Points readers of computations/r.qmd at QUARTO_EXECUTE_INFO so
they can branch on output format. Mirrors the additions for
Python and Julia.

Part of #13514.

The {r} marker was unescaped inside a markdown verbatim block;
Quarto would have treated it as an executable cell on render.
Matches the {{r}} escape pattern used by the sibling Chunk Labels
example in the same file.

Part of #13514.

Points readers of computations/python.qmd at QUARTO_EXECUTE_INFO
so they can branch on output format. Mirrors the additions for
R and Julia.

Part of #13514.

Points readers of computations/julia.qmd at QUARTO_EXECUTE_INFO
so they can branch on output format. Mirrors the additions for
R and Python.

Part of #13514.

Markup-based .content-visible / .content-hidden hide output but
do not skip execution. Adds a pointer section to
QUARTO_EXECUTE_INFO for the execution-level case.

Part of #13514.

Pre-existing EOF lacked a terminal newline; appending Conditional
Execution section preserved that. Aligns with other .qmd files in
the repo.

Part of #13514.

The conditional-content example in cross-references-divs.qmd
hides one branch but still runs both. Adds two pointers:
(1) QUARTO_EXECUTE_INFO for users who need to skip execution,
(2) project profiles as another axis for content variation
beyond output format. Both flagged in issue thread.

Part of #13514.

conditional.qmd and cross-references-divs.qmd both clarify that
.content-visible / .content-hidden hide output but do not skip
execution. The two paragraphs duplicated the same takeaway in
slightly different words. Extract the single canonical version
to docs/authoring/_visibility-vs-execution.md and include it
from both pages. The project-profiles paragraph in
cross-references-divs.qmd stays inline (specific to that page).

Part of #13514.

R cells run through knitr by default, which has long offered
is_html_output(), is_latex_output(), and pandoc_to() for the
common format-detection cases. Worth pointing readers at those
alongside the engine-agnostic QUARTO_EXECUTE_INFO approach
(flagged in the issue thread by cderv).

Part of #13514.

Co-authored-by: Charlotte Wickham <charlotte.wickham@posit.co>

- Add 'For example' sentence to all language Conditional Execution
  sections, making the HTML-format example explicit
- Repeat Conditional Execution section in the jupyter engine section
  of julia.qmd (it applied to both engines but was only under julia)
- Reword the when-meta/profiles paragraph in cross-references-divs.qmd
  to lead with the user intent rather than the mechanism
- Update _freeze/ hash and markdown for execution-options.qmd whose
  cached source hash was stale after the prior commit added the section

Documents when freeze updates are needed (any source change to a page
with executable code), the correct hash computation method, and a manual
update procedure for when quarto render cannot run in the local env.

# Conflicts:
#	.claude/rules/quarto-web-workflow.md

.githooks/check-freeze.sh: core logic verifying that any .qmd file with
a _freeze/ entry has a current hash (MD5 of LF-normalized source). Supports
commit mode (staged files) and push mode (commits ahead of upstream).

.githooks/pre-commit: git pre-commit hook calling the check; activate with
  git config core.hooksPath .githooks

.githooks/claude-hook.sh: Claude Code PreToolUse wrapper reading the Bash
tool input JSON from stdin and routing to check-freeze.sh.

.claude/settings.json: registers the hook for Bash tool calls, blocking
git commit and git push when a stale freeze is detected.

- Replace mapfile (bash 4+ only) with <<< heredoc, compatible with
  bash 3.2 (macOS system bash)
- Add md5_lf() wrapper: uses md5sum (Linux/Windows) or md5 -r (macOS)
- Redirect blocking message to stderr so Claude Code PreToolUse hook
  surfaces it correctly (tested on Windows Git Bash)

- Set all three .githooks/ scripts to 100755 so git runs them on
  Unix/macOS (non-executable hooks are silently ignored there)
- Read freeze JSON from git objects (staged index or HEAD) instead of
  working tree, avoiding false passes when the freeze file is updated
  on disk but not yet staged alongside the .qmd change
- Update _freeze/ check command in rule to `git diff HEAD -- _freeze/`
  so it shows both staged and unstaged changes (vs --stat which showed
  only unstaged, hiding already-staged freeze updates)