Salvaged from #49948 by @helix4u: every desktop cron API call
(list/get/runs/create/update/pause/resume/trigger/delete) now carries
profileScoped(), so global-remote mode routes the request to the profile
the UI is acting for instead of silently hitting the primary backend's
default profile.
* fix(desktop): stop contradicting the Ready pill with the one-time-install hint
When a provider's server-computed status is 'ready' (post_setup install
verifiably satisfied, e.g. cua-driver on PATH), the PostSetupRunner row
still said 'This backend needs a one-time install (…)'. Swap the copy for
a muted installed-confirmation one-liner and keep the Run setup button for
repair re-runs. Gated purely on the provider status prop so it composes
with the server-driven resting state work in the sibling lane.
* feat(tools): surface the web search/extract capability split in the Capabilities UI
The runtime has dispatched web_search and web_extract to independently
configurable backends for a long time (web.search_backend /
web.extract_backend overrides with web.backend as the shared fallback),
but the Capabilities tab still presented one monolithic 'Web Search &
Extract' choice that only wrote web.backend.
Backend:
- GET /api/tools/toolsets/web/config now returns active_search_backend /
active_extract_backend resolved via the REAL runtime getters
(tools.web_tools._get_search_backend/_get_extract_backend), plus each
provider row's web_backend key and supported capabilities (from the
registry's supports_search/supports_extract flags).
- PUT /api/tools/toolsets/web/provider accepts an optional capability
('search'|'extract') that writes web.<capability>_backend without
touching web.backend; validates the provider actually supports the
requested capability (ddgs/brave-free are search-only). Omitted →
unchanged legacy apply_provider_selection path.
- New tools_config.web_provider_capabilities() helper reads the plugin
registry's capability flags.
Frontend: 'Search: <backend>' / 'Extract: <backend>' pills above the web
provider matrix, per-row 'Search backend'/'Extract backend' assignment
pills, and 'Use for Search'/'Use for Extract' actions gated on each
backend's declared capabilities.
Tests: endpoint tests assert the runtime getters resolve to the written
backend (searxng for search, firecrawl for extract) after the endpoint
write; vitest covers badges, capability-gated buttons, and non-web
toolsets staying untouched.
* feat(desktop): deep-link Capabilities key rows to Settings → API Keys
Set env-var rows in the toolset config panel now offer 'Manage in API
Keys' in the row actions menu — an internal route change to
/settings?tab=keys&key=<ENV_KEY>. KeysSettings consumes the ?key= param
via the shared useDeepLinkHighlight hook (same mechanism as the command
palette's ?field= config deep links and ?session= archived-session
links): scrolls the credential card into view, flashes it, and expands
it. Applies generically to every env-var row, and only when the key is
set (unset keys are managed inline via Set). i18n in en/zh/zh-hant/ja.
* feat(desktop): point the vision Capabilities detail at Settings → Models
The vision toolset has no TOOL_CATEGORIES provider matrix — its
provider/model resolution runs through the auxiliary model config
(agent/auxiliary_client.py), so the Capabilities detail pane looked
empty with no hint of where the model choice lives.
Add a short explainer + an internal deep link
(/settings?tab=config:model&aux=vision) rendered only for
toolset.name === 'vision'. ModelSettings consumes the ?aux= param via
the shared useDeepLinkHighlight hook and scrolls/flashes the matching
auxiliary task row (rows now carry aux-task-<key> anchor ids). No
external URLs. i18n in en/zh/zh-hant/ja.
* test(desktop): use type-alias imports for the react-router mock (lint)
* chore: drop accidentally committed node_modules symlinks
* chore: drop remaining committed node_modules symlinks (apps/desktop, apps/shared)
The cron backend has always supported per-job model/provider pins (the
dashboard web UI and the cronjob tool expose them), but the desktop app's
cron editor had no way to set one — every job silently ran on the global
default model.
- Cron editor gains an optional Model select, grouped by provider, fed by
the same model.options catalog as the chat model picker (configured
providers with available models only, curated order preserved).
- Resetting to 'Default (global model)' clears a previous pin (model and
provider written as null); script-only (no_agent) jobs never touch the
model fields since the scheduler ignores overrides for them.
- A pinned model that has since left the catalog stays visible and
re-selectable instead of rendering Radix's blank trigger.
- Job detail pane shows the pinned model when one is set.
- ui/select grows SelectGroup + SelectLabel primitives for the grouped list.
