docs: research NVMe endurance signals

docs/research/nvme-endurance-signals.md

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+# NVMe endurance signals and projection constraints
+
+Research for [Verify NVMe endurance signals and projection constraints](https://git.bongbetic.com/xavierk/Fenris/issues/5).
+
+## Decision
+
+Fenris can defensibly project **when a host-write endurance baseline would be consumed if the observed usage habit continues**. It cannot predict SSD failure.
+
+Use lifetime **Data Units Written (DUW)** as the write counter, a model-and-capacity-specific **rated-TBW override** as the preferred baseline, and wall-clock observation history as the rate denominator. Keep **Percentage Used** as a separate manufacturer wear signal; only use it for a coarse, explicitly labeled implied baseline when no rated baseline exists. Treat **Power On Hours** as context, not elapsed calendar time. Express projection confidence as categorical evidence backed by visible facts, never as an accuracy percentage.
+
+This decision removes two unsupported assumptions in the current calculation: inferring endurance as `capacity × 600` when Percentage Used is zero, and presenting `DUW / Percentage Used` as non-estimated endurance ([current Fenris calculation](https://git.bongbetic.com/xavierk/Fenris/src/commit/91db519148a6359f6968b758a76ce30b480aaae0/fenris.py#L261-L270)).
+
+## What the NVMe signals support
+
+| Signal | Standard semantics and precision | Defensible Fenris use |
+|---|---|---|
+| **Percentage Used** | An unsigned one-byte, vendor-specific estimate based on actual use and the manufacturer's prediction of NVM life. `100` means estimated endurance consumed but may not mean subsystem failure; values may exceed 100, and values above 254 are represented as 255. It is updated once per power-on hour while the controller is not asleep ([NVM Express Base Specification 2.0e, SMART / Health Information](https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-2.0e-2024.07.29-Ratified.pdf); [official libnvme field documentation](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L88-L101)). | Preserve the raw integer. Do not clamp at 100; render 255 as `≥255%`, not an exact value. Do not call 100 a failure point. Zero is too coarse to establish zero wear or infer a baseline. |
+| **Data Units Written** | A 128-bit cumulative count of host-written 512-byte data units, excluding metadata, reported in thousands and rounded upward. For the NVM command set, Write logical blocks count; Write Uncorrectable and Write Zeroes do not. Zero means the counter is not reported ([official libnvme structure and semantics](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L15-L23), [field definition](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L122-L138)). | Store the raw integer and derive `reported_host_bytes = DUW × 512,000`. Call it **reported host writes**, not physical NAND writes or exact bytes. Treat zero as unsupported/ambiguous unless later positive samples prove support. |
+| **Power On Hours** | Integer power-on hours; the controller may omit time powered in a non-operational power state ([official libnvme field definition](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L159-L162)). | Display as drive context and use changes as a diagnostic. Do not use it as exact active time, idle time, powered-off time, or the denominator of a calendar-life projection. |
+
+The SMART / Health log describes controller-level lifetime information; Fenris should therefore bind a history segment to a stable controller identity and avoid implying filesystem-level or physical-NAND-write precision ([NVM Express Base Specification 2.0e](https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-2.0e-2024.07.29-Ratified.pdf)).
+
+### DUW quantization
+
+Let `q = 512,000 bytes`, raw counter `U_t`, and reported cumulative host writes `W_t = qU_t`. Since each cumulative endpoint is rounded upward, the reported interval delta is:
+
+```text
+ΔW = q(U_b - U_a)
+```
+
+Its error from endpoint quantization alone is less than one quantum: `|ΔW - actual interval writes| < 512,000 bytes`. Thus a zero hourly delta does not prove no writes below that resolution, and “exact bytes written” is not defensible. This bound follows directly from the standard's upward-rounded cumulative representation ([official libnvme DUW definition](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L122-L138)).
+
+## Endurance baseline precedence
+
+Use these sources in order:
+
+1. **Verified rated-TBW override** for the exact manufacturer, model, and capacity, with source URL and document revision.
+2. **Unverified manual override**, visibly labeled as user-supplied.
