `.claude/` in the pushed tree. A pass is filed
//! under `by-patch/` too, and a hit there is journalled `reviewed-by-patch`.
//!
//! The verdict is read, not assumed: a review that said `rework` and got
//! no later delta on the same tree is not a pass. Only the hook writes a
//! pass file — from a transcript binding, or from the person's `Overrule`
//! on a marked question — and a Bash, Write or Edit under that directory
//! is refused by the hook itself, outside any stance, because under `deny`
//! a pass file is a trust boundary.

use std::path::{Component, Path, PathBuf};

use crate::content_id::content_id;
use crate::plan_review::{completed_agents_resumable, Completed};
use crate::provenance::Review as Bound;
use amont_agent_guard::git;
use amont_agent_guard::journal;
use amont_agent_guard::rules::{Confirmed, Context, Stance};
use amont_agent_guard::sha256::{hex, sha256};
use amont_agent_guard::shell::Simple;

pub const RULE_ID: &str = "implementation-review";
/// The agent type the reviewer is launched as; a prefix, like the panel's.
const AGENT: &str = "implementation-review";
/// Opens a review block in the reviewer's prompt.
pub const BLOCK_OPEN: &str = "<<<TREE ";
const BLOCK_CLOSE: &str = ">>>";
/// The directory a review does not bind to: the plan's own record.
const PLANS_PATH: &str = "docs/plans";
/// The marker a person's overrule question carries.
const MARKER: &str = "[implementation-review ";
const OVERRULE: &str = "Overrule";

// ---------------------------------------------------------------- the tree

/// The files whose content a review was read against, besides the diff:
/// the repository's active rules.
const RULE_FILES: &[&[u8]] = &[b"AGENTS.md", b"CLAUDE.md", b".adr.yaml"];
const RULE_DIRS: &[&[u8]] = &[b".adr/", b".claude/"];

/// What a pass carries over to another tree: the branch patch and the
/// fingerprint of the rule files. Both must match.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct PatchKey {
    pub patch: String,
    pub rules: String,
}

/// The `git patch-id --verbatim` of the branch's diff since `merge_base`,
/// `docs/plans/` left out. `Err` on an empty diff or any failure: a key
/// that cannot be computed carries nothing over.
pub fn branch_patch(repo: &Path, merge_base: &str, pushed: &str) -> Result<String, String> {
    let diff = git::bytes_in(
        repo,
        &[
            "diff",
            "--binary",
            "--no-ext-diff",
            "--no-textconv",
            "--no-color",
            merge_base,
            pushed,
            "--",
            ".",
            &format!(":!{PLANS_PATH}"),
        ],
        None,
    )
    .map_err(|e| format!("git could not be run: {e}"))?
    .ok_or("`git diff` against the base failed")?;
    if diff.is_empty() {
        return Err("the branch changes nothing outside docs/plans/".into());
    }
    let out = git::bytes_in(repo, &["patch-id", "--verbatim"], Some(&diff))
        .map_err(|e| format!("git could not be run: {e}"))?
        .ok_or("`git patch-id` failed")?;
    let out = String::from_utf8_lossy(&out);
    out.split_whitespace()
        .next()
        .filter(|id| !id.is_empty() && id.bytes().all(|b| b.is_ascii_hexdigit()))
        .map(str::to_string)
        .ok_or_else(|| "`git patch-id` printed no id".into())
}

/// The sha256 of the rule files' entries in `rev`'s tree.
pub fn rules_fingerprint(repo: &Path, rev: &str) -> Result<String, String> {
    let spec = format!("{rev}^{{tree}}");
    let entries = git::ls_tree_entries(repo, &spec)
        .map_err(|e| format!("git could not be run in {}: {e}", repo.display()))?
        .ok_or_else(|| format!("`{rev}` does not name a tree in {}", repo.display()))?;
    let mut bytes: Vec<u8> = Vec::new();
    for entry in entries {
        let path = entry
            .iter()
            .position(|c| *c == b'\t')
            .map(|i| &entry[i + 1..])
            .unwrap_or(&entry[..]);
        if RULE_FILES.contains(&path) || RULE_DIRS.iter().any(|d| path.starts_with(d)) {
            bytes.extend_from_slice(&entry);
            bytes.push(0);
        }
    }
    Ok(hex(&sha256(&bytes)))
}

/// Both halves of the key for `pushed`, or why either cannot be computed:
/// a miss, never a pass, and the caller says the reason when it holds.
pub fn patch_key(repo: &Path, merge_base: &str, pushed: &str) -> Result<PatchKey, String> {
    Ok(PatchKey {
        patch: branch_patch(repo, merge_base, pushed)?,
        rules: rules_fingerprint(repo, pushed)?,
    })
}

/// The repository's name for a block: the basename of the directory that
/// holds its common `.git`, whichever worktree `repo` is.
pub fn repo_name(repo: &Path) -> Option<String> {
    let common = git::stdout_in(repo, &["rev-parse", "--git-common-dir"])?;
    if common.is_empty() {
        return None;
    }
    let common = PathBuf::from(common);
    let common = if common.is_absolute() {
        common
    } else {
        repo.join(common)
    };
    let common = std::fs::canonicalize(&common).unwrap_or(common);
    common
        .parent()
        .and_then(Path::file_name)
        .map(|n| n.to_string_lossy().into_owned())
        .filter(|n| !n.is_empty())
}