- CronJob/CronJobCreatePayload/CronJobUpdates types carry model/provider;
en/ja/zh/zh-hant locales add the two new labels.
The cronjob model tool schema is intentionally unchanged — model selection
stays a user-facing UX affordance, not an agent-facing tool parameter.
* fix(windows): suppress console-window flash in tools post-setup subprocess spawns
The desktop GUI runs post-setup hooks via a detached, console-less
'hermes tools post-setup <key>' child (spawned with windows_detach_flags).
But the hook implementations in tools_config.py ran their inner installers
(npm install, agent-browser install, uv/pip installs, ensurepip, cua-driver
version probes and installer) without Windows creationflags — and on
Windows a console-less parent spawning a console/.cmd child materializes a
brand-new console window, the 'terminal flash' reported on the
Capabilities > Browser Automation setup journey.
Add _post_setup_no_window_flags(), a local wrapper around
windows_hide_flags() (CREATE_NO_WINDOW only — DETACHED_PROCESS would sever
stdio and break capture_output), and pass it at every post-setup subprocess
call site. Spawns that stream live output to the user's console
(verbose cua-driver install) only hide when stdout is not a tty, so
interactive CLI installs keep their output. POSIX behavior is unchanged
(the helper returns 0 off-Windows).
* fix(desktop): make Capabilities post-setup idempotent — Installed state instead of unconditional Run setup
The GUI panel rendered the primary 'Run setup' CTA whenever a provider
declared post_setup, ignoring the server-computed readiness status the
config endpoint already serves. Users on Windows clicked 'Run setup' on
an already-installed Local Browser and watched it 'install' again.
Frontend: PostSetupRunner now takes installed (provider.status === 'ready')
and renders an 'Installed' pill + small 'Re-run setup' text button in that
state; onComplete still refetches the toolset config, so a fresh install
flips the row to Installed once the endpoint reports ready.
Backend:
- _POST_SETUP_READY extended: agent_browser now tracks the FULL local
install (_local_browser_runnable: CLI + Chromium-or-Lightpanda) instead
of the bare CLI check; new entries for the cloud 'browserbase' hook
(CLI only — cloud rows host their own Chromium) and camofox (npm
package present).
- _run_post_setup prints distinct 'already installed, nothing to do'
messages for the agent-browser/Chromium/Camofox early-exits so the GUI
action log tells the truth on re-runs vs fresh installs.
i18n: new postSetupInstalled/postSetupRerun/postSetupInstalledHint strings
in en, ja, zh, zh-hant + types.
* fix(desktop): let managed Nous Subscription rows activate from the GUI via the Portal sign-in flow
PUT /api/tools/toolsets/{name}/provider intentionally skips the Nous
Portal auth gate the CLI runs inline (ensure_nous_portal_access) — but no
desktop surface handled it. Selecting 'Nous Subscription (Browser Use
cloud)' from Capabilities wrote browser.cloud_provider=browser-use +
use_gateway=true and then silently never activated: _is_provider_active
requires feature.managed_by_nous, which stays false without the
entitlement, and the credential was never used.
Backend: after apply_provider_selection, the endpoint now checks the
managed row's entitlement (get_nous_subscription_features force_fresh +
the same per-category coverage gate the CLI applies) and reports the gap
with additive response fields {needs_nous_auth: true, feature}. The
selection is still persisted — activation is what's gated.
Frontend: handleSelect surfaces a 'Sign in to Nous Portal' warning toast
with a Sign-in action instead of the misleading success toast. The action
drives the EXISTING Nous Portal OAuth device-code flow (provider id
'nous' in _OAUTH_PROVIDER_CATALOG): POST /api/providers/oauth/nous/start,
open verification_url, poll /poll/{session}; on approval the panel
refetches the toolset config so is_active/status flip.
i18n: nousAuthNeeded*/nousAuthSignIn/nousAuthDone*/nousAuthFailed strings
in en, ja, zh, zh-hant + types.
* feat(desktop): inherit project color on session rows
Sessions that belong to a colored project now pick up that color as the
sidebar row's idle lead dot, so work/personal/project buckets are legible
at a glance (Layer 1 of #66565). Derived from the same project membership
the sidebar already groups by; active states (working / needs-input /
background / unread) still own the dot so the tint never fights an
attention cue.
* feat(desktop): share session color across sidebar rows and pane tabs
Route session color through one computed store ($sessionColorById) that
both the sidebar rows and the pane tabs read, so a session and its tab can
never show different colors. Recomputed only when the session list or
projects change (cold atoms — the streaming pulse lives elsewhere) and read
as an O(1) lookup, never re-derived per render.
