file viewer: edit Markdown with optimistic-lock conflict detection
Nightly Build / build (push) Successful in 6m47s

- GET /api/file returns ETag (mtime+size) + X-Writable on disk files;
  PUT /api/file accepts optional if_match -> 409 Conflict on stale version
  (last-write-wins preserved when omitted), echoes the new ETag
- FileViewerBase: View | Edit tabs for .md when the caller can write;
  source textarea with Save/Cancel, live preview while editing
- Watcher no longer clobbers the buffer mid-edit: while editing with
  unsaved changes it probes the server ETag and only raises a conflict
  when the remote actually moved on (own-save echo is ignored)
- Conflict banner: Reload remote | Copy mine, then reload | Overwrite
- i18n (en/it/fr) + CSS; docs/projects.md updated
This commit is contained in:
2026-07-23 22:03:43 +01:00
parent 798e55951b
commit 3c52587dee
8 changed files with 446 additions and 9 deletions
+212 -3
View File
@@ -136,6 +136,14 @@ export class FileViewerBase extends LightElement {
_error: { state: true },
_compileError: { state: true },
_htmlMode: { state: true },
// ── Markdown source editor (View | Edit) ─────────────────────────────────
_mdMode: { state: true }, // 'view' | 'edit'
_editBuffer: { state: true }, // text being edited (diverges from _content when dirty)
_editDirty: { state: true }, // _editBuffer !== _content
_etag: { state: true }, // server version token (GET ETag) for optimistic locking
_canWrite: { state: true }, // caller may edit this path (X-Writable)
_conflict: { state: true }, // remote changed while editing — show the banner
_saving: { state: true },
};
constructor() {
@@ -148,6 +156,13 @@ export class FileViewerBase extends LightElement {
this._error = null;
this._compileError = null;
this._htmlMode = 'preview'; // HTML view: 'preview' (live iframe) | 'source'
this._mdMode = 'view'; // MD: 'view' (rendered) | 'edit' (source textarea)
this._editBuffer = '';
this._editDirty = false;
this._etag = null;
this._canWrite = false;
this._conflict = false;
this._saving = false;
this._watchPath = null; // path currently being watched (async-verified)
this._watchUnsub = null; // unsubscribe function returned by fileWatcher
this._reloadTimer = null; // debounce timer for change-triggered reloads
@@ -166,6 +181,10 @@ export class FileViewerBase extends LightElement {
_show(path) {
if (!path) return;
if (path === this._path && !this._error) return; // already loaded
// Guard unsaved edits when navigating to a different file: dropping them
// silently is the worse failure mode. (Accepted wrinkle: the hash has
// already moved; we don't fight the router here.)
if (this._editDirty && !confirm(t('fv.dirty_warn'))) return;
this._setupWatch(path);
this._load(path);
}
@@ -210,6 +229,12 @@ export class FileViewerBase extends LightElement {
this._error = null;
this._compileError = null;
this._htmlMode = 'preview';
this._mdMode = 'view';
this._editBuffer = '';
this._editDirty = false;
this._etag = null;
this._canWrite = false;
this._conflict = false;
this._revokeBlobUrl();
}
@@ -220,6 +245,11 @@ export class FileViewerBase extends LightElement {
this._content = '';
this._error = null;
this._compileError = null;
// Fresh load: drop any editor state from the previous file.
this._mdMode = 'view';
this._editDirty = false;
this._editBuffer = '';
this._conflict = false;
this._revokeBlobUrl();
this._loading = true;
} else {
@@ -243,8 +273,16 @@ export class FileViewerBase extends LightElement {
const res = await fetch(url);
if (!res.ok) throw new Error(`HTTP ${res.status}`);
this._content = await res.text();
// Optimistic-locking version token + write flag (editable surface).
this._etag = res.headers.get('ETag');
this._canWrite = res.headers.get('X-Writable') === '1';
}
// binary: nothing to fetch
// Keep the editor buffer glued to the content on any non-dirty load
// (initial load and silent external reloads while not editing). When the
// user is mid-edit with unsaved changes, the buffer is deliberately left
// alone — the watcher's _probeRemote path governs that case instead.