+3. **Implied endurance from Percentage Used**, visibly labeled as a coarse heuristic.
+4. Otherwise, **projection unavailable**. Never synthesize TBW from capacity alone.
+
+Manufacturer TBW values are model- and capacity-specific: Samsung, for example, rates the 1 TB 990 PRO at 600 TBW and the 2 TB model at 1,200 TBW, and states that its warranty is limited by the stated period or TBW, whichever comes first ([Samsung 990 PRO data sheet, pp. 3–4](https://download.semiconductor.samsung.com/resources/data-sheet/Samsung_NVMe_SSD_990_PRO_Datasheet_Rev.1.0.pdf)). Samsung's warranty treats crossing TBW as a warranty-limit condition, not as a predicted failure event ([Samsung SSD Limited Warranty, sections A–B](https://download.semiconductor.samsung.com/resources/warranty/SAMSUNG_SSD_Limited_Warranty_English_US.pdf)). Fenris must therefore call rated TBW an endurance/warranty baseline rather than physical end of life.
+
+Store an override as bytes plus provenance. If the input is labeled TBW, define it explicitly as decimal terabytes:
+
+```text
+E_rated = entered_TBW × 10^12 bytes
+R_rated = max(E_rated - W_t, 0)
+```
+
+Keep rated-budget consumption and manufacturer Percentage Used separate; disagreement is useful evidence, not a reason to blend them into a fabricated wear percentage.
+
+### Implied endurance constraints
+
+Only for `1 ≤ p ≤ 254`:
+
+```text
+E_implied = 100W_t / p
+R_implied = max(E_implied - W_t, 0)
+```
+
+This assumes the vendor's Percentage Used estimate is proportional to host writes, which NVMe does **not** require: the field is explicitly vendor-specific and based on the manufacturer's life prediction ([NVM Express Base Specification 2.0e](https://nvmexpress.org/wp-content/uploads/NVM-Express-Base-Specification-2.0e-2024.07.29-Ratified.pdf); [libnvme documentation](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L88-L101)). Do not compute it for 0 or saturated 255. Label it **implied from vendor wear estimate**, show few significant digits, and do not promote it until multiple wear increments make the estimate less dominated by one-percentage-point quantization. At low values it is intrinsically unstable: changing `p` from 1 to 2 halves the result.
+
+## Usage-adjusted projection
+
+For a selected valid wall-clock history interval from `a` to `b`:
+
+```text
+rate = q(U_b - U_a) / elapsed_wall_clock_seconds
+projected_seconds = remaining_baseline_bytes / rate   (rate > 0)
+```
+
+If the rate is zero, report **no finite projection from this history**, not infinity. Required wording should be equivalent to:
+
+> Estimated time until the selected host-write endurance baseline is consumed, if future write usage resembles the observed usage habit. This is not a predicted hardware-failure date.
+
+Use wall-clock elapsed time because powered-off and idle periods are part of the observed usage habit, whereas Power On Hours may exclude non-operational powered states ([libnvme Power On Hours definition](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L159-L162)). Deliberately disabled monitoring must be excluded or marked unknown by lifecycle records; a SMART counter pair can recover aggregate writes across a collector gap but cannot reveal when within that gap the writes occurred.
+
+## History and changing habits
+
+Persist interval observations rather than pretending every delta belongs to a clock-hour bucket:
+
+- Compute deltas only within one controller-identity segment and only when DUW is monotonic. A decrease is a segment boundary or data fault, never a delta to clamp to zero.
+- Preserve both endpoints, elapsed wall time, counter delta, and gap/monitoring state. Writes across a gap cannot be assigned exactly to individual hours; any proportional allocation must be labeled estimated.
+- Use daily aggregates for habit evidence and retain hourly intervals for display/diagnostics. Hourly samples are time-dependent, so raw sample count is not independent evidence; NIST warns that autocorrelation can invalidate standard `s/√N` uncertainty calculations and other statistical conclusions ([NIST Autocorrelation Plot](https://www.itl.nist.gov/div898/handbook/eda/section3/eda331.htm)).
+- Compare descriptive recent, medium, and longer horizons (for example 7, 28, and 90 days) and expose their projection spread as a **scenario range**, not a statistical confidence interval.