Tabs previously had no color at all: the strip renders only a title string.
Add a generic `accent` to the pane contribution that the tab strip paints as
a lead dot; the session tiles (via paneMirror) and the main workspace tab
(syncWorkspaceTitle) feed it from the same shared map. Precedence now lives
in one place, ready for per-session override / agent-set color (#66565).
* fix(desktop): resolve session color for repo-root-only sessions
liveSessionProjectId bailed the instant a session had no cwd, so an
older/imported session carrying only a git_repo_root — which the backend
still groups under its project — got no project and rendered a grey idle
dot instead of the project color ("grouped but grey"). Anchor on the repo
root when cwd is absent, matching how the sidebar grouped the row, and keep
the sibling-worktree guard for the cwd-present case.
Auto-detected git repos ("inherited" projects) have no projects.db row, so
their menu hid appearance/rename/etc. entirely and they could never be
themed. Add appearance to the auto-project menu: the first color/icon choice
adopts the repo as a real project (folder = repo root, name = its label)
carrying that look, after which it themes in place like any explicit
project. Routes both explicit and auto edits through one setProjectAppearance
helper; the picker closes on adopt so a stale second write can't double-create.
Replaces the dozen ad-hoc measure-*/profile-* scripts (each reinventing the
CDP client — 4 different copies — plus its own arg parsing, stats, output
path, and none with a baseline) with one framework under scripts/perf/:
- lib/cdp.mjs one CDP client + target discovery + typing + CPU-profile wrapper + DOM selectors
- lib/stats.mjs percentiles, histograms, CPU-profile self-time ranking
- lib/baseline.mjs load/compare/update baseline + regression gate (new capability)
- lib/launch.mjs attach, OR spawn a fully ISOLATED instance
- scenarios/* one module per measurement, registered in scenarios/index.mjs
- run.mjs / serve.mjs, baseline.json, README.md
Isolation solves the long-standing measurement blocker: a running `hgui` held
the Electron single-instance lock, so a second instance quit. `--spawn` /
`perf:serve` launch with their own --user-data-dir (separate lock scope), their
own HERMES_HOME (separate backend/sessions, config seeded from ~/.hermes so it
reaches a chat view without onboarding), and their own --remote-debugging-port.
Synthetic scenarios drive $messages via window.__PERF_DRIVE__, so no LLM credits.
Scenario -> sunset script mapping:
stream <- measure-synthetic-stream, profile-synth-stream, profile-long-stream
stream --real <- measure-real-stream, profile-real-stream
keystroke <- measure-latency, profile-typing, leak-typing
transcript <- (new: long-transcript mount cost)
submit <- measure-submit, measure-jump
session-switch <- profile-session-switch
profile-switch <- measure-profile-switch
CPU profiling is now a cross-cutting --cpuprofile flag, not 5 separate scripts.
CI-tier scenarios (stream, keystroke, transcript) need no backend/credits and
are gated against baseline.json (seed values; re-capture with --update-baseline
on a reference device). Backend-tier scenarios are report-only.
perf-probe.tsx gains loadTranscript() for the transcript scenario. No core
files touched; isolation is via CLI args, not env-gated app changes.
Verified: node --check all modules, tsc, eslint, and a unit smoke of the
stats + regression-gate logic. The end-to-end GUI run (which opens a window)
is left to run interactively via `npm run perf -- --spawn`.
Auto-detected git repos ("inherited" projects) have no projects.db row, so
their menu hid appearance/rename/etc. entirely and they could never be
themed. Add appearance to the auto-project menu: the first color/icon choice
adopts the repo as a real project (folder = repo root, name = its label)
carrying that look, after which it themes in place like any explicit
project. Routes both explicit and auto edits through one setProjectAppearance
helper; the picker closes on adopt so a stale second write can't double-create.
liveSessionProjectId bailed the instant a session had no cwd, so an
older/imported session carrying only a git_repo_root — which the backend
still groups under its project — got no project and rendered a grey idle
dot instead of the project color ("grouped but grey"). Anchor on the repo
root when cwd is absent, matching how the sidebar grouped the row, and keep
the sibling-worktree guard for the cwd-present case.
Follow-up to the salvaged #56724: the runtime's _generate_xai_tts reads
voice_id, language, speed, auto_speech_tags, optimize_streaming_latency,
sample_rate, and bit_rate — but never text_normalization, and the xAI
/v1/tts payload builder has no such field. Surfacing it in the desktop
GUI would be a dead knob, so remove it from DEFAULT_CONFIG, constants.ts
(labels/descriptions/SECTIONS), and the ja/zh/zh-hant locale catalogs.