/// The review block a reviewer's prompt carries.
pub fn block(repo: &str, sha: &str) -> String {
    format!("{BLOCK_OPEN}repo={repo} sha={sha}{BLOCK_CLOSE}")
}

/// The `(repo, sha)` of every review block in a prompt. A sha that is not
/// 64 hex is not a binding.
pub fn parse_blocks(prompt: &str) -> Vec<(String, String)> {
    let mut out = Vec::new();
    let mut rest = prompt;
    while let Some(at) = rest.find(BLOCK_OPEN) {
        rest = &rest[at + BLOCK_OPEN.len()..];
        let Some(end) = rest.find(BLOCK_CLOSE) else {
            break;
        };
        let inner = &rest[..end];
        rest = &rest[end..];
        let Some(body) = inner.strip_prefix("repo=") else {
            continue;
        };
        let Some(split) = body.rfind(" sha=") else {
            continue;
        };
        let repo = body[..split].trim().to_string();
        let sha = body[split + 5..].trim().to_ascii_lowercase();
        if repo.is_empty() || !is_sha256(&sha) {
            continue;
        }
        out.push((repo, sha));
    }
    out
}

pub fn is_sha256(s: &str) -> bool {
    s.len() == 64 && s.bytes().all(|b| b.is_ascii_hexdigit())
}

fn short(sha: &str) -> &str {
    &sha[..sha.len().min(12)]
}

// ---------------------------------------------------------------- the verdict

/// What a reviewer's result said, read from its first `Verdict:` line.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum Verdict {
    Approve,
    ApproveWithChanges,
    Rework,
}

impl Verdict {
    pub fn as_str(self) -> &'static str {
        match self {
            Verdict::Approve => "approve",
            Verdict::ApproveWithChanges => "approve-with-changes",
            Verdict::Rework => "rework",
        }
    }
}

/// The verdict a result text states, or `None` when it states none the
/// contract knows — which is not a pass.
pub fn verdict_of(result: &str) -> Option<Verdict> {
    let line = result.lines().find(|l| l.contains("Verdict:"))?;
    let after = line.split_once("Verdict:")?.1;
    let word: String = after
        .trim()
        .trim_start_matches(['*', '`', '_', ' '])
        .chars()
        .take_while(|c| c.is_ascii_alphanumeric() || *c == '-')
        .collect::<String>()
        .to_ascii_lowercase();
    match word.as_str() {
        "approve-with-changes" => Some(Verdict::ApproveWithChanges),
        "approve" | "approved" => Some(Verdict::Approve),
        "rework" => Some(Verdict::Rework),
        _ => None,
    }
}

/// The reviews this session completed, in launch order: what each bound
/// and what it said. A reviewer resumed with `SendMessage` on a new block is
/// a review of its own ([`completed_agents_resumable`]).
pub struct Review {
    pub repo: String,
    pub sha: String,
    pub verdict: Option<Verdict>,
    /// The sha of the prompt's `<<<RULES …>>>` line, when it has a valid one.
    pub rules_sha: Option<String>,
}

pub fn reviews(transcript: &Path) -> std::io::Result<Vec<Review>> {
    let file = std::fs::File::open(transcript)?;
    let reader = std::io::BufReader::new(file);
    Ok(completed_agents_resumable(reader, AGENT)
        .into_iter()
        .flat_map(|c: Completed| {
            let verdict = verdict_of(&c.result);
            let rules_sha = crate::review_brief::parse_rules_sha(&c.prompt);
            parse_blocks(&c.prompt)
                .into_iter()
                .map(move |(repo, sha)| Review {
                    repo,
                    sha,
                    verdict,
                    rules_sha: rules_sha.clone(),
                })
        })
        .collect())
}

// ---------------------------------------------------------------- the store

fn store() -> Option<PathBuf> {
    Some(journal::dir()?.join(RULE_ID))
}

fn private_dir(dir: &Path) -> Option<()> {
    std::fs::create_dir_all(dir).ok()?;
    journal::private(dir, 0o700);
    Some(())
}

fn pass_file(repo: &str, sha: &str) -> Option<PathBuf> {
    if repo.contains('/') || repo.contains("..") || !is_sha256(sha) {
        return None;
    }
    Some(
        store()?
            .join("by-tree")
            .join(repo)
            .join(format!("{sha}.json")),
    )
}

/// The verdict a remembered pass carries (`approve`, `approve-with-changes`
/// or `overruled`), if this repository and tree have one.
pub fn remembered(repo: &str, sha: &str) -> Option<String> {
    remembered_pass(repo, sha).map(|pass| pass.verdict)
}

/// A remembered verdict and the rules line the passing review's prompt
/// carried.
struct Pass {
    verdict: String,
    prompt_rules: PromptRules,
}

/// What a passing review's prompt said about the rules it was given.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum PromptRules {
    /// The pass was remembered before the rules line was stored.
    NotRecorded,
    /// The prompt carried no rules line.
    Absent,
    /// The prompt's rules line, 64 hex.
    Sha(String),
}

/// How [`PromptRules::Absent`] is stored: the field is kept, and empty, so
/// it reads apart from a pass that predates the field.
const RULES_ABSENT_STORED: &str = "";

impl PromptRules {
    fn of_prompt(sha: Option<&str>) -> PromptRules {
        sha.map_or(PromptRules::Absent, |sha| PromptRules::Sha(sha.to_string()))
    }

