brain-of-reese/tests/unit/test_read_truncation_frontend.py

"""Unit: the phase-95 (task 02) truncation-marker frontend contract.

No new Python app logic exists for the marker itself — the behavior
lives in ``frontend/assets/app.js`` (the ``tool_result`` SSE branch +
the ``toolAcc`` stamp + the phase-14 restore marker),
``frontend/assets/shared.js`` (the shared page's local tool-line
render) and ``frontend/assets/styles.css`` (the theme-neutral
``.truncated-note`` rule). Like the other frontend-adjacent unit files
(``test_frontend_tool_states.py`` is the phase-37 precedent), this
module pins the JS/CSS markers the story depends on, so a silent
regression in the handler, the pinned marker copy, the persistence
stamp, or the styling is caught without a browser. The E2E gate is the
phase's story suite (task 03).
"""
from __future__ import annotations

import re
from pathlib import Path

FRONTEND = Path(__file__).resolve().parents[2] / "frontend"
APP_JS = FRONTEND / "assets" / "app.js"
SHARED_JS = FRONTEND / "assets" / "shared.js"
STYLES_CSS = FRONTEND / "assets" / "styles.css"

#: The pinned marker copy (the unit + E2E assertion target): plain
#: integers, no thousands separators, the em-dash per the owner's TODO.
MARKER_TEMPLATE = '" (truncated — showing "'


def _js() -> str:
    return APP_JS.read_text(encoding="utf-8")


def _shared_js() -> str:
    return SHARED_JS.read_text(encoding="utf-8")


def _css() -> str:
    return STYLES_CSS.read_text(encoding="utf-8")


def test_tool_result_branch_is_a_first_class_turn_branch() -> None:
    """The turn handler must branch on `tool_result` frames (the
    seventh, optional event type — the A15 extension): the branch sits
    after `done` (a frame for a settled turn is a tolerated late
    append, never a crash) and before `error`, settles the tool-line
    clock like every other frame, and must never flip the state
    machine (the phase-37/48 lifecycle is untouched)."""
    js = _js()
    done_idx = js.find('ev.type === "done"')
    tool_result_idx = js.find('ev.type === "tool_result"')
    error_idx = js.find('ev.type === "error"')
    assert -1 < done_idx < tool_result_idx < error_idx, (
        "the turn handler must branch on tool_result frames (after done,"
        " before error)"
    )
    branch = js[tool_result_idx:error_idx]
    assert "settleToolLine()" in branch, (
        "a frame arrived — the latest tool line's elapsed clock settles"
    )
    assert "appendTruncatedNote(wrap, argument, shown, total)" in branch
    # No UI-state transition: the state machine never knows the marker.
    assert "setUiState" not in branch
    assert "aborted" not in branch, (
        "the aborted guard lives at the dispatch top, not per branch"
    )


def test_truncation_marker_copy_is_pinned() -> None:
    """The marker text is pinned EXACTLY: \" (truncated — showing N of
    M chars)\" — plain integers (no separators), a leading space (it
    follows the line's <code> child), the em-dash per the TODO copy.
    Both app.js's helper and shared.js's local render carry the same
    template (pixel-identical marker — the phase-50 restore
    contract)."""
    js = _js()
    fn = js.find("function appendTruncatedNote")
    assert fn != -1, "appendTruncatedNote must exist in app.js"
    body = js[fn : js.find("\n}\n", fn)]
    assert MARKER_TEMPLATE in body
    assert '+ charsShown + " of " + charsTotal + " chars)"' in body
    shared = _shared_js()
    fn = shared.find("function addToolLines")
    assert fn != -1
    sbody = shared[fn : shared.find("\n}\n", fn)]
    assert MARKER_TEMPLATE in sbody
    assert 'chars_shown) || 0) + " of " + (Number(t.chars_total) || 0) + " chars)"' in sbody


def test_append_truncated_note_matches_newest_line_and_uses_text_content() -> None:
    """appendTruncatedNote: the target is the NEWEST `.tool-call` line
    whose `<code>` child carries the frame's argument (the raw
    source/path — the same string the matching `tool` frame put in the
    line), scanned newest-first; the marker is a SPAN sibling appended
    to the existing line (createElement + className + textContent only
    — the house "this file never builds HTML" rule, no innerHTML); a
    frame whose line is gone (New Chat mid-turn) is a silent no-op."""
    js = _js()
    fn = js.find("function appendTruncatedNote")
    assert fn != -1
    body = js[fn : js.find("\n}\n", fn)]
    assert 'wrap?.querySelector?.(".tool-calls")' in body, (
        "a wrap without tool lines is a silent no-op"
    )
    assert 'querySelectorAll(".tool-call")' in body
    assert "for (let i = lines.length - 1; i >= 0; i -= 1)" in body, (
        "newest line first — the last call for that argument"
    )
    assert 'code.textContent !== argument' in body, (
        "the match key is the code child's argument (the raw source/path)"
    )
    assert 'note.className = "truncated-note"' in body
    assert 'lines[i].appendChild(note)' in body, (
        "DOM append to the EXISTING line — no new line, no re-render"
    )
    assert "innerHTML" not in body, (
        "no HTML injection surface — createElement + textContent only"
    )
    # The no-op guard: a wrap without tool lines returns silently; a scan
    # that finds no matching line falls off the loop without appending.
    assert "if (!calls) return;" in body


