[PATCH 0/9] Add support for an external command for fetching notes

Hi,

This series teaches the notes display machinery to obtain note text from a long-lived external helper configured by `notes.externalCommand`.

The motivation is mentioned in the main commit message (PATCH 7/9).

The helper protocol is intentionally narrow. Git starts the command once, sends one commit object ID per request, and expects either:

	<object-id> missing
	<object-id> ok <n>
	<n bytes of UTF-8 note text>

with the documented trailing newlines. The command is read only from protected configuration, so an untrusted repository cannot make ordinary note display run arbitrary commands. If the helper cannot be started, times out, exits, or sends an invalid response, Git warns once, disables it for the rest of the process, and continues without external notes.

Users can control from command line too with `--external-notes` and `--no-external-notes`. The semantics are close to `--notes=<ref>`: `--external-notes` implies naming an explicit notes source by itself, while `--external-notes --notes` combines it with the default notes refs, and `--external-notes --notes=<ref>` combines it with specific notes refs. The series also adds `notes.externalCommandName`, `notes.externalCommandTimeoutMs`, and the opt-in `notes.externalCommandForGrep` knob for installations that want external notes to participate in `--grep` matching.

Because this puts an external process on the log-formatting path, the series also adds the small support pieces needed to keep that boundary bounded: timeout/deadline variants of the read helpers, a timeout-aware command finisher, and cleanup that escalates if the helper does not exit promptly.

Testing: https://github.com/siddhpant/git/actions/runs/26107938855

Thanks, Siddh

Siddh Raman Pant (9):
  Documentation/git-range-diff: add missing notes options in synopsis
  notes: convert raw arg in format_display_notes() to bool
  wrapper: add sleep_nanosec
  run-command: add support for timeout in command finisher
  wrapper: add support for timeout and deadline in read helpers
  t3301: cover generic displayed notes behavior
  notes: support an external command to display notes
  Documentation: document external notes command options
  t: add tests for external notes command

 Documentation/config/notes.adoc             |  57 +++
 Documentation/git-format-patch.adoc         |  11 +-
 Documentation/git-range-diff.adoc           |   8 +-
 Documentation/pretty-options.adoc           |   9 +
 Makefile                                    |   2 +
 builtin/log.c                               |  17 +-
 builtin/name-rev.c                          |   9 +-
 builtin/range-diff.c                        |   2 +
 contrib/completion/git-completion.bash      |   4 +-
 log-tree.c                                  |  10 +-
 meson.build                                 |   1 +
 notes-external.c                            | 330 ++++++++++++++
 notes-external.h                            |  19 +
 notes.c                                     | 244 ++++++++---
 notes.h                                     |  32 +-
 revision.c                                  |  32 +-
 run-command.c                               |  92 +++-
 run-command.h                               |  13 +
 strbuf.c                                    |  26 +-
 strbuf.h                                    |   4 +
 t/helper/meson.build                        |   1 +
 t/helper/test-external-notes                |  64 +++
 t/helper/test-notes-external-config-reset.c |  20 +
 t/helper/test-tool.c                        |   1 +
 t/helper/test-tool.h                        |   1 +
 t/lib-notes.sh                              |  19 +
 t/t3206-range-diff.sh                       |  68 +++
 t/t3301-notes.sh                            | 461 ++++++++++++++++++++
 t/t6120-describe.sh                         |  17 +
 wrapper.c                                   | 188 +++++++-
 wrapper.h                                   |  24 +
 31 files changed, 1702 insertions(+), 84 deletions(-)
 create mode 100644 notes-external.c
 create mode 100644 notes-external.h
 create mode 100755 t/helper/test-external-notes
 create mode 100644 t/helper/test-notes-external-config-reset.c
 create mode 100644 t/lib-notes.sh