    /// The stored `prompt_rules_sha`: `null` (not recorded), `""` (absent)
    /// or the sha.
    fn stored(&self) -> Option<&str> {
        match self {
            PromptRules::NotRecorded => None,
            PromptRules::Absent => Some(RULES_ABSENT_STORED),
            PromptRules::Sha(sha) => Some(sha),
        }
    }

    fn from_stored(stored: Option<&str>) -> PromptRules {
        match stored {
            None => PromptRules::NotRecorded,
            Some(RULES_ABSENT_STORED) => PromptRules::Absent,
            Some(sha) => PromptRules::Sha(sha.to_string()),
        }
    }
}

fn pass_of(stored_record: &serde_json::Value) -> Option<Pass> {
    Some(Pass {
        verdict: stored_record.get("verdict")?.as_str()?.to_string(),
        prompt_rules: PromptRules::from_stored(
            stored_record
                .get("prompt_rules_sha")
                .and_then(serde_json::Value::as_str),
        ),
    })
}

fn remembered_pass(repo: &str, sha: &str) -> Option<Pass> {
    let f = pass_file(repo, sha)?;
    pass_of(&serde_json::from_str(&std::fs::read_to_string(f).ok()?).ok()?)
}

/// Written only by the hook: from a transcript binding whose verdict is a
/// pass, or from the person's `Overrule` of a `rework`.
fn remember(
    repo: &str,
    sha: &str,
    verdict: &str,
    how: &str,
    prompt_rules: &PromptRules,
) -> Option<()> {
    let f = pass_file(repo, sha)?;
    private_dir(f.parent()?)?;
    let body = serde_json::json!({
        "repo": repo,
        "tree": sha,
        "verdict": verdict,
        "agent": AGENT,
        "how": how,
        "prompt_rules_sha": prompt_rules.stored(),
    })
    .to_string();
    amont_agent_guard::atomic::write_atomic(&f, &body).ok()?;
    journal::private(&f, 0o600);
    Some(())
}

fn patch_file(repo: &str, patch: &str) -> Option<PathBuf> {
    if repo.contains('/')
        || repo.contains("..")
        || patch.is_empty()
        || !patch.bytes().all(|b| b.is_ascii_hexdigit())
    {
        return None;
    }
    Some(
        store()?
            .join("by-patch")
            .join(repo)
            .join(format!("{patch}.json")),
    )
}

/// The pass remembered for this patch, when its rules match: the verdict
/// and the tree it was given for.
fn remembered_patch(repo: &str, key: &PatchKey) -> Option<(Pass, String)> {
    let f = patch_file(repo, &key.patch)?;
    let v: serde_json::Value = serde_json::from_str(&std::fs::read_to_string(f).ok()?).ok()?;
    if v.get("rules")?.as_str()? != key.rules {
        return None;
    }
    Some((pass_of(&v)?, v.get("tree")?.as_str()?.to_string()))
}

/// Files a pass under its patch too, so a conflict-free rebase keeps it.
fn remember_patch(
    repo: &str,
    key: &PatchKey,
    tree: &str,
    verdict: &str,
    how: &str,
    prompt_rules: &PromptRules,
) -> Option<()> {
    let f = patch_file(repo, &key.patch)?;
    private_dir(f.parent()?)?;
    let body = serde_json::json!({
        "repo": repo,
        "patch": key.patch,
        "rules": key.rules,
        "tree": tree,
        "verdict": verdict,
        "agent": AGENT,
        "how": how,
        "prompt_rules_sha": prompt_rules.stored(),
    })
    .to_string();
    amont_agent_guard::atomic::write_atomic(&f, &body).ok()?;
    journal::private(&f, 0o600);
    Some(())
}

// ---------------------------------------------------------------- the push

/// What the hook found out about a push.
pub enum Judged {
    /// The rule has nothing to say: the reason is the journal's
    /// `unconfirmed` reason.
    Decline(&'static str),
    /// The rule speaks: the reason to say, and the journal excerpt.
    Say { reason: String, excerpt: String },
}