+- Flag a changing habit when recent and earlier daily-rate windows diverge materially for a sustained period. Prefer the recent sustained regime for the headline projection while retaining the older regime as comparison. This is necessary because a stationary time series has stable mean, variance, and autocorrelation structure; trend, changing variance, and seasonality violate that assumption ([NIST Stationarity](https://www.itl.nist.gov/div898/handbook/pmc/section4/pmc442.htm)).
+- Before treating days as interchangeable, account for weekly or other periodic patterns; NIST describes seasonality as regular periodic behavior that must be addressed in a time-series model ([NIST Seasonality](https://www.itl.nist.gov/div898/handbook/pmc/section4/pmc443.htm)).
+
+Exact horizon lengths and change thresholds are product guardrails to validate later, not statistically guaranteed constants.
+
+## Projection confidence
+
+Use four categorical states:
+
+- **Unavailable** — no applicable baseline, unsupported DUW, identity/counter discontinuity, or no positive usable rate.
+- **Warming up** — too little history to represent ordinary usage cycles.
+- **Limited evidence** — implied or unverified baseline, short/incomplete history, substantial horizon spread, stale observations, or a recent habit change.
+- **Supported evidence** — verified baseline, multiple representative usage cycles, good interval coverage, current observations, and stable rates across relevant horizons.
+
+Always show the contributing facts, for example:
+
+> Supported evidence · verified manufacturer TBW · 42 calendar days · 96% interval coverage · 6 weekly cycles · recent and 28-day rates agree
+
+Do not display “82% confidence” or “95% accurate.” NIST defines confidence level through the long-run coverage of an interval procedure, not as the probability that this particular estimate is correct ([NIST Confidence Limits](https://www.itl.nist.gov/div898/handbook/eda/section3/eda352.htm)). A future statistical rate interval would cover rate-estimation uncertainty only; it would not validate the endurance baseline or guarantee that habits remain unchanged.
+
+## Required disclosures
+
+1. This is an endurance projection, not a predicted hardware-failure date.
+2. Percentage Used is vendor-specific; 100 means estimated endurance consumed but may not mean failure, it can exceed 100, and 255 is saturated ([NVMe definition](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L88-L101)).
+3. Rated TBW can be a warranty/endurance threshold with separate time and eligibility terms, not a failure threshold ([Samsung warranty](https://download.semiconductor.samsung.com/resources/warranty/SAMSUNG_SSD_Limited_Warranty_English_US.pdf)).
+4. DUW is upward-rounded host writes excluding metadata and selected commands, not exact physical NAND writes ([NVMe definition](https://github.com/linux-nvme/libnvme/blob/ad61ac8a319ad0823c1c9861eecbf66125f8b9a1/doc/man/nvme_smart_log.2#L122-L138)).
+5. Projection quality depends on baseline provenance, history duration and completeness, recentness, stability, and representative usage cycles; future workload and firmware behavior remain outside the observed evidence.
+6. Gaps can preserve an aggregate counter delta without preserving hourly timing; unexplained and deliberately disabled periods must be distinguished.
+
+## Newly surfaced questions
+
+Carry these to the next Wayfinder session rather than expanding this ticket:
+
+- Should rated-budget and manufacturer Percentage Used projections appear side by side when they disagree?
+- Which provenance fields are mandatory for a TBW override: URL, revision, model, capacity, region, and entry date?
+- What exact warming-up, coverage, horizon, and changing-habit thresholds should the projection-model specification adopt?
+- How should powered-off periods, deliberately disabled monitoring, and unexplained gaps be represented separately?
+- Which stable controller identity prevents observation history from crossing a drive replacement?
+- Should a detected recent regime automatically replace the long-term rate or require acknowledgement?
+- Should the TUI expose multi-horizon scenarios only, or also a model-based statistical rate interval?
+- How should unsupported DUW, saturated Percentage Used, and counter discontinuities appear in the TUI?

docs/research/python-tui-frameworks.md

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-# Python TUI frameworks for Fenris
-
-_Research snapshot: 2026-08-31. Planning only; no product implementation._
-
-## Decision
-
-Use **Textual** for Fenris's later TUI prototype and, if the prototype checks below pass, for the persistent TUI.