The other six xAI keys are all verified against tools/tts_tool.py.
Consistent naming across the xAI TTS settings section. Speed and
sampleRate are shown only when xAI is the selected provider, so they
get the prefix too.
The Settings > Voice provider dropdowns (tts.provider / stt.provider) only offer
the built-in providers plus whatever value is currently set. Custom `type: command`
providers declared in config.yaml aren't selectable — and once you switch away from
one it drops off the list, so you can only return to it by hand-editing config.
enumOptionsFor now merges in the names of any `type: command` entries under the
tts/stt config sections, so local command-backed engines appear alongside the
built-ins and can be switched freely from the UI.
Enumeration mirrors the runtime's own resolution so the dropdown can only offer a
name the runtime would actually honour: the canonical `<section>.providers.<name>`
location plus the back-compat top-level `<section>.<name>` block, the optional
`type:` discriminator, and the built-in-name guard. The guard compares against the
runtime's built-in sets rather than the ENUM_OPTIONS display list, which is not a
substitute — it already omits `deepinfra` (TTS) and `deepinfra`/`local_command`
(STT), so a `providers.deepinfra` command block would otherwise be offered as
selectable while the runtime dispatches to the native backend instead.
- helpers.ts: add commandProviderNames() + the built-in guard; merge for
tts.provider + stt.provider
- helpers.test.ts: cover both sections, incl. that non-command config blocks
aren't offered and that built-ins absent from the display list are never
offered as command providers
* fix(desktop): compute truthful per-provider readiness for Capabilities tool config
Backend: GET /api/tools/toolsets/{name}/config now sends a per-provider
'status' field ('ready' | 'needs_keys' | 'needs_auth' | 'needs_setup')
computed by the new provider_readiness_status() in tools_config:
- env vars declared: all set -> ready, else needs_keys
- Nous-managed rows: Portal login + per-category tool-gateway entitlement
(MANAGED_FEATURE_COVERAGE_CATEGORY) -> ready, else needs_auth
- post_setup 'xai_grok' rows: Grok OAuth or XAI_API_KEY -> ready, else
needs_auth
- other keyless post_setup rows: installed-state predicate
(_POST_SETUP_READY: kittentts/piper/ddgs/langfuse via find_spec,
agent_browser via _has_agent_browser, cua_driver via PATH probe);
unknown hooks fall back to is_active as the setup-completed signal
- genuinely-free keyless rows (Edge TTS) stay ready
Existing fields are untouched; 'status' is additive so older desktops
keep working.
* fix(desktop): render server readiness status in Capabilities provider pills
The panel's providerConfigured() heuristic pilled every zero-env-var
provider 'Ready' — including logged-out Nous Subscription rows, xAI TTS
without Grok OAuth, and never-installed KittenTTS/Piper. Render the
backend's per-provider 'status' instead:
- ready -> existing 'Ready' pill
- needs_auth -> warn pill 'Needs sign-in'
- needs_setup -> warn pill 'Needs setup'
- needs_keys -> no pill (env-var fields are the signal)
Keyed rows keep deriving ready/needs_keys from local envState so saving
or clearing a key updates the pill without a refetch. Older backends
without 'status' fall back to the legacy env-var heuristic (narrow
compat path, desktop/runtime update on separate clocks).
Adds the warn tone to the settings Pill primitive and needsSignIn /
needsSetup strings to all locale catalogs (en, zh, zh-hant, ja).
Route session color through one computed store ($sessionColorById) that
both the sidebar rows and the pane tabs read, so a session and its tab can
never show different colors. Recomputed only when the session list or
projects change (cold atoms — the streaming pulse lives elsewhere) and read
as an O(1) lookup, never re-derived per render.
Tabs previously had no color at all: the strip renders only a title string.
Add a generic `accent` to the pane contribution that the tab strip paints as
a lead dot; the session tiles (via paneMirror) and the main workspace tab
(syncWorkspaceTitle) feed it from the same shared map. Precedence now lives
in one place, ready for per-session override / agent-set color (#66565).
Sessions that belong to a colored project now pick up that color as the
sidebar row's idle lead dot, so work/personal/project buckets are legible
at a glance (Layer 1 of #66565). Derived from the same project membership
the sidebar already groups by; active states (working / needs-input /
background / unread) still own the dot so the tint never fights an
attention cue.