/// Judge the push in `cmd`, whose clause runs in `cwd`.
pub fn judge_push(ctx: &Context, cmd: &Simple, stance: Stance) -> Judged {
    use amont_agent_guard::push_target::{self, Kind, Push};
    let (repo, targets) = match push_target::resolve_for(ctx, cmd) {
        Push::Resolved { repo, targets } => (repo, targets),
        Push::DryRun => return Judged::Decline("dry-run"),
        Push::DeleteOnly => return Judged::Decline("delete-only"),
        // amont refuses this land itself: nothing is published.
        Push::Refused(_) => return Judged::Decline("land-refused"),
        Push::Unresolvable { shape, .. } => {
            // Under `deny` an unreadable shape is held, so `--all` is not the
            // way around the gate; otherwise it is journalled and passes.
            return if stance == Stance::Deny {
                unknown(None, &format!("the push cannot be read: {shape}"))
            } else {
                Judged::Decline("unresolvable")
            };
        }
    };
    let Some(target) = targets.iter().find(|t| t.kind == Kind::Branch) else {
        return Judged::Decline("no-branch");
    };
    let pushed = target.src.as_str();
    // Commits some remote already has are not this push's work: seeding a
    // fork reaches here with no default branch on the fork, and used to ask
    // for a review of upstream's history.
    if git::nothing_new(&repo, pushed) {
        return Judged::Decline("nothing-new");
    }
    let Some(base) = default_base(&repo, &target.remote) else {
        return unknown(
            None,
            &format!(
                "no default branch of `{}` is known here (no {0}/HEAD, {0}/main or {0}/master)",
                target.remote
            ),
        );
    };
    let Some(merge_base) = git::stdout_in(&repo, &["merge-base", pushed, &base]) else {
        return unknown(
            None,
            &format!("`git merge-base {} {base}` failed", short(pushed)),
        );
    };
    let Some(changed) = git::stdout_in(
        &repo,
        &["diff", "--name-only", &merge_base, pushed, "--", PLANS_PATH],
    ) else {
        return unknown(None, "`git diff` against the base failed");
    };
    if changed.trim().is_empty() {
        return Judged::Decline("no-plan");
    }
    let tree = match content_id(&repo, pushed) {
        Ok(t) => t,
        Err(why) => return unknown(None, &why),
    };
    let Some(name) = repo_name(&repo) else {
        return unknown(Some(&tree), "the repository has no name");
    };
    // The branch patch, computed once: a pass found here or below is filed
    // under it, and a miss by tree is looked up by it.
    let key = patch_key(&repo, &merge_base, pushed);
    let plans: Vec<String> = changed
        .lines()
        .map(str::trim)
        .filter(|l| !l.is_empty())
        .map(str::to_string)
        .collect();
    // Said when the push is held: no earlier review could carry over.
    let unkeyed = key
        .as_ref()
        .err()
        .map(|why| format!(" No earlier review could carry over by patch: {why}."))
        .unwrap_or_default();
    let key = key.ok();
    let push = crate::provenance::Push {
        repo: &repo,
        name: &name,
        pushed,
        patch: key.as_ref().map(|k| k.patch.as_str()),
        plans: &plans,
        target,
    };
    if let Some(Pass {
        verdict,
        prompt_rules,
    }) = remembered_pass(&name, &tree)
    {
        if let Some(k) = &key {
            if remembered_patch(&name, k).is_none() {
                remember_patch(&name, k, &tree, &verdict, "tree", &prompt_rules);
            }
        }
        let overruled = verdict == "overruled";
        provenance(
            &push,
            if overruled {
                Bound::Overruled
            } else {
                Bound::Reviewed
            },
            &tree,
        );
        if !overruled {
            check_remembered_rules(&repo, &name, &tree, &prompt_rules);
        }
        return Judged::Decline(if overruled { "overruled" } else { "reviewed" });
    }
    if let Some((pass, old_tree)) = key.as_ref().and_then(|k| remembered_patch(&name, k)) {
        let Pass {
            verdict,
            prompt_rules,
        } = pass;
        remember(
            &name,
            &tree,
            &verdict,
            &format!("patch {}", short(&old_tree)),
            &prompt_rules,
        );
        let overruled = verdict == "overruled";
        provenance(
            &push,
            if overruled {
                Bound::Overruled
            } else {
                Bound::ByPatch
            },
            &old_tree,
        );
        if !overruled {
            check_remembered_rules(&repo, &name, &tree, &prompt_rules);
        }
        return Judged::Decline(if overruled {
            "overruled-by-patch"
        } else {
            "reviewed-by-patch"
        });
    }
    let Some(transcript) = ctx.transcript else {
        return unknown(Some(&tree), "the payload carried no transcript_path");
    };
    let reviews = match reviews(transcript) {
        Ok(r) => r,
        Err(e) => {
            return unknown(
                Some(&tree),
                &format!(
                    "the transcript {} could not be read: {e}",
                    transcript.display()
                ),
            )
        }
    };
    let mine: Vec<&Review> = reviews.iter().filter(|r| r.repo == name).collect();
    if let Some(latest) = mine.iter().rev().find(|r| r.sha == tree) {
        return match latest.verdict {
            Some(Verdict::Rework) | None => Judged::Say {
                reason: format!(
                    "the implementation review of {name} tree {} said {}, and no delta followed.",
                    short(&tree),
                    latest
                        .verdict
                        .map(Verdict::as_str)
                        .unwrap_or("no verdict this guard can read")
                ),
                excerpt: format!(
                    "tree={} review=rework verdict={}",
                    short(&tree),
                    latest.verdict.map(Verdict::as_str).unwrap_or("-")
                ),
            },
            Some(v) => {
                let prompt_rules = PromptRules::of_prompt(latest.rules_sha.as_deref());
                remember(&name, &tree, v.as_str(), "transcript", &prompt_rules);
                if let Some(k) = &key {
                    remember_patch(&name, k, &tree, v.as_str(), "transcript", &prompt_rules);
                }
                provenance(&push, Bound::Reviewed, &tree);
                check_remembered_rules(&repo, &name, &tree, &prompt_rules);
                Judged::Decline("reviewed")
            }
        };
    }
    if let Some(older) = mine.last() {
        return Judged::Say {
            reason: format!(
                "the implementation review of {name} read tree {}; this push carries tree {} (stale).{unkeyed}",
                short(&older.sha),
                short(&tree)
            ),
            excerpt: format!("tree={} review=stale verdict=-", short(&tree)),
        };
    }
    Judged::Say {
        reason: format!(
            "no implementation review of {name} tree {} is in this session.{unkeyed}",
            short(&tree)
        ),
        excerpt: format!("tree={} review=missing verdict=-", short(&tree)),
    }
}