-
-Textual is the best fit for Fenris's keyboard-first Overview, Usage History, Drive Health, and Settings views because one framework supplies flexible grid/horizontal/vertical layouts, dashboard and form widgets, background workers, and a headless interaction driver ([layout](https://textual.textualize.io/guide/layout/), [widget gallery](https://textual.textualize.io/widget_gallery/), [workers](https://textual.textualize.io/guide/workers/), [testing](https://textual.textualize.io/guide/testing/)). Its principal costs are the largest direct dependency set in this shortlist and only a compact `Sparkline` as built-in charting; detailed historical plots would need a custom widget or the first-party `textual-plotext` integration ([PyPI metadata](https://pypi.org/pypi/textual/json), [Sparkline](https://textual.textualize.io/widgets/sparkline/), [`textual-plotext`](https://github.com/Textualize/textual-plotext)).
-
-This recommendation is **conditional on raising Fenris's Python floor from its currently documented Python 3.7+ to Python 3.9+**: Textual 8.2.8 and Urwid 4.0.13 require Python 3.9+, while prompt_toolkit 3.0.53 requires Python 3.10+ ([Fenris README](../../README.md#you-need), [Textual metadata](https://pypi.org/pypi/textual/json), [Urwid metadata](https://pypi.org/pypi/urwid/json), [prompt_toolkit metadata](https://pypi.org/pypi/prompt-toolkit/json)). If retaining Python 3.7 is mandatory, none of the current versions evaluated here qualifies.
-
-**Fallback:** choose **Urwid** if prototype evidence shows that explicit low-level terminal/display control or a smaller direct dependency set matters more than Textual's higher-level layouts, forms, workers, and test driver ([display modules](https://urwid.org/manual/displaymodules.html), [package metadata](https://pypi.org/pypi/urwid/json)).
-
-## Scope and method
-
-The shortlist covers maintained, full-screen-capable Python projects with first-party application/widget documentation: Textual, Urwid, and prompt_toolkit. The evaluation uses official documentation, repository release APIs, and PyPI package metadata. Versions, Python floors, dependencies, and release activity are a point-in-time snapshot and should be rechecked when dependencies are locked.
-
-## Comparison
-
-| Criterion | Textual 8.2.8 | Urwid 4.0.13 | prompt_toolkit 3.0.53 |
-|---|---|---|---|
-| **Terminal compatibility** | PyPI classifies Linux, macOS, and Windows 10/11 support; this exceeds Fenris's Linux-only scope ([metadata](https://pypi.org/pypi/textual/json)). | Offers pure-Python raw and OS curses displays. The manual compares UTF-8, color, mouse, and external-event-loop capabilities; curses is described as broadly terminal-compatible, while raw supports 88/256/24-bit color and external loops ([display modules](https://urwid.org/manual/displaymodules.html)). | Provides full-screen applications and platform-specific POSIX/Windows test input; official input docs describe cross-platform one-key-at-a-time input and Windows behavior ([full-screen apps](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/full_screen_apps.html), [input](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/asking_for_input.html), [testing](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/advanced_topics/unit_testing.html)). |
-| **Responsive layout** | Vertical, horizontal, and grid layouts support fractional, percentage, and automatic sizing, nesting, spans, overflow, docking, and runtime layout changes ([layout](https://textual.textualize.io/guide/layout/)). | `Pile`, `Columns`, `GridFlow`, `Overlay`, `ListBox`, padding, and flow/box/fixed sizing provide procedural composition ([widgets](https://urwid.org/manual/widgets.html)). | `VSplit`, `HSplit`, `FloatContainer`, `ConditionalContainer`, and scrollable panes compose full-screen regions, but the reviewed guide does not document breakpoint-style responsiveness ([full-screen apps](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/full_screen_apps.html)). |