if (!this._editDirty) this._editBuffer = this._content;
} catch (e) {
this._error = e.message || String(e);
} finally {
@@ -326,16 +364,121 @@ export class FileViewerBase extends LightElement {
this._reloadTimer = setTimeout(() => {
this._reloadTimer = null;
const path = this._watchPath;
if (path) this._load(path, true);
if (!path) return;
// While editing with unsaved changes, never clobber the buffer. Instead
// probe the server for the current version: if it moved on from what we
// last knew, raise a conflict; if it matches (most often our own save
// echoing back), stay quiet.
if (this._mdMode === 'edit' && this._editDirty) {
this._probeRemote(path);
return;
}
this._load(path, true);
}, 300);
}
async _probeRemote(path) {
try {
const res = await fetch(`/api/file?path=${encodeURIComponent(path)}`);
const remote = res.headers.get('ETag');
if (remote && remote !== this._etag) this._conflict = true;
} catch { /* transient — the next change event retries */ }
}
// ── HTML preview/source toggle ──────────────────────────────────────────────
_toggleHtmlMode() {
this._htmlMode = this._htmlMode === 'preview' ? 'source' : 'preview';
}
// ── Markdown View | Edit ────────────────────────────────────────────────────
/** Switch the Markdown surface between rendered view and source editor. */
_setMdMode(mode) {
if (mode === this._mdMode) return;
if (mode === 'edit') {
// Entering edit: seed the buffer from the on-disk content (unless the
// user still has unsaved edits from a previous foray into Edit on this
// same file, which we preserve).
if (!this._editDirty) this._editBuffer = this._content;
}
this._mdMode = mode;
}
_onEditInput(e) {
this._editBuffer = e.target.value;
this._editDirty = this._editBuffer !== this._content;
}
/** Discard edits and return to the rendered view. */
_cancelEdit() {
if (this._editDirty && !confirm(t('fv.dirty_warn'))) return;
this._editBuffer = this._content;
this._editDirty = false;
this._conflict = false;
this._mdMode = 'view';
}
/**
* Persist the buffer. By default it sends `if_match` (optimistic locking): a
* `409` means the file changed remotely and we surface a conflict instead of
* overwriting. With `force=true` (the "Overwrite" button) it omits the token
* and clobbers whatever is on disk.
*/
async _save({ force = false } = {}) {
if (!this._path || this._saving) return;
this._saving = true;
try {
const payload = { path: this._path, content: this._editBuffer };
if (!force) payload.if_match = this._etag;
const res = await fetch('/api/file', {
method: 'PUT',
headers: { 'Content-Type': 'application/json' },
body: JSON.stringify(payload),
});
if (res.status === 409) {
// Remote moved on — keep the buffer, let the user decide via the banner.
this._conflict = true;
return;
}
if (!res.ok) throw new Error(await res.text());
// Success: adopt the new version token + the written content as the new
// baseline. The buffer stays equal to _content ⇒ no longer dirty.
