feat: INSTALL.md held to the installation instructions - prerequisites lists generated from the manifest, setup questions checked by docs verify (#154)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01SnAJ7Z3CpVD3PRbN73QtU2 Files changed: - CHANGES.md - INSTALL.md - VERSION - instructions/dev/doc-pull-through.md - instructions/dev/stack-close/SKILL.md - instructions/setup-instance.md - tools/CONTRACT.md - tools/README.md - tools/chemenu/cli_contract.py - tools/chemenu/commands/docs_verify.py - tools/chemenu/install_doc.py - tools/chemenu/tests/test_install_doc.py
2026-10-02 07:47:39 +02:00
1 parent b33088f64e
commit c77bda2004
@@ -132,6 +132,7 @@ instructions verify   read  idempotent     budget:counted              exit:0,1
 instructions list     read  idempotent     budget:counted              exit:0      List the flat instructions with their descriptions.
 docs verify           read  idempotent     budget:counted              exit:0,1    Check the docs that mirror the code.
 docs toc              write idempotent     budget:counted              exit:0      Create, refresh or remove the generated table-of-contents region.
+docs prerequisites    write idempotent     budget:counted              exit:0,1    Regenerate `INSTALL.md`'s prerequisites lists from `tools/prerequisites.txt`.
 docs contract         write idempotent     budget:counted              exit:0,1    Regenerate `tools/CONTRACT.md`'s `<!-- wikitool:commands -->` region.
 eval sessions         read  idempotent     budget:exempt               exit:0      List the sessions that have a trace under `reports/telemetry/`.
 eval score            read  idempotent     budget:exempt               exit:0,1    Score one traced session.
@@ -2182,6 +2183,9 @@ Check the docs that mirror the code.
 - 1    A shipped `.md`/`.template` cites an issue number
 - 1    A reference file's table-of-contents region is missing or stale
 - 1    A reference file's relative markdown link does not resolve to an existing file
+- 1    An `INSTALL.md` prerequisites region is stale
+- 1    An `INSTALL.md` prerequisites region is missing, or names a platform no tool has
+- 1    A setup question is marked in one of `instructions/setup-instance.md` and `INSTALL.md` but not the other

 **ON FAILURE**

@@ -2191,6 +2195,9 @@ Check the docs that mirror the code.
 - A shipped `.md`/`.template` cites an issue number -> Say what was decided instead of pointing at where, or move the pointer behind a `<!-- dist:strip-start/end -->` block
 - A reference file's table-of-contents region is missing or stale -> Run `docs toc --apply`, then re-run
 - A reference file's relative markdown link does not resolve to an existing file -> Fix the `../` count or the target's name
+- An `INSTALL.md` prerequisites region is stale -> Run `docs prerequisites --apply`, then re-run
+- An `INSTALL.md` prerequisites region is missing, or names a platform no tool has -> Add the marker pair where that list belongs (or remove the orphaned region and its introducing prose), then run `docs prerequisites --apply`
+- A setup question is marked in one of `instructions/setup-instance.md` and `INSTALL.md` but not the other -> Describe the question for the human in `INSTALL.md` with the same marker, or remove the bullet for a question no longer asked

 **NEVER**

@@ -2207,12 +2214,14 @@ Check the docs that mirror the code.
 - No `.md`/`.template` file `dist export` would ship cites an issue number. A `<!-- dist:strip-start/end -->` region is exempt: the check reads the export plan's text, from which it is already gone.
 - Every reference file `docs toc` covers carries the current table-of-contents region for its own headings - missing and stale are one check.
 - Every relative markdown link in one of those reference files resolves to an existing file. A target's `#anchor` suffix is stripped first, and code fences and inline code spans are masked before scanning, so link syntax shown as an example is not mistaken for a real reference.
+- `INSTALL.md` carries one generated `<!-- wikitool:prerequisites -->` region per platform value of `tools/prerequisites.txt` (`prerequisites-<platform>` for a platform-specific one), each current; and the `<!-- setup-question: <key> -->` markers in `instructions/setup-instance.md` and `INSTALL.md` name the same set of keys, so a question the agent asks is never one the human guide leaves out, nor the reverse.
 - Read-only.