-| **Dashboard, charts, history** | Built-ins include `DataTable`, `ProgressBar`, `Digits`, and `Sparkline`; Sparkline summarizes reactive numerical data into bars according to available widget width ([gallery](https://textual.textualize.io/widget_gallery/), [Sparkline](https://textual.textualize.io/widgets/sparkline/)). `textual-plotext` adds a `PlotextPlot` wrapper for richer plotting ([repository](https://github.com/Textualize/textual-plotext)). | Includes `BarGraph`, `GraphVScale`, and `ProgressBar`; richer history views still require composition or custom rendering ([graph widgets](https://urwid.org/reference/widget.html#graph-widgets)). | The documented reusable widget set supports text areas, buttons, frames, dialogs, and menus, but does not list a chart widget; Fenris charts would therefore be custom controls/rendering ([widget reference](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/reference.html#module-prompt_toolkit.widgets)). |
-| **Forms and keyboard use** | Built-ins include `Input`, `MaskedInput`, `Select`, checkbox/radio/selection controls, switches, buttons, and text areas ([gallery](https://textual.textualize.io/widget_gallery/)). `Input` supports validation on change, blur, or submit and emits results with its messages ([Input](https://textual.textualize.io/widgets/input/)). | Supplies `Edit`, `Button`, `CheckBox`, `RadioButton`, focus handling, and keyboard/mouse event support; application code owns more form orchestration ([widgets](https://urwid.org/manual/widgets.html)). | Strong key-binding, editing, completion, history, suggestion, and validation facilities; full-screen reusable components include `TextArea` and `Button` ([input](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/asking_for_input.html), [full-screen apps](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/full_screen_apps.html)). |
-| **Async/background updates** | Async workers run coroutines concurrently; thread workers cover blocking APIs. Workers support cancellation and exclusivity, while thread-originated UI updates use `call_from_thread()` or thread-safe messages ([workers](https://textual.textualize.io/guide/workers/)). | Supports Select, asyncio, Twisted, GLib, Tornado, and ZMQ event loops plus alarms and watched files; executor use varies by loop ([main loop](https://urwid.org/manual/mainloop.html)). | Uses asyncio natively and supports `Application.run_async()` inside an existing event loop ([asyncio](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/advanced_topics/asyncio.html)). |
-| **Testability** | `App.run_test()` runs headlessly and returns a `Pilot` that can press keys, click, wait for queued messages, and run at specified terminal sizes ([testing](https://textual.textualize.io/guide/testing/)). | The public manuals reviewed do not expose a comparable application pilot; tests would be built around widgets, rendering, callbacks, and event-loop seams ([widgets](https://urwid.org/manual/widgets.html), [main loop](https://urwid.org/manual/mainloop.html)). | Official testing guidance supplies platform-specific pipe input, `DummyOutput`, and app sessions for asserting results or data changes, while warning against brittle stdout-byte assertions ([unit testing](https://python-prompt-toolkit.readthedocs.io/en/stable/pages/advanced_topics/unit_testing.html)). |
-| **Direct dependency cost** | Five required distributions: `markdown-it-py[linkify]`, `mdit-py-plugins`, `platformdirs`, `pygments`, and `rich`; syntax-tree packages are optional-extra dependencies ([metadata](https://pypi.org/pypi/textual/json)). | Two required distributions: `wcwidth` and `typing-extensions`; curses, GLib, Tornado, Trio, Twisted, ZMQ, serial, and LCD integrations are optional extras ([metadata](https://pypi.org/pypi/urwid/json)). | One required distribution: `wcwidth` ([metadata](https://pypi.org/pypi/prompt-toolkit/json)). |
-| **Python floor** | `>=3.9,<4.0` ([metadata](https://pypi.org/pypi/textual/json)). | `>=3.9.0` ([metadata](https://pypi.org/pypi/urwid/json)). | `>=3.10` ([metadata](https://pypi.org/pypi/prompt-toolkit/json)). |
-| **Project health signal** | Five non-draft releases from 8.2.4 through 8.2.8 were published between 2026-04-19 and 2026-06-30 ([release API](https://api.github.com/repos/Textualize/textual/releases?per_page=5)). | Five releases from 4.0.9 through 4.0.13 were published between 2026-08-14 and 2026-08-25 ([release API](https://api.github.com/repos/urwid/urwid/releases?per_page=5)). | Release 3.0.53 was published 2026-07-26, following 3.0.52 on 2025-08-27 ([release API](https://api.github.com/repos/prompt-toolkit/python-prompt-toolkit/releases?per_page=5)). |
-
-All three show recent release activity, so maintenance does not eliminate a candidate. Textual wins on integrated application-level capabilities rather than on release recency alone.