Wire the scoped translator into the plugin context alongside storage/rest/
socket, and export usePluginI18n + the bundle types from @hermes/plugin-sdk.
The runtime shim re-exports the barrel automatically, so disk/third-party
plugins get the same door as bundled ones.
A plugin ships its own locale bundles and registers them under its id — never
editing core en.ts — exactly like ctx.storage namespaces persistence. The
registry merges repeated registrations and drops a plugin's bundles on
dispose (tracked by the loader like register/socket), resolving through the
shared translator: active locale -> the plugin's own en -> the raw key.
Two consumers, symmetric with core: usePluginI18n(id) for React UI
(re-renders on a locale switch or a late registration) and a module-level t
for handlers/stores.
Collapse the fallback walk out of `translateNow` into a single `translateFrom`
that takes a per-locale message source, so any translator (core catalog or a
plugin's bundles) reuses the exact dot-path walk, interpolation, and
active-locale/English/raw-key chain. Adds `getRuntimeI18nLocale`.
In the Focus layout `files` shares one tab group with `workspace`, so when the
first reply adopts a cwd the reactive files unhide fronted files and yanked the
active tab off the new session (~1s after the reply). #65375 fixed the sibling
"reactive unhide reopens a collapsed side" bug but frontPaneInGroup still stole
the active slot unconditionally.
Only take the active slot when the group's current active pane isn't itself
showable, so a reactive unhide can't steal focus from a pane the user is
viewing while still fronting a valid tab when nothing is shown.
Carries forward linfeng961's diagnosis + fix from #66870, reworked onto the
frontPaneInGroup path introduced by #65375.
Co-authored-by: linfeng961 <133505766+linfeng961@users.noreply.github.com>
* fix(desktop): don't auto-expand user-collapsed side on reactive unhide
When `setTreePaneHidden(paneId, false)` was called for a workspace-gated
pane like `files` (bound to $hasWorkspace), it auto-called
`revealTreePane(paneId)` — which expanded the parent column even when
the user had explicitly collapsed it via Cmd+J.
That meant every session create / resume — anything that flipped
$currentCwd from empty to non-empty — silently re-opened the right
sidebar and persisted that open state to localStorage, so the original
session also showed the sidebar as open on return.
`setTreePaneHidden` is a state primitive; user-intent semantics (open
the side, front the tab) belong to `revealTreePane`. Drop the auto-call
and replace it with a narrower `frontPaneInGroup` helper that only
makes the pane the active tab in its group — visible the next time the
column is opened, without forcing it open now.
* fix(desktop): preserve explicit review reveal
---------
Co-authored-by: David Metcalfe <80915+DavidMetcalfe@users.noreply.github.com>
A manual composer pick stays sticky across new chats (intended), but if that
model later disappears from the provider/config, every new chat kept trying the
dead model and 404'd. Fall back to the profile default in that one case only.
refreshCurrentModel now consults the model-options cache the composer already
populates (no extra fetch): a manual pick is preserved unless manualPickRemoved()
proves it's gone — provider present, non-empty catalog, model absent. An
unknown/absent provider, an empty (re-auth/unconfigured) list, or a not-yet-loaded
catalog all preserve the pick, so a still-valid selection is never clobbered.
Surface the session's first-class Project in both chat surfaces: the
Desktop status bar (project name as the workspace label, full cwd in the
tooltip) and the TUI status label + /status output.
One source of truth. The per-profile projects.db is the authority, read
in tui_gateway via _project_info_for_cwd (backed by
projects_db.project_for_path) and threaded through every session.info
emission path the TUI consumes. The Desktop already caches that truth in
$projectTree, so it DERIVES the label from it (projectNameForCwd) instead
of carrying a second per-session $currentProject atom fed from
session.info.
That drops the parallel state #64721 introduced and the entire
reset/reconciliation surface it required (resume, agentless cwd.set,
gateway-switch, fresh-draft): the label is purely derived, so it stays
correct whenever the cwd or the project tree changes. Only explicit,
named projects resolve on both surfaces, so an auto-discovered repo root
keeps the cwd-leaf label everywhere.
Excludes the unrelated markdown shell-fence change bundled in #64721.
The sidebar refresh fired three /api/profiles/sessions calls (recents, cron,
messaging), and each one reopened every selected profile's state.db and re-ran
list_sessions_rich + session_count — ~3N DB opens/counts per refresh, on every
turn/broadcast/reconnect.