 **SEE ALSO**

 - `wikitool docs toc` - regenerates tables of contents
 - `wikitool docs contract` - regenerates the commands region
+- `wikitool docs prerequisites` - regenerates `INSTALL.md`'s prerequisites lists
 - `wikitool instructions verify` - the same kind of check for `instructions/`

 #### `docs toc`
@@ -2257,6 +2266,51 @@ Create, refresh or remove the generated table-of-contents region.

 - `wikitool docs verify` - checks every region is current

+#### `docs prerequisites`
+
+Regenerate `INSTALL.md`'s prerequisites lists from `tools/prerequisites.txt`.
+
+**SYNOPSIS**
+
+- `wikitool docs prerequisites [--apply]`
+
+**PROPERTIES**
+
+- effect: write
+- idempotent: yes
+- atomic: Yes - every region is rewritten in one file write
+- budget: counted
+- network: no
+
+**EXAMPLES**
+
+- `tools/wikitool docs prerequisites`
+- `tools/wikitool docs prerequisites --apply`
+
+**EXIT STATUS**
+
+- 0    success
+- 1    `INSTALL.md` is missing, or lacks a region the manifest calls for
+
+**ON FAILURE**
+
+- `INSTALL.md` is missing, or lacks a region the manifest calls for -> Not transient - add the marker pair the message names where that list belongs (restore the file if it is gone), then retry
+
+**NEVER**
+
+- Never hand-edit a prerequisites region - change `tools/prerequisites.txt` and re-run this.
+
+**NOTES**
+
+- Rewrites each `<!-- wikitool:prerequisites -->` region in `INSTALL.md` (tools every platform needs) and `<!-- wikitool:prerequisites-<platform> -->` region (tools only that platform needs) from the manifest: one list item per tool, its label and minimum version. The manifest's reason field stays out - it is English prose, and the region sits in a document that need not be.
+- Never places a region: where a list belongs in the human guide is that guide's own decision. A region the manifest calls for but the file lacks is an error naming the marker pair to add.
+- Dry-run by default (says whether the file would change); `--apply` writes.
+- `docs verify` checks the result stays current.
+
+**SEE ALSO**
+
+- `wikitool docs verify` - checks every region is current
+
 #### `docs contract`

 Regenerate `tools/CONTRACT.md`'s `<!-- wikitool:commands -->` region.
@@ -85,6 +85,7 @@ tools/
    toolpaths.py           where git and rg are started from: .wikitool-tools.json, bare name only without the file
    filelock.py            an exclusive lock on an open file, flock on POSIX and msvcrt on Windows - the only module that imports either
    prerequisites.py       prerequisites.txt read from Python, plus the platform and long-path questions `doctor` asks
+    install_doc.py         INSTALL.md held to the instructions: its prerequisites lists generated from prerequisites.txt, its setup questions matched to setup-instance.md's markers
    corpus_cache.py        one parsed corpus per commit, never cached while the tree is dirty
    kb_scan.py             page iteration/loading over kb/
    blocks.py              generated regions in a page body, found by marker rather than by heading
@@ -270,7 +270,7 @@ GROUPS: tuple[tuple[str, tuple[str, ...]], ...] = (
    ("Types, instructions and docs", (
        "types list", "types describe",
        "instructions sync", "instructions verify", "instructions list",
-        "docs verify", "docs toc", "docs contract",
+        "docs verify", "docs toc", "docs prerequisites", "docs contract",
    )),
    ("Telemetry", (
        "eval sessions", "eval score",
@@ -68,7 +68,7 @@ from typing import Optional

 import typer

-from chemenu import blocks, cli_contract, config, conventions, kb_collections, markdown_code, toc, toolpaths, version as version_mod
+from chemenu import blocks, cli_contract, config, conventions, install_doc, kb_collections, markdown_code, toc, toolpaths, version as version_mod
 from chemenu.commands import dist_cmd
 from chemenu.commands._util import fail, rel_path, success