/// The advise-only comparison of the rules a passing review read with the
/// rules now: journalled, never holding the push. `prompt_rules` is what the
/// pass remembered: `NotRecorded` (from before the line was stored) journals
/// `rules-unknown`; `Absent` and `Sha` are compared with `rules_sha` now.
fn check_remembered_rules(repo: &Path, name: &str, tree: &str, prompt_rules: &PromptRules) {
    let excerpt = match prompt_rules {
        PromptRules::NotRecorded => "review=rules-unknown",
        PromptRules::Absent => {
            crate::review_brief::rules_excerpt(None, &crate::review_brief::rules_sha(repo))
        }
        PromptRules::Sha(seen) => {
            crate::review_brief::rules_excerpt(Some(seen), &crate::review_brief::rules_sha(repo))
        }
    };
    note(
        "rules-checked",
        "-",
        name,
        &format!("tree={} {excerpt}", short(tree)),
    );
}

/// Files the provenance record of a pass and journals what came of it. A
/// failure never changes the judgment.
fn provenance(push: &crate::provenance::Push, review: Bound, review_content: &str) {
    use crate::provenance::Filing;
    match crate::provenance::file(push, review, review_content) {
        Filing::Deferred => note(
            "provenance-deferred",
            "-",
            push.name,
            "the preview has not stood",
        ),
        Filing::Written(file) => note(
            "provenance-written",
            "-",
            push.name,
            &file.display().to_string(),
        ),
        Filing::Kept(file) => note(
            "provenance-kept",
            "-",
            push.name,
            &file.display().to_string(),
        ),
        Filing::Failed(why) => note("provenance-write-failed", "-", push.name, &why),
    }
}

fn unknown(tree: Option<&str>, why: &str) -> Judged {
    Judged::Say {
        reason: format!("whether this push was reviewed cannot be told: {why}"),
        excerpt: format!(
            "tree={} review=unknown verdict=-",
            tree.map(short).unwrap_or("-")
        ),
    }
}

/// The remote's default branch as last fetched: `<remote>/HEAD`, else
/// `<remote>/main`, else `<remote>/master`. Never `HEAD`: with the pushed
/// commit as its own base every push would show no plan.
pub(crate) fn default_base(repo: &Path, remote: &str) -> Option<String> {
    [
        format!("refs/remotes/{remote}/HEAD"),
        format!("refs/remotes/{remote}/main"),
        format!("refs/remotes/{remote}/master"),
    ]
    .into_iter()
    .find(|r| {
        git::stdout_in(
            repo,
            &[
                "rev-parse",
                "--verify",
                "--quiet",
                "--end-of-options",
                &format!("{r}^{{commit}}"),
            ],
        )
        .is_some_and(|s| !s.is_empty())
    })
}

/// The rule's `confirm`, for a push: what to say, or why not.
pub fn confirm_push(ctx: &Context, cmd: &Simple, stance: Stance) -> Confirmed {
    match judge_push(ctx, cmd, stance) {
        Judged::Decline(why) => Confirmed::No(why),
        Judged::Say { reason, excerpt } => Confirmed::YesSaying {
            remedy: None,
            floor: None,
            ceiling: None,
            reason,
            excerpt,
        },
    }
}

// ---------------------------------------------------------------- the guards

/// Whether a path is inside the pass-file store, compared lexically (`.`
/// and `..` folded, no symlink followed) and, where the store exists, by
/// its canonical form too. Only the hook writes there.
pub fn guards_path(path: &Path) -> bool {
    HOOK_ONLY_DIRS
        .iter()
        .filter_map(|d| Some(journal::dir()?.join(d)))
        .any(|store| guards_store(path, &store))
}

fn guards_store(path: &Path, store: &Path) -> bool {
    let here = lexical(path);
    if here.starts_with(lexical(store)) {
        return true;
    }
    if let Ok(real) = std::fs::canonicalize(store) {
        if here.starts_with(&real) {
            return true;
        }
        // The path's own existing ancestor, resolved.
        if let Some(parent) = here.parent() {
            if let Ok(real_parent) = std::fs::canonicalize(parent) {
                return real_parent.starts_with(&real);
            }
        }
    }
    false
}

/// A path with `.` and `..` folded lexically.
pub fn lexical(path: &Path) -> PathBuf {
    let mut out = PathBuf::new();
    for c in path.components() {
        match c {
            Component::CurDir => {}
            Component::ParentDir => {
                out.pop();
            }
            other => out.push(other.as_os_str()),
        }
    }
    out
}

/// Programs whose operand naming the store is taken as a write. A reader
/// (`ls`, `cat`, `find`, `grep`, `stat`, …) is not on this list, so looking
/// at the record is allowed; the list is the Bash half of a best-effort
/// guard, since a parser cannot see inside `python -c` beyond its words.
const WRITERS: &[&str] = &[
    "rm", "mv", "cp", "tee", "touch", "install", "truncate", "ln", "chmod", "chown", "mkdir",
    "rmdir", "dd", "sed", "perl", "ruby", "node", "deno", "python", "python3", "sh", "bash", "zsh",
    "dash", "fish", "sudo", "xargs", "rsync", "tar", "unzip", "chezmoi", "git",
];

/// The first clause of a command that would WRITE into the store: a redirect
/// into it (`> …/by-tree/…`), or a program on [`WRITERS`] with a word naming
/// it. A read — `ls`, `cat`, `find` of the pass files — passes: the record is
/// there to be looked at. Returns the clause's span.
pub fn store_clause(parsed: &amont_agent_guard::shell::Parsed) -> Option<std::ops::Range<usize>> {
    parsed
        .clauses()
        .iter()
        .find(|cmd| {
            let redirected = cmd
                .redirects
                .iter()
                .any(|(op, w)| op.contains('>') && names_store(&w.text));
            let writer = cmd
                .program()
                .map(|p| p.rsplit('/').next().unwrap_or(p))
                .is_some_and(|p| WRITERS.contains(&p) || p.starts_with("python"));
            redirected || (writer && cmd.words.iter().any(|w| names_store(&w.text)))
        })
        .map(|cmd| cmd.at..cmd.end)
}

