fd1210e557
Complete task002 through task016 across cache correctness, editor lifecycle, C boundaries, build and release governance, dictionary provenance, performance, interactive workflows, tests, documentation, and final cleanup.
57 lines
2.1 KiB
Markdown
57 lines
2.1 KiB
Markdown
# Serialize a Logical Copy Instead of Restoring After Save
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## Context
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EKP previously unformatted the display buffer in `before-save-hook` and
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reformatted it in `after-save-hook`. Emacs does not run `after-save-hook`
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when writing fails or is interrupted, so the screen stayed unformatted and
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the marker state stayed live.
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## Decision
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Do not mutate the source buffer during save. A buffer-local
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`write-region-annotate-functions` entry switches whole-buffer writes to a
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hidden logical copy. This is the same documented buffer-switch boundary used
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by Emacs format encoders, so normal backup, coding, file-mode, VC, and later
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annotation behavior remains owned by Emacs.
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## Alternatives Rejected
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### Add another restoration hook
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There is no general failure hook paired with `after-save-hook`. A
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post-command fallback would miss programmatic saves and nested calls.
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### Advise `save-buffer` or `write-region` globally
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Global advice would make every Emacs save share EKP's lifecycle and create
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ordering conflicts with other packages.
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### Reimplement saving in `write-contents-functions`
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Owning the actual write would duplicate backup, coding, file modes, VC, and
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visited-file semantics that Emacs already implements.
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## Consequences
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- Success and failure paths leave the visible layout byte-identical.
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- Disk and auto-save output receive logical text.
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- A successful write disposes the copy immediately.
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- Because Emacs does not call the post-annotation function after a failed
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write, at most one hidden copy remains per source buffer; retry or teardown
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replaces and clears it.
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- No global advice, external dependency, or saved-file format changed.
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## Verification
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The old model failed real missing-directory and forced-quit tests by leaving
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the logical text visible. The new model passes success, filesystem failure,
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encoding failure plus retry, and interruption tests. Full ERT passes
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102/102, C/Elisp fuzz passes 300/300, and warnings-as-errors byte compilation
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plus checkdoc are clean.
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## Rollback
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Restore the before/after hooks and their marker state. Existing files need
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no migration because both designs write the same logical bytes.
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