@@ -1078,6 +1078,11 @@ def check_breaking_change_for_boundary() -> list[str]:
        "file. A target's `#anchor` suffix is stripped first, and code fences and inline code "
        "spans are masked before scanning, so link syntax shown as an example is not mistaken "
        "for a real reference.",
+        "`INSTALL.md` carries one generated `<!-- wikitool:prerequisites -->` region per "
+        "platform value of `tools/prerequisites.txt` (`prerequisites-<platform>` for a "
+        "platform-specific one), each current; and the `<!-- setup-question: <key> -->` markers "
+        "in `instructions/setup-instance.md` and `INSTALL.md` name the same set of keys, so a "
+        "question the agent asks is never one the human guide leaves out, nor the reverse.",
        "Read-only.",
    ),
    failures=(
@@ -1108,6 +1113,22 @@ def check_breaking_change_for_boundary() -> list[str]:
            "file",
            reaction="Fix the `../` count or the target's name",
        ),
+        cli_contract.Failure(
+            cause="An `INSTALL.md` prerequisites region is stale",
+            reaction="Run `docs prerequisites --apply`, then re-run",
+        ),
+        cli_contract.Failure(
+            cause="An `INSTALL.md` prerequisites region is missing, or names a platform no tool "
+            "has",
+            reaction="Add the marker pair where that list belongs (or remove the orphaned region "
+            "and its introducing prose), then run `docs prerequisites --apply`",
+        ),
+        cli_contract.Failure(
+            cause="A setup question is marked in one of `instructions/setup-instance.md` and "
+            "`INSTALL.md` but not the other",
+            reaction="Describe the question for the human in `INSTALL.md` with the same marker, "
+            "or remove the bullet for a question no longer asked",
+        ),
    ),
    examples=(
        "tools/wikitool docs verify",
@@ -1118,6 +1139,7 @@ def check_breaking_change_for_boundary() -> list[str]:
    see_also=(
        "`wikitool docs toc` - regenerates tables of contents",
        "`wikitool docs contract` - regenerates the commands region",
+        "`wikitool docs prerequisites` - regenerates `INSTALL.md`'s prerequisites lists",
        "`wikitool instructions verify` - the same kind of check for `instructions/`",
    ),
 ))
@@ -1139,6 +1161,8 @@ def verify():
        + check_no_issue_references()
        + check_toc_regions()
        + check_reference_targets()
+        + install_doc.check_prerequisite_regions()
+        + install_doc.check_setup_questions()
    )

    if issues:
@@ -1155,6 +1179,8 @@ def verify():
        f"no issue references in {len(shipped_prose())} shipped document(s) or command help, "
        f"tables of contents current and every link resolving on "
        f"{len(toc.target_files())} reference file(s), "
+        f"{install_doc.INSTALL_DOC} in step with tools/prerequisites.txt and "
+        f"{install_doc.SETUP_INSTRUCTION}'s questions, "
        f"{version_mod.CHANGES_FILENAME} documents version "
        f"{(config.ROOT / version_mod.VERSION_FILENAME).read_text(encoding='utf-8').strip()}."
    )
@@ -1235,6 +1261,79 @@ def toc_command(
        typer.echo(f"\n{len(changed)} file(s) would change. Re-run with --apply to write.")