Add GET /api/profiles/sessions/sidebar: one pass that opens each profile DB
once and runs the three source-scoped queries together (recents scoped to the
active profile; cron + messaging cross-profile), returning the three windows in
one payload. Same read-only projection, 300s active heuristic, and caller-
supplied source taxonomy (recents_exclude / messaging_exclude / source=cron) as
the per-slice endpoint.
Renderer refreshSessions now makes one listSidebarSessions call and distributes
recents/cron/messaging to their stores (cron *jobs* stay a separate getCronJobs
API). Electron splices remote profiles per slice via fetchProfilesSessionSlice
(reusing the proven per-slice merge) so remote correctness is preserved; the
no-remote common case gets the single-open fast path.
From the Desktop performance audit (P1: "Batch sidebar session slices").
Two structural fixes from the Desktop performance audit (P2 tier):
1. Scope live tool-diff subscriptions. `ToolEntry` subscribed to the whole
`$toolDiffs` map via `useStore`, so one `recordToolDiff` re-rendered every
mounted tool row. Add a cached per-toolCallId derived atom
(`$toolInlineDiff(id)`, mirroring the existing `$toolDisclosureOpen` pattern);
computed() only notifies when that id's diff string changes, so a live patch
re-renders one row.
2. Narrow profile / gateway-switch query invalidation. Both the active-profile
subscription and `wipeSessionListsForGatewaySwitch` called keyless
`queryClient.invalidateQueries()`, refetching account/marketplace/onboarding
caches on every switch. Add `invalidateProfileScopedQueries()` with a
denylist of profile-independent roots (billing, marketplace-themes,
onboarding-model-options, contrib-logs-tail). A denylist is correctness-safe:
a root we forget just refetches (cheap), whereas an allowlist that misses a
profile-scoped key would paint the previous profile's data.
Tests: per-tool notify isolation, and real-QueryClient invalidation partition
(profile-scoped invalidated, global left intact, unknown keys invalidated).
The char-level streaming fuzz runs 12 seeds × 500 growing prefixes
(~6000 full+cached lexes) and first trips the pre-fix boundary at
seed 11 / step 257, so the workload can't shrink without gutting the
guard. The work is bounded but exceeds Vitest's 5s per-test default on
CI workers under parallelism, so give this one test an explicit 30s
timeout instead of weakening coverage.
Built-in memory (MEMORY.md/USER.md) is controlled by memory_enabled, not
memory.provider — but the desktop dropdown offered 'builtin' as a normal
provider-plugin value and gave it plugin-shaped affordances (config panel,
OAuth connect row), and the empty sentinel rendered as '(none)' even though
built-in memory was active.
- Label the empty memory.provider option 'Built-in only' (all locales).
- Drop the literal 'builtin' option from the desktop ENUM_OPTIONS and the
backend config-schema select; _normalize_memory_provider_name already maps
legacy builtin/built-in/none values to ''. A stored legacy literal stays
visible via enumOptionsFor's current-value passthrough.
- Gate MemoryConnect and ProviderConfigPanel behind a new
isExternalMemoryProvider() helper so built-in aliases never get
provider-plugin affordances.
The streaming block splitter added in #67154 dropped only the previous
parse's trailing whitespace blocks plus its LAST content block before
re-lexing the appended suffix. That boundary is unsound: a trailing
Setext underline (`-`/`=`) underlines the paragraph ABOVE it, so
appending to it can retroactively merge the previous parse's last TWO
blocks into one.
Minimal repro: cached "…#e\n5\n-" lexes to [ …, "#e\n", "5\n-" ], but
grown to "…#e\n5\n-p2=kj:c" collapses "#e"/"5\n-" into a single block.
The reused settled prefix still contained a stale "#e\n" block. The
`blocks.join('') === text` guard can't detect this because the wrong
split reconstructs the same source string, so the divergence rendered
as mis-split blocks with no fallback.
Fix: drop the last TWO content blocks (skipping whitespace-only blocks
around them) before re-lexing the suffix. The block before the last is
the deepest an append can reach — a Setext underline consumes exactly
one preceding block — and earlier blocks stay fenced off by settled
blank lines, so re-lexing two is sufficient and safe.
Tests: a deterministic regression for the exact prev→grown pair, and a
character-level streaming property fuzz (12 seeds × 500 growing prefixes
over the markdown control alphabet). Both fail on the pre-fix boundary
and pass after. tsc/eslint/prettier clean; markdown-text suite green.