/// Whether a shell word names the store, spelled with either separator:
/// Windows writes the same directory with backslashes.
pub fn names_store(word: &str) -> bool {
    let word = word.replace('\\', "/");
    HOOK_ONLY_DIRS.iter().any(|d| {
        word.contains(&format!("amont-agent/{d}/"))
            || word.contains(&format!("amont-agent/{d}")) && word.ends_with(d)
    })
}

/// The directories under the config dir that only the hook writes.
const HOOK_ONLY_DIRS: &[&str] = &[RULE_ID, "provenance"];

pub const GUARD_REASON: &str =
    "files under amont-agent/implementation-review/ and amont-agent/provenance/ are written by the hook alone: the pass files from a completed review in this session's transcript or the person's Overrule, the provenance records from a push the hook passed.";
pub const GUARD_REMEDY: &str =
    "Run the review (worktree-task F4b) or ask the person; never write the record by hand.";

// ---------------------------------------------------------------- the person

/// The `(repo, sha)` a marked question names:
/// `[implementation-review <repo>@<sha64>]`, split at the last `@`.
pub fn marker(question: &str) -> Option<(String, String)> {
    let start = question.find(MARKER)? + MARKER.len();
    let end = start + question[start..].find(']')?;
    let inner = question[start..end].trim();
    let at = inner.rfind('@')?;
    let repo = inner[..at].trim().to_string();
    let sha = inner[at + 1..].trim().to_ascii_lowercase();
    (!repo.is_empty() && is_sha256(&sha)).then_some((repo, sha))
}

fn asks_dir() -> Option<PathBuf> {
    Some(store()?.join("asks"))
}

fn now_ms() -> u64 {
    std::time::SystemTime::now()
        .duration_since(std::time::UNIX_EPOCH)
        .map(|d| d.as_millis() as u64)
        .unwrap_or(0)
}

/// Before an `AskUserQuestion` runs: remember a marked question, and whether
/// it arrived pre-answered, so the answer can be trusted or not.
pub fn on_pre_ask(ask: &amont_agent_guard::payload::Ask) {
    let marked: Vec<(String, String)> = ask.questions.iter().filter_map(|q| marker(q)).collect();
    if marked.is_empty() || ask.tool_use_id.is_empty() || ask.tool_use_id.contains('/') {
        return;
    }
    let Some(d) = asks_dir() else { return };
    if private_dir(&d).is_none() {
        return;
    }
    let names: Vec<String> = marked.iter().map(|(r, s)| format!("{r}@{s}")).collect();
    let _ = amont_agent_guard::atomic::write_atomic(
        &d.join(&ask.tool_use_id),
        &format!(
            "{}\t{}\t{}\t{}\n",
            ask.session.replace(['\t', '\n'], " "),
            ask.prefilled,
            names.join(","),
            now_ms()
        ),
    );
    if ask.prefilled {
        note("prefilled", &ask.session, &marked[0].0, &names.join(","));
    }
}

/// After an `AskUserQuestion`: an `Overrule` of a `rework` this session's
/// transcript shows is remembered as a pass; anything else changes nothing.
/// Returns what the session must hear when an overrule bound nothing.
pub fn on_post_ask(ask: &amont_agent_guard::payload::Ask) -> Option<String> {
    if !ask.questions.iter().any(|q| marker(q).is_some()) {
        return None;
    }
    let recorded = asks_dir()
        .map(|d| d.join(&ask.tool_use_id))
        .filter(|_| !ask.tool_use_id.is_empty() && !ask.tool_use_id.contains('/'))
        .and_then(|p| {
            let t = std::fs::read_to_string(&p).ok();
            let _ = std::fs::remove_file(&p);
            t
        });
    let Some(recorded) = recorded else {
        note(
            "unrecorded",
            &ask.session,
            "-",
            "marked question with no PreToolUse record",
        );
        return None;
    };
    let f: Vec<&str> = recorded.trim_end().split('\t').collect();
    if f.len() != 4 || f[0] != ask.session || f[1] != "false" {
        return None;
    }
    let mut said: Vec<String> = Vec::new();
    for question in &ask.questions {
        let Some((repo, sha)) = marker(question) else {
            continue;
        };
        let label = ask
            .answers
            .iter()
            .find(|(q, _)| q == question)
            .map(|(_, l)| l.as_str())
            .unwrap_or("");
        if label != OVERRULE {
            if !label.is_empty() {
                note(
                    "answered",
                    &ask.session,
                    &repo,
                    &format!("tree={} answer={}", short(&sha), label.to_ascii_lowercase()),
                );
            }
            continue;
        }
        let Some(transcript) = ask.transcript.as_deref() else {
            note(
                "unknown",
                &ask.session,
                &repo,
                &format!("tree={} overrule without a transcript", short(&sha)),
            );
            said.push(format!(
                "The answer Overrule bound NOTHING for {repo} tree {}: the question's event carried no transcript, so the rework it overrules cannot be seen.",
                short(&sha)
            ));
            continue;
        };
        let reworked = reviews(transcript)
            .map(|rs| {
                rs.iter()
                    .rev()
                    .find(|r| r.repo == repo && r.sha == sha)
                    .is_some_and(|r| matches!(r.verdict, Some(Verdict::Rework) | None))
            })
            .unwrap_or(false);
        if !reworked {
            note(
                "unbound",
                &ask.session,
                &repo,
                &format!("tree={} overrule with no rework to overrule", short(&sha)),
            );
            said.push(format!(
                "The answer Overrule bound NOTHING for {repo} tree {}: no completed implementation review of that tree said rework in this session.",
                short(&sha)
            ));
            continue;
        }
        remember(
            &repo,
            &sha,
            "overruled",
            "person",
            &PromptRules::NotRecorded,
        );
        note(
            "overruled",
            &ask.session,
            &repo,
            &format!("tree={} review=overruled verdict=rework", short(&sha)),
        );
    }
    (!said.is_empty()).then(|| said.join("\n\n"))
}