+@app.command("prerequisites")
+@cli_contract.record(cli_contract.CommandRecord(
+    path="docs prerequisites",
+    summary="Regenerate `INSTALL.md`'s prerequisites lists from `tools/prerequisites.txt`.",
+    synopsis=(cli_contract.Variant(usage="docs prerequisites [--apply]"),),
+    properties=cli_contract.Properties(
+        effect=cli_contract.Effect.WRITE,
+        idempotent=cli_contract.Idempotent.YES,
+        atomic="Yes - every region is rewritten in one file write",
+        budget=cli_contract.Budget.COUNTED,
+    ),
+    notes=(
+        "Rewrites each `<!-- wikitool:prerequisites -->` region in `INSTALL.md` (tools every "
+        "platform needs) and `<!-- wikitool:prerequisites-<platform> -->` region (tools only that "
+        "platform needs) from the manifest: one list item per tool, its label and minimum "
+        "version. The manifest's reason field stays out - it is English prose, and the region "
+        "sits in a document that need not be.",
+        "Never places a region: where a list belongs in the human guide is that guide's own "
+        "decision. A region the manifest calls for but the file lacks is an error naming the "
+        "marker pair to add.",
+        "Dry-run by default (says whether the file would change); `--apply` writes.",
+        "`docs verify` checks the result stays current.",
+    ),
+    failures=(cli_contract.Failure(
+        cause="`INSTALL.md` is missing, or lacks a region the manifest calls for",
+        reaction="Not transient - add the marker pair the message names where that list "
+        "belongs (restore the file if it is gone), then retry",
+    ),),
+    examples=(
+        "tools/wikitool docs prerequisites",
+        "tools/wikitool docs prerequisites --apply",
+    ),
+    never=(
+        "Never hand-edit a prerequisites region - change `tools/prerequisites.txt` and re-run "
+        "this.",
+    ),
+    see_also=(
+        "`wikitool docs verify` - checks every region is current",
+    ),
+))
+def prerequisites_command(
+    apply: bool = typer.Option(False, "--apply", help="Write changes; default is dry-run (preview only)"),
+):
+    """Regenerate `INSTALL.md`'s prerequisites lists from `tools/prerequisites.txt`."""
+    from chemenu import prerequisites
+
+    path = install_doc.install_doc_path()
+    if not path.is_file():
+        fail(f"{install_doc.INSTALL_DOC} is missing.")
+
+    text = path.read_text(encoding="utf-8")
+    after, missing = install_doc.refresh(text, prerequisites.load_manifest())
+    if missing:
+        fail(
+            f"{install_doc.INSTALL_DOC} lacks "
+            + ", ".join(f"`{blocks.open_marker(name)}`" for name in missing)
+            + " - add each marker pair (with its closing marker) where that list belongs, "
+            "then re-run."
+        )
+
+    if after == text:
+        success(f"{install_doc.INSTALL_DOC}'s prerequisites lists are already current.")
+        return
+
+    if not apply:
+        typer.echo(f"{install_doc.INSTALL_DOC} would change.")
+        typer.echo("Re-run with --apply to write.")
+        return
+
+    path.write_text(after, encoding="utf-8", newline="\n")
+    success(f"Regenerated the prerequisites lists in {install_doc.INSTALL_DOC}.")
+
+
@app.command("contract")
@cli_contract.record(cli_contract.CommandRecord(
    path="docs contract",
@@ -0,0 +1,178 @@
+"""The two places `INSTALL.md` overlaps the installation instructions, held to them.
+
+`INSTALL.md` is written for a human and in the instance's KB language;
+`instructions/setup-instance.md` is written for an agent and in English. A
+single file serving both was rejected: an agent reads every sentence as an
+instruction, and the human needs preparation and decisions where the agent
+needs steps and exit codes. So the human document does not retell the
+procedure, and what it still shares with the instructions is two enumerable
+lists - both checked here, so neither can drift silently:
+
+1. **What the machine needs.** `tools/prerequisites.txt` is the one list; the
+   preflight and `doctor` read it. `INSTALL.md` carries it as a generated
+   region per platform value (`<!-- wikitool:prerequisites -->` for `all`,
+   `<!-- wikitool:prerequisites-<platform> -->` otherwise), rendered from the
+   label and minimum version only. The manifest's `why` field stays out: it is
+   English prose, and the region sits in a document that is not. A region is
