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

tools/CONTRACT.md

@@ -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.