/// One journal line under the rule's id, for what happens away from a push.
fn note(outcome: &str, session: &str, repo: &str, excerpt: &str) {
    journal::record(&journal::Entry {
        rule: RULE_ID,
        stance: "-",
        outcome,
        session,
        repo,
        mode: "-",
        excerpt,
    });
}

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

    /// A real session's launch of an implementation reviewer, resumed twice
    /// with `SendMessage` (2026-10-08), anonymised.
    const RESUMED: &str = include_str!("../../../tests/fixtures/sendmessage-resume.jsonl");
    const LAUNCH_TREE: &str = "6066ad987edfbbb3a514b6d9247b126a77a316db2e1350c226ffd14593a0ba35";
    const ROUND_2: &str = "b196a592b3b76cb75155b14491291a45602ae66c6f20ef18e4413a34169556ab";
    const ROUND_3: &str = "85f71e67db10c7737c55b27a3c5753b2617c58dec0d58e7ebae5085898cc12d7";

    /// The known answers attest's SPEC quotes under "Content id". Changing
    /// one is changing the definition: every stored review and approval
    /// would stop matching.
    #[test]
    fn the_content_id_gives_the_spec_known_answers() {
        let o1 = "1".repeat(40);
        let o2 = "2".repeat(40);
        let id = |recs: &[String]| {
            content_id_of(
                &recs
                    .iter()
                    .map(|r| r.as_bytes().to_vec())
                    .collect::<Vec<_>>(),
            )
        };
        // no records: the sha256 of the empty string
        assert_eq!(
            id(&[]),
            "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
        );
        assert_eq!(
            id(&[format!("100644 blob {o1}\tREADME.md")]),
            "6f0214fffd79cb8eb5afb2283e46911f5f9022a25b3f339ae8a50a1ee223a0b2"
        );
        // every record under the top-level docs/plans/ is left out, a
        // symlink too; a near name and a nested docs/plans/ are kept
        let several = [
            format!("100644 blob {o1}\tREADME.md"),
            format!("100644 blob {o2}\tdocs/plans/a.md"),
            format!("100644 blob {o2}\tdocs/plans-old/a.md"),
            format!("120000 blob {o1}\tdocs/plans/link"),
            format!("100644 blob {o1}\tx/docs/plans/a.md"),
        ];
        let several_id = "0fca850e419d8a202129087fd90f00fe285c4b9cc63b42f4db6162e0a2b12eaf";
        assert_eq!(id(&several), several_id);
        // so a plan's existence does not count, unlike attest's canon(T)
        assert_eq!(
            id(&[several[0].clone(), several[2].clone(), several[4].clone()]),
            several_id
        );
        // a raw path with a newline: no quoting, no decoding
        assert_eq!(
            id(&[
                format!("100644 blob {o1}\tdocs/a\nb.md"),
                format!("100644 blob {o2}\tdocs/plans/c\nd.md"),
            ]),
            "88a9c5d4a7b3892be98a8492631b3c436954c2000a038b5d641bd054e76e19e0"
        );
    }

    fn reviews_of(text: &str) -> Vec<(String, Option<Verdict>)> {
        completed_agents_resumable(text.as_bytes(), AGENT)
            .into_iter()
            .flat_map(|c| {
                let v = verdict_of(&c.result);
                parse_blocks(&c.prompt)
                    .into_iter()
                    .map(move |(_, sha)| (sha, v))
            })
            .collect()
    }

    #[test]
    fn each_resumed_round_is_a_review_of_its_own_tree() {
        assert_eq!(
            reviews_of(RESUMED),
            vec![
                (LAUNCH_TREE.to_string(), Some(Verdict::ApproveWithChanges)),
                (ROUND_2.to_string(), Some(Verdict::Approve)),
                (ROUND_3.to_string(), Some(Verdict::Approve)),
            ],
            "the launch keeps its own verdict"
        );
    }

    #[test]
    fn the_shared_reader_counts_the_launch_alone() {
        // What the plan-review panel reads: a resume is not a launch.
        let launches = crate::plan_review::completed_agents(RESUMED.as_bytes(), AGENT);
        assert_eq!(launches.len(), 1);
        assert!(launches[0].prompt.contains(LAUNCH_TREE));
        assert_eq!(
            verdict_of(&launches[0].result),
            Some(Verdict::ApproveWithChanges),
            "the rounds' notifications do not overwrite the launch's"
        );
    }