+   never placed by the tool - where it goes is the human document's own
+   decision - so a missing one is reported, not appended.
+2. **What the agent asks the user.** Every place `setup-instance.md` puts a
+   question to the user carries `<!-- setup-question: <key> -->`, and the
+   bullet in `INSTALL.md` that tells the human about it carries the same
+   marker. The two key sets must be equal: a question the human guide does not
+   mention catches them unprepared, and one it mentions that is no longer asked
+   is a claim about a procedure that no longer exists. The key is the shared
+   identifier precisely because the surrounding prose is in two languages.
+
+Everything else in `INSTALL.md` is prose no check reads;
+`instructions/dev/doc-pull-through.md` names it as session work.
+"""
+from __future__ import annotations
+
+import re
+from pathlib import Path
+
+from chemenu import blocks, config, prerequisites
+
+INSTALL_DOC = "INSTALL.md"
+SETUP_INSTRUCTION = "instructions/setup-instance.md"
+
+REGION_PREFIX = "prerequisites"
+
+QUESTION_RE = re.compile(r"<!-- setup-question: ([a-z][a-z0-9-]*) -->")
+
+
+def install_doc_path() -> Path:
+    return config.ROOT / INSTALL_DOC
+
+
+def setup_instruction_path() -> Path:
+    return config.ROOT / SETUP_INSTRUCTION
+
+
+def region_name(platform: str) -> str:
+    """`prerequisites` for the tools every platform needs, `prerequisites-<platform>`
+    for the ones only that platform does."""
+    return REGION_PREFIX if platform == "all" else f"{REGION_PREFIX}-{platform}"
+
+
+def render_lines(tools: tuple[prerequisites.Tool, ...]) -> list[str]:
+    """One list item per tool - label and minimum version, nothing in a language."""
+    return [
+        f"- **{tool.label}**" + (f" ≥ {tool.minimum}" if tool.minimum else "")
+        for tool in tools
+    ]
+
+
+def expected_regions(manifest: prerequisites.Manifest) -> dict[str, str]:
+    """Region name -> the whole region, markers included, in manifest order of
+    first appearance of each platform value."""
+    platforms: list[str] = []
+    for tool in manifest.tools:
+        if tool.platforms not in platforms:
+            platforms.append(tool.platforms)
+    regions = {}
+    for platform in platforms:
+        name = region_name(platform)
+        tools = tuple(t for t in manifest.tools if t.platforms == platform)
+        regions[name] = "\n".join(
+            [blocks.open_marker(name), *render_lines(tools), blocks.close_marker(name)]
+        )
+    return regions
+
+
+def _region_span(text: str, name: str) -> tuple[int, int] | None:
+    """Start and end offset of `name`'s region, markers included - without the
+    blank lines `blocks` takes along, so a refresh leaves the prose around it
+    exactly as it was."""
+    start = text.find(blocks.open_marker(name))
+    if start < 0:
+        return None
+    close = blocks.close_marker(name)
+    end = text.find(close, start)
+    if end < 0:
+        return None
+    return start, end + len(close)
+
+
+def refresh(text: str, manifest: prerequisites.Manifest) -> tuple[str, list[str]]:
+    """`text` with every prerequisites region it carries rewritten from the
+    manifest, plus the names of the regions it lacks.
+
+    A region the manifest no longer has a platform for is left alone and
+    reported by `check_prerequisite_regions`, not deleted here: the prose
+    introducing it ("Unter Windows zusätzlich:") would otherwise be left
+    standing over nothing.
+    """
+    missing = []
+    for name, region in expected_regions(manifest).items():
+        span = _region_span(text, name)
+        if span is None:
+            missing.append(name)
+            continue
+        text = text[: span[0]] + region + text[span[1]:]
+    return text, missing
+
+
+def _present_region_names(text: str) -> set[str]:
+    pattern = re.compile(
+        rf"<!-- wikitool:({re.escape(REGION_PREFIX)}(?:-[a-z0-9-]+)?) -->"
+    )
+    return set(pattern.findall(text))
+
+
+def check_prerequisite_regions() -> list[str]:
+    """`INSTALL.md` carries one current region per platform value of the manifest."""
+    path = install_doc_path()
+    if not path.is_file():
+        return [f"{INSTALL_DOC} is missing - the human installation guide is a stack file"]
+    text = path.read_text(encoding="utf-8")
+    manifest = prerequisites.load_manifest()