-
-## Fit to the four views
-
-- **Overview:** use Textual layout containers with `Digits`, labels, progress indicators, and compact sparklines for monitoring status, usage-adjusted theoretical lifespan, projection confidence, and recent activity ([layout](https://textual.textualize.io/guide/layout/), [gallery](https://textual.textualize.io/widget_gallery/)).
-- **Usage History:** prototype a `DataTable` plus `Sparkline` first. Add `textual-plotext` only if user testing establishes a need for axes, multiple series, or richer plots, keeping plotting out of the core dependency decision until then ([DataTable](https://textual.textualize.io/widgets/data_table/), [Sparkline](https://textual.textualize.io/widgets/sparkline/), [`textual-plotext`](https://github.com/Textualize/textual-plotext)).
-- **Drive Health:** use a table and status/progress widgets for NVMe attributes; wording must continue to distinguish endurance projection from a hardware-failure prediction ([gallery](https://textual.textualize.io/widget_gallery/), [parent-map destination and terminology](https://git.bongbetic.com/xavierk/Fenris/issues/1)).
-- **Settings:** Textual's selection, boolean, and validated text-entry controls cover a keyboard-only form without inventing controls ([gallery](https://textual.textualize.io/widget_gallery/), [Input validation](https://textual.textualize.io/widgets/input/)).
-
-The TUI should consume snapshots from the independent collector rather than run NVMe collection in its UI loop; the ticket's parent map makes that independent-collector architecture part of the destination ([parent map](https://git.bongbetic.com/xavierk/Fenris/issues/1)). Textual workers remain useful for non-blocking database/IPC reads and cancellable refreshes ([workers](https://textual.textualize.io/guide/workers/)).
-
-## Prototype acceptance checks
-
-The later prototype should verify:
-
-1. Complete keyboard-only operation and predictable focus order across all four views.
-2. Reflow or deliberate scrolling at 80×24 and a representative wide terminal; Textual's test runner accepts explicit terminal sizes ([testing](https://textual.textualize.io/guide/testing/)).
-3. Smooth refresh while database/IPC reads are delayed, plus clean cancellation and shutdown ([workers](https://textual.textualize.io/guide/workers/)).
-4. Headless tests for view switching, settings validation, stale/error states, and collector disappearance ([testing](https://textual.textualize.io/guide/testing/), [Input](https://textual.textualize.io/widgets/input/)).
-5. Readable behavior in the actual Linux terminal matrix, including SSH and tmux/screen if those are required; framework platform labels alone do not establish every terminal's behavior.
-6. Usage History performance with realistic observation volume and gaps.
-7. A table/text equivalent for every chart so observation gaps and projection confidence are not encoded by color or graphics alone.
-8. Installation with Fenris's chosen packaging mechanism and the agreed Python floor.
-
-## Newly surfaced questions
-
-Do not open follow-up tickets during this research resolution; carry these into the next Wayfinder session:
-
-- May the redesign raise Fenris's minimum Python version from 3.7 to 3.9?
-- What is the minimum supported terminal contract: modern color terminals only, or also Linux virtual console, monochrome/16-color, SSH, tmux, and screen?
-- Is a table plus sparkline sufficient for Usage History, or are axes, multiple series, zoom, and interval selection required?
-- Should richer plotting be an optional install extra?
-- What is the small-terminal policy: reflow, hide secondary content, scroll, or reject below a documented size?
-- Which accessibility targets are required, including screen readers, reduced color, high contrast, and reduced animation?
-- Does the TUI read observation storage directly or use an IPC snapshot API from the collector?
-- Which settings are user-owned versus system/collector-owned, and which changes require privilege escalation?
-- Are semantic interaction assertions sufficient, or are deterministic visual snapshots also required?