    #[test]
    fn a_resume_of_an_agent_that_is_not_a_reviewer_does_not_count() {
        let other = RESUMED.replace(
            "\"subagent_type\":\"implementation-review\"",
            "\"subagent_type\":\"general-purpose\"",
        );
        assert!(reviews_of(&other).is_empty());
        // The message went to another agent than the one that resumed.
        let elsewhere = RESUMED.replace(
            "\"to\":\"aa339dbce3244a139\"",
            "\"to\":\"a0000000000000000\"",
        );
        assert_eq!(reviews_of(&elsewhere).len(), 1);
    }

    #[test]
    fn a_resumed_round_needs_its_own_agents_structured_notification() {
        // Another task's id on the round's notifications.
        let lines: Vec<String> = RESUMED
            .lines()
            .map(|l| {
                if l.contains("\"origin\":{\"kind\":\"task-notification\"") {
                    l.replace(
                        "<task-id>aa339dbce3244a139</task-id>",
                        "<task-id>a0000000000000000</task-id>",
                    )
                } else {
                    l.to_string()
                }
            })
            .collect();
        assert_eq!(reviews_of(&lines.join("\n")).len(), 1);

        // The round's notifications echoed in a tool result and typed by a
        // person: neither was queued by Claude Code.
        let forged: Vec<String> = RESUMED
            .lines()
            .map(|l| {
                if l.contains("\"origin\":{\"kind\":\"task-notification\"") {
                    l.replace(
                        "\"origin\":{\"kind\":\"task-notification\"",
                        "\"origin\":{\"kind\":\"human\"",
                    )
                } else {
                    l.to_string()
                }
            })
            .collect();
        assert_eq!(reviews_of(&forged.join("\n")).len(), 1);
    }

    #[test]
    fn a_block_round_trips_and_a_short_sha_does_not_bind() {
        let sha = "a".repeat(64);
        let b = block("amont-agent", &sha);
        assert_eq!(b, format!("<<<TREE repo=amont-agent sha={sha}>>>"));
        assert_eq!(
            parse_blocks(&format!("Round 1.\n{b}\nbrief")),
            vec![("amont-agent".to_string(), sha.clone())]
        );
        assert!(parse_blocks("<<<TREE repo=x sha=abc123>>>").is_empty());
        assert!(parse_blocks("<<<TREE sha=abc>>>").is_empty());
        assert!(parse_blocks(&format!("<<<TREE repo= sha={sha}>>>")).is_empty());
    }

    #[test]
    fn the_sha_is_lowercased() {
        let sha = "A".repeat(64);
        let got = parse_blocks(&block("r", &sha));
        assert_eq!(got[0].1, "a".repeat(64));
    }

    #[test]
    fn the_verdict_is_the_first_verdict_line() {
        assert_eq!(
            verdict_of("Verdict: approve\nFindings:"),
            Some(Verdict::Approve)
        );
        assert_eq!(
            verdict_of("**Verdict: approve-with-changes**\n"),
            Some(Verdict::ApproveWithChanges)
        );
        assert_eq!(
            verdict_of("preamble\nVerdict: rework"),
            Some(Verdict::Rework)
        );
        assert_eq!(verdict_of("no verdict here"), None);
        assert_eq!(verdict_of("Verdict: maybe"), None);
    }

    #[test]
    fn the_marker_splits_at_the_last_at_and_wants_64_hex() {
        let sha = "b".repeat(64);
        assert_eq!(
            marker(&format!("[implementation-review my@repo@{sha}] Overrule?")),
            Some(("my@repo".to_string(), sha.clone()))
        );
        assert_eq!(marker("[implementation-review repo@abc] x"), None);
        assert_eq!(marker(&format!("[implementation-review @{sha}]")), None);
        assert_eq!(marker("[preview a1] x"), None);
    }

    #[test]
    fn lexical_folds_dot_and_dotdot() {
        assert_eq!(lexical(Path::new("/a/b/../c/./d")), PathBuf::from("/a/c/d"));
    }

    #[test]
    fn a_read_of_the_store_passes_and_a_write_does_not() {
        use amont_agent_guard::shell::lex;
        let store = "~/.claude/amont-agent/implementation-review/by-tree/r/x.json";
        for read in [
            format!("ls {store}"),
            format!("cat {store} | head"),
            "find ~/.claude/amont-agent/implementation-review -type f".to_string(),
            format!("grep verdict {store}"),
        ] {
            assert!(store_clause(&lex(&read)).is_none(), "{read}");
        }
        for write in [
            format!("echo '{{}}' > {store}"),
            format!("printf x >> {store}"),
            format!("rm -f {store}"),
            format!("cp /tmp/x {store}"),
            format!("python3 -c 'open(\"{store}\",\"w\")'"),
            format!("tee {store} < /dev/null"),
            format!("cat x | sudo tee {store}"),
        ] {
            assert!(store_clause(&lex(&write)).is_some(), "{write}");
        }
    }

    #[test]
    fn a_word_names_the_store_by_its_directory() {
        assert!(names_store(
            "/Users/me/.claude/amont-agent/implementation-review/by-tree/r/x.json"
        ));
        assert!(names_store("~/.claude/amont-agent/implementation-review"));
        assert!(names_store(
            "C:\\Users\\me\\.claude\\amont-agent\\implementation-review\\by-tree\\r\\x.json"
        ));
        assert!(!names_store("~/.claude/amont-agent/journal.log"));
        assert!(!names_store("implementation-review"));
        // The outcome ledger lives beside the store, not in it.
        assert!(!names_store(
            "~/.claude/amont-agent/implementation-review-outcomes/outcomes.jsonl"
        ));
    }
}