+    refreshed, missing = refresh(text, manifest)
+
+    issues = [
+        f"{INSTALL_DOC} has no `{blocks.open_marker(name)}` region - add the marker pair "
+        f"where that list belongs, then run `wikitool docs prerequisites --apply`"
+        for name in missing
+    ]
+    issues += [
+        f"{INSTALL_DOC} carries `{blocks.open_marker(name)}`, but no tool in "
+        "tools/prerequisites.txt has that platform - remove the region and the prose "
+        "introducing it"
+        for name in sorted(_present_region_names(text) - set(expected_regions(manifest)))
+    ]
+    if refreshed != text:
+        issues.append(
+            f"{INSTALL_DOC}'s prerequisites list no longer matches tools/prerequisites.txt - "
+            "run `wikitool docs prerequisites --apply`"
+        )
+    return issues
+
+
+def question_keys(text: str) -> set[str]:
+    return set(QUESTION_RE.findall(text))
+
+
+def check_setup_questions() -> list[str]:
+    """Every question `setup-instance.md` asks is named in `INSTALL.md`, and
+    `INSTALL.md` names no question that is no longer asked."""
+    setup = setup_instruction_path()
+    install = install_doc_path()
+    if not setup.is_file() or not install.is_file():
+        # A missing INSTALL.md is check_prerequisite_regions' finding; a
+        # missing setup instruction leaves nothing to compare against.
+        return []
+    asked = question_keys(setup.read_text(encoding="utf-8"))
+    named = question_keys(install.read_text(encoding="utf-8"))
+
+    issues = [
+        f"{SETUP_INSTRUCTION} asks the user `{key}`, but {INSTALL_DOC} § \"Was der Agent dich "
+        f"fragt\" does not name it - add a bullet carrying `<!-- setup-question: {key} -->`"
+        for key in sorted(asked - named)
+    ]
+    issues += [
+        f"{INSTALL_DOC} names the setup question `{key}`, which {SETUP_INSTRUCTION} no longer "
+        "asks - remove the bullet, or restore the marker where the question is asked"
+        for key in sorted(named - asked)
+    ]
+    return issues
@@ -0,0 +1,173 @@
+from typer.testing import CliRunner
+
+from chemenu import config, install_doc, prerequisites
+from chemenu.cli import app
+
+runner = CliRunner()
+
+MANIFEST = prerequisites.Manifest(
+    limits={},
+    tools=(
+        prerequisites.Tool("python", "3.11", "all", "Python", "why"),
+        prerequisites.Tool("git", None, "all", "Git", "why"),
+        prerequisites.Tool("pwsh", "7", "windows", "PowerShell 7 (pwsh)", "why"),
+    ),
+)
+
+CURRENT = """# Installation
+
+Vorher:
+
+<!-- wikitool:prerequisites -->
+- **Python** ≥ 3.11
+- **Git**
+<!-- /wikitool:prerequisites -->
+
+Unter Windows zusätzlich:
+
+<!-- wikitool:prerequisites-windows -->
+- **PowerShell 7 (pwsh)** ≥ 7
+<!-- /wikitool:prerequisites-windows -->
+
+## Was der Agent dich fragt
+
+- <!-- setup-question: identity --> **Autor-Identität** - Name und E-Mail.
+"""
+
+SETUP = """# Set up
+
+2. <!-- setup-question: identity --> **Decision point - identity.** Ask the user.
+"""
+
+
+def _tree(tmp_path, monkeypatch, install=CURRENT, setup=SETUP, manifest=MANIFEST):
+    monkeypatch.setattr(config, "ROOT", tmp_path)
+    monkeypatch.setattr(prerequisites, "load_manifest", lambda path=None: manifest)
+    (tmp_path / "instructions").mkdir()
+    (tmp_path / "INSTALL.md").write_text(install, encoding="utf-8")
+    (tmp_path / "instructions" / "setup-instance.md").write_text(setup, encoding="utf-8")
+    return tmp_path
+
+
+def test_this_repos_install_doc_matches_the_manifest():
+    assert install_doc.check_prerequisite_regions() == []
+
+
+def test_this_repos_install_doc_names_every_setup_question():
+    assert install_doc.check_setup_questions() == []
+
+
+def test_this_repos_setup_instruction_marks_its_questions():
+    """The check compares two sets; an instruction that lost every marker would
+    compare empty against empty and pass. Guard the real file's own count."""
+    text = install_doc.setup_instruction_path().read_text(encoding="utf-8")
+    assert install_doc.question_keys(text) >= {
+        "identity", "remote", "kb-language", "domain",
+        "personalization", "environment", "telemetry", "task-tracker",
+    }
+
+
+def test_render_lines_are_label_and_minimum_only():
+    assert install_doc.render_lines(MANIFEST.tools) == [
+        "- **Python** ≥ 3.11",
+        "- **Git**",
+        "- **PowerShell 7 (pwsh)** ≥ 7",