const etag = res.headers.get('ETag');
if (etag) this._etag = etag;
this._content = this._editBuffer;
this._editDirty = false;
this._conflict = false;
} catch (e) {
this._error = e.message || String(e);
} finally {
this._saving = false;
}
}
/** Conflict resolution: reload the remote version, discarding local edits. */
async _reloadRemote() {
if (!this._path) return;
this._conflict = false;
this._editDirty = false;
await this._load(this._path, true);
this._editBuffer = this._content;
}
/** Conflict resolution: overwrite the remote with our buffer (no lock check). */
_overwrite() {
this._conflict = false;
this._save({ force: true });
}
/** Conflict resolution: copy our edits to the clipboard, then reload remote. */
async _copyMyChanges() {
try {
await navigator.clipboard.writeText(this._editBuffer);
} catch { /* clipboard may be blocked; the reload still proceeds */ }
await this._reloadRemote();
}
/**
* Header button that flips an HTML file between the live preview and its raw
* source. Returns `nothing` for every other kind, so subclasses can drop it
@@ -353,6 +496,45 @@ export class FileViewerBase extends LightElement {
</button>`;
}
/** View | Edit tab bar for Markdown. Only rendered when the caller can write. */
_renderMdTabs() {
const view = this._mdMode === 'view';
return html`<div class="fv-md-tabs" role="tablist">
<button class="fv-md-tab ${view ? 'active' : ''}" role="tab" aria-selected=${view}
@click=${() => this._setMdMode('view')}>${t('fv.tab_view')}</button>
<button class="fv-md-tab ${!view ? 'active' : ''}" role="tab" aria-selected=${!view}
@click=${() => this._setMdMode('edit')}>${t('fv.tab_edit')}</button>
${this._editDirty
? html`<span class="fv-md-dirty-dot" title=${t('fv.dirty_badge')}></span>`
: nothing}
</div>`;
}
/**
* The conflict banner: shown while editing when the file was modified
* remotely (another user / tab / agent) after our buffer diverged. Three
* escapes — reload remote (discard mine), overwrite (force my version), or
* copy mine to the clipboard before reloading.
*/
_renderConflictBanner() {
if (!this._conflict) return nothing;
return html`<div class="fv-conflict-banner" role="alert">
<i class="bi bi-exclamation-triangle-fill"></i>
<span class="fv-conflict-text">${t('fv.conflict_title')}</span>
<div class="fv-conflict-actions">
<button class="btn btn-sm btn-outline-secondary" @click=${() => this._reloadRemote()}>
${t('fv.conflict_reload')}
</button>
<button class="btn btn-sm btn-outline-secondary" @click=${() => this._copyMyChanges()}>
${t('fv.conflict_copy')}
</button>
<button class="btn btn-sm btn-warning" @click=${() => this._overwrite()}>
${t('fv.conflict_overwrite')}
</button>
</div>
</div>`;
}
// ── Body rendering (shared by both chromes) ─────────────────────────────────
_renderBody() {
@@ -410,8 +592,35 @@ export class FileViewerBase extends LightElement {
}
const ext = extOf(this._path);
if (ext === 'md' || ext === 'markdown') {
const rendered = rewriteMarkdownAssets(renderMarkdown(this._content), dirOf(this._path || ''));
return html`<div class="fv-md">${unsafeHTML(rendered)}</div>`;
const editing = this._mdMode === 'edit' && this._canWrite;
// In View we render the edits in flight too (when dirty), so toggling
// View/Edit is a live preview of what you're writing — not a flashback to
// the on-disk content.
const mdSrc = editing || this._editDirty ? this._editBuffer : this._content;
const rendered = rewriteMarkdownAssets(renderMarkdown(mdSrc), dirOf(this._path || ''));
return html`<div class="fv-md-wrap">
${this._canWrite ? this._renderMdTabs() : nothing}
${editing
? html`<div class="fv-edit">
${this._renderConflictBanner()}
<textarea class="fv-edit-textarea"
.value=${this._editBuffer}
spellcheck="false"
autocomplete="off"
autocapitalize="off"
placeholder=${t('fv.edit_placeholder')}
@input=${this._onEditInput}></textarea>
<div class="fv-edit-toolbar">
<button class="btn btn-sm btn-primary fv-edit-save"
?disabled=${!this._editDirty || this._saving}
@click=${() => this._save()}>${this._saving ? t('fv.saving') : t('fv.save')}</button>
<button class="btn btn-sm btn-outline-secondary"
@click=${() => this._cancelEdit()}>${t('fv.cancel')}</button>
<span class="fv-edit-hint">${t('fv.edit_hint')}</span>
</div>
</div>`
: html`<div class="fv-md">${unsafeHTML(rendered)}</div>`}
</div>`;
}
if (this._kind === 'latex') {
// Compile failed — show why, then fall back to the source.