def test_tool_result_branch_stamps_the_newest_toolacc_entry() -> None:
    """The `tool_result` frame stamps the matching toolAcc entry (same
    argument, NEWEST — the reverse scan mirrors the line match) with
    `truncated` + `chars_shown` + `chars_total` — the `done` save point
    below then carries it with zero other change (the persistence
    shape rides the existing `tools` key). The stamp is gated on the
    frame's argument + truncated truth (a malformed frame is a silent
    no-op for persistence)."""
    js = _js()
    tool_result_idx = js.find('ev.type === "tool_result"')
    error_idx = js.find('ev.type === "error"')
    assert -1 < tool_result_idx < error_idx
    branch = js[tool_result_idx:error_idx]
    assert "t.truncated = true" in branch
    assert "t.chars_shown = shown" in branch
    assert "t.chars_total = total" in branch
    assert "for (let i = toolAcc.length - 1; i >= 0; i -= 1)" in branch, (
        "the NEWEST matching entry (the reverse scan, same rule as the"
        " line match) gets stamped — then break"
    )
    assert "t.argument === argument" in branch
    assert "break" in branch
    # The guard: the stamp only runs for a real truncation with an argument.
    assert "if (argument && ev.truncated)" in branch
    # The saved payload rides the existing save point — no second tools
    # key, no new record field.
    done_block = js[js.find('ev.type === "done"') : tool_result_idx]
    assert "tools: toolAcc.length ? toolAcc : undefined" in done_block


def test_restore_path_renders_the_stored_marker() -> None:
    """The phase-14 LOCAL restore path (renderStoredMessage): a stored
    tool record with `truncated` + the counts re-renders the SAME
    marker next to its Reading line, right after the line is restored
    (the same order as the live frames). A pre-phase-95 record (no
    field — `t.truncated` falsy) renders unchanged (no marker, no
    migration)."""
    js = _js()
    fn = js.find("function renderStoredMessage")
    assert fn != -1
    end = js.find("function restoreConversation")
    body = js[fn:end]
    assert "appendToolLine(wrap, t.name, arg, tOffset, tLimit)" in body
    assert "t.truncated && arg" in body, (
        "only an argument-bearing (Reading) record with the flag renders"
        " the marker"
    )
    assert (
        "appendTruncatedNote(wrap, arg, Number(t.chars_shown) || 0,"
        " Number(t.chars_total) || 0)" in body
    )
    # The marker append sits INSIDE the tools loop, after the line append.
    line_idx = body.find("appendToolLine(wrap, t.name, arg, tOffset, tLimit)")
    note_idx = body.find("appendTruncatedNote(wrap, arg,")
    assert -1 < line_idx < note_idx


def test_shared_page_renders_the_stored_marker() -> None:
    """shared.js's local tool-line render (addToolLines): the same
    marker from the stored record — a span sibling appended to the
    line, after the line's existing children (the template text + the
    <code> argument), textContent only (no HTML from storage, ever). A
    record saved before phase 95 renders exactly as before."""
    js = _shared_js()
    fn = js.find("function addToolLines")
    assert fn != -1
    body = js[fn : js.find("\n}\n", fn)]
    assert "t.truncated && argument" in body
    assert 'note.className = "truncated-note"' in body
    assert 'line.appendChild(note)' in body
    assert MARKER_TEMPLATE in body
    # Still textContent-only: the marker adds no innerHTML surface, and
    # the three argument-bearing lines keep their textContent treatment.
    assert body.count("code.textContent = argument") == 3
    assert "innerHTML" not in body


def test_truncated_note_style_is_theme_neutral() -> None:
    """styles.css: `.tool-call .truncated-note` exists and colors ONLY
    through a `var(--…)` token (the phase-92 zero-literal invariant —
    no new hue; under phase 93's monochrome theme it grays
    automatically, and the marker stays TEXT, never color alone, B5).
    --ink-soft is the AA-safe soft-ink the status suffixes already
    borrow."""
    css = _css()
    m = re.search(r"\.tool-call \.truncated-note \{([^}]*)\}", css)
    assert m, "the .tool-call .truncated-note rule must exist"
    rule = m.group(1)
    assert "var(--ink-soft)" in rule
    assert "color: var(--ink-soft)" in rule
    # Theme-neutral: the whole rule is a single var() color — no hex,
    # no rgb(), no other property.
    assert not re.search(r"#[0-9a-fA-F]{3,8}\b|rgb\(", rule)


def test_no_cdn_added() -> None:
    """AGENTS.md rule 6: the marker adds no external script/link."""
    index = (FRONTEND / "index.html").read_text(encoding="utf-8")
    assert 'src="http' not in index and 'href="http' not in index