+    ]
+
+
+def test_a_current_install_doc_passes(tmp_path, monkeypatch):
+    _tree(tmp_path, monkeypatch)
+    assert install_doc.check_prerequisite_regions() == []
+    assert install_doc.check_setup_questions() == []
+
+
+def test_a_manifest_tool_missing_from_install_doc_fails(tmp_path, monkeypatch):
+    """Acceptance criterion: a tool in the manifest that INSTALL.md lacks fails `docs verify`."""
+    _tree(tmp_path, monkeypatch, install=CURRENT.replace("- **Git**\n", ""))
+    issues = install_doc.check_prerequisite_regions()
+    assert any("no longer matches tools/prerequisites.txt" in issue for issue in issues)
+
+
+def test_a_new_platform_without_a_region_fails(tmp_path, monkeypatch):
+    manifest = prerequisites.Manifest(
+        limits={},
+        tools=MANIFEST.tools + (prerequisites.Tool("brew", None, "macos", "Homebrew", "why"),),
+    )
+    _tree(tmp_path, monkeypatch, manifest=manifest)
+    issues = install_doc.check_prerequisite_regions()
+    assert any("<!-- wikitool:prerequisites-macos -->" in issue for issue in issues)
+
+
+def test_a_region_for_a_platform_no_tool_has_fails(tmp_path, monkeypatch):
+    manifest = prerequisites.Manifest(limits={}, tools=MANIFEST.tools[:2])
+    _tree(tmp_path, monkeypatch, manifest=manifest)
+    issues = install_doc.check_prerequisite_regions()
+    assert any("prerequisites-windows" in issue and "no tool" in issue for issue in issues)
+
+
+def test_a_missing_install_doc_is_reported(tmp_path, monkeypatch):
+    _tree(tmp_path, monkeypatch)
+    (tmp_path / "INSTALL.md").unlink()
+    assert any("missing" in issue for issue in install_doc.check_prerequisite_regions())
+    assert install_doc.check_setup_questions() == []
+
+
+def test_refresh_touches_nothing_outside_the_regions(tmp_path):
+    stale = CURRENT.replace("≥ 3.11", "≥ 3.9")
+    refreshed, missing = install_doc.refresh(stale, MANIFEST)
+    assert missing == []
+    assert refreshed == CURRENT
+
+
+def test_refresh_is_idempotent():
+    once, _ = install_doc.refresh(CURRENT, MANIFEST)
+    twice, _ = install_doc.refresh(once, MANIFEST)
+    assert once == twice == CURRENT
+
+
+def test_a_question_the_install_doc_does_not_name_fails(tmp_path, monkeypatch):
+    """Acceptance criterion: a new question in setup-instance.md that INSTALL.md
+    does not name fails `docs verify`."""
+    setup = SETUP + "\n3. <!-- setup-question: remote --> **Decision point - remote.**\n"
+    _tree(tmp_path, monkeypatch, setup=setup)
+    issues = install_doc.check_setup_questions()
+    assert len(issues) == 1
+    assert "`remote`" in issues[0] and "does not name it" in issues[0]
+
+
+def test_a_question_no_longer_asked_fails(tmp_path, monkeypatch):
+    install = CURRENT + "- <!-- setup-question: telemetry --> **Telemetrie**\n"
+    _tree(tmp_path, monkeypatch, install=install)
+    issues = install_doc.check_setup_questions()
+    assert len(issues) == 1
+    assert "`telemetry`" in issues[0] and "no longer asks" in issues[0]
+
+
+def test_docs_prerequisites_is_a_dry_run_by_default(tmp_path, monkeypatch):
+    stale = CURRENT.replace("≥ 3.11", "≥ 3.9")
+    root = _tree(tmp_path, monkeypatch, install=stale)
+    result = runner.invoke(app, ["docs", "prerequisites"])
+    assert result.exit_code == 0, result.output
+    assert "would change" in result.output
+    assert (root / "INSTALL.md").read_text(encoding="utf-8") == stale
+
+
+def test_docs_prerequisites_apply_rewrites_the_regions(tmp_path, monkeypatch):
+    root = _tree(tmp_path, monkeypatch, install=CURRENT.replace("≥ 3.11", "≥ 3.9"))
+    result = runner.invoke(app, ["docs", "prerequisites", "--apply"])
+    assert result.exit_code == 0, result.output
+    assert (root / "INSTALL.md").read_text(encoding="utf-8") == CURRENT
+    assert install_doc.check_prerequisite_regions() == []
+
+
+def test_docs_prerequisites_never_places_a_missing_region(tmp_path, monkeypatch):
+    without_windows = CURRENT.replace(
+        "<!-- wikitool:prerequisites-windows -->\n- **PowerShell 7 (pwsh)** ≥ 7\n"
+        "<!-- /wikitool:prerequisites-windows -->\n",
+        "",
+    )
+    root = _tree(tmp_path, monkeypatch, install=without_windows)
+    result = runner.invoke(app, ["docs", "prerequisites", "--apply"])
+    assert result.exit_code == 1
+    assert "prerequisites-windows" in result.output
+    assert (root / "INSTALL.md").read_text(encoding="utf-8") == without_windows