feat(telemetry): Client-Side Deep Module TelemetryEngine & Frontend Test Harness (Phase 2) #16

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opened 2026-09-09 16:22:09 +00:00 by gabogg · 3 comments
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PR #13: docs(ui): industrial brutalist frontend redesign and tactical telemetry guidelines

What to build

Deliver the unified client-side telemetry ingestion engine (TelemetryEngine) that absorbs server clock-skew smoothing, open-door duration timers, active alarm priority hoisting, and Little's Law dwell ratio calculations, emitting immutable TelemetrySnapshot instances over a 1 Hz temporal loop via subscribe(listener).

Encapsulates both live network transport and fixture playback for offline testing, backed by a Node 22 native test runner integrated directly into pytest.

Acceptance criteria

  • TelemetryEngine module created in app/static/js/src/telemetry/telemetry_engine.js with a clean deep module consumption interface (subscribe, start, stop, getSnapshot).
  • Dual-transport hydration seam implemented: LiveNetworkTransport (initial HTTP bootstrap + WebSocket reconnection) and FixtureTransport (in-memory snapshot injection).
  • Domain metrics derived internally: smoothed clock skew delta (\Delta t), open-door elapsed timers, active alarm priority hoisting, and dwell envelope ratio ({\max}$).
  • Master 1 Hz / requestAnimationFrame temporal loop emitting immutable snapshots to all registered subscribers.
  • Unit test suite in tests/frontend/test_telemetry_engine.test.js testing clock-skew smoothing, snapshot immutability, alarm ordering, and timer cadence via Node 22 native runner (node:test, node:assert).
  • Python test wrapper in tests/test_frontend_modules.py executing the frontend test suite so that running pytest remains the single 100% green repository gate.

Blocked by

  • #15 (feat(ui): Air-Gapped Asset Vendoring & Tactical CSS Design System (Phase 1))
## Parent [PR #13: docs(ui): industrial brutalist frontend redesign and tactical telemetry guidelines](https://git.gaboggamer.online/gabogg/hikcentral/pulls/13) ## What to build Deliver the unified client-side telemetry ingestion engine (`TelemetryEngine`) that absorbs server clock-skew smoothing, open-door duration timers, active alarm priority hoisting, and Little's Law dwell ratio calculations, emitting immutable `TelemetrySnapshot` instances over a 1 Hz temporal loop via `subscribe(listener)`. Encapsulates both live network transport and fixture playback for offline testing, backed by a Node 22 native test runner integrated directly into `pytest`. ## Acceptance criteria - [ ] `TelemetryEngine` module created in `app/static/js/src/telemetry/telemetry_engine.js` with a clean deep module consumption interface (`subscribe`, `start`, `stop`, `getSnapshot`). - [ ] Dual-transport hydration seam implemented: `LiveNetworkTransport` (initial HTTP bootstrap + WebSocket reconnection) and `FixtureTransport` (in-memory snapshot injection). - [ ] Domain metrics derived internally: smoothed clock skew delta ($\Delta t$), open-door elapsed timers, active alarm priority hoisting, and dwell envelope ratio ({\max}$). - [ ] Master 1 Hz / `requestAnimationFrame` temporal loop emitting immutable snapshots to all registered subscribers. - [ ] Unit test suite in `tests/frontend/test_telemetry_engine.test.js` testing clock-skew smoothing, snapshot immutability, alarm ordering, and timer cadence via Node 22 native runner (`node:test`, `node:assert`). - [ ] Python test wrapper in `tests/test_frontend_modules.py` executing the frontend test suite so that running `pytest` remains the single 100% green repository gate. ## Blocked by - #15 (feat(ui): Air-Gapped Asset Vendoring & Tactical CSS Design System (Phase 1))
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📋 Tech Debt Carried Forward from Issue #15 Code Review

The following items were identified during the #15 code review and should be addressed as prefactoring at the start of this ticket:

1. Extract TacticalStaticFiles out of main.py (~15 min)

app/main.py is the app bootstrap + exception handlers + router mounts. The TacticalStaticFiles cache-policy subclass (L112-143) causes Divergent Change: main.py now changes for two unrelated reasons. Extract to app/middleware/static.py or similar.

2. Harden air-gap test with xfail assertions (~5 min)

test_index_html_air_gapped_vendor_references asserts cdn.jsdelivr.net/npm/hls.js is absent but does not assert that cdn.tailwindcss.com and cdnjs.cloudflare.com are absent. Add assertions for both with pytest.mark.xfail(reason="CDN removal deferred to Phase 5 / Issue #19") so the known gap is visible and tracked, not silently passing.

3. Scope the default cache fallback (~5 min)

TacticalStaticFiles.file_response includes a blanket Cache-Control: public, max-age=86400 catch-all for all non-CSS/JS/font/vendor files (L141). The #15 spec only asked for cache directives for fonts, scripts, and tactical styles. Either remove the catch-all or explicitly document it as intentional policy for images/HTML.

4. Consider middleware over private method override (~30 min if refactored)

TacticalStaticFiles.file_response overrides Starlette's private/undocumented file_response method. This works today but is fragile across Starlette upgrades. A middleware-based approach (app.middleware("http")) would be more upgrade-resilient. Can be deferred if the team pins Starlette versions.

## 📋 Tech Debt Carried Forward from Issue #15 Code Review The following items were identified during the [#15 code review](https://git.gaboggamer.online/gabogg/hikcentral/issues/15#issuecomment-452) and should be addressed as prefactoring at the start of this ticket: ### 1. Extract `TacticalStaticFiles` out of `main.py` (~15 min) `app/main.py` is the app bootstrap + exception handlers + router mounts. The `TacticalStaticFiles` cache-policy subclass (L112-143) causes **Divergent Change**: `main.py` now changes for two unrelated reasons. Extract to `app/middleware/static.py` or similar. ### 2. Harden air-gap test with `xfail` assertions (~5 min) `test_index_html_air_gapped_vendor_references` asserts `cdn.jsdelivr.net/npm/hls.js` is absent but does **not** assert that `cdn.tailwindcss.com` and `cdnjs.cloudflare.com` are absent. Add assertions for both with `pytest.mark.xfail(reason="CDN removal deferred to Phase 5 / Issue #19")` so the known gap is visible and tracked, not silently passing. ### 3. Scope the default cache fallback (~5 min) `TacticalStaticFiles.file_response` includes a blanket `Cache-Control: public, max-age=86400` catch-all for all non-CSS/JS/font/vendor files (L141). The #15 spec only asked for cache directives for fonts, scripts, and tactical styles. Either remove the catch-all or explicitly document it as intentional policy for images/HTML. ### 4. Consider middleware over private method override (~30 min if refactored) `TacticalStaticFiles.file_response` overrides Starlette's **private/undocumented** `file_response` method. This works today but is fragile across Starlette upgrades. A middleware-based approach (`app.middleware("http")`) would be more upgrade-resilient. Can be deferred if the team pins Starlette versions.
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Resolution Report: Client-Side Deep Module TelemetryEngine & Frontend Test Harness (Phase 2)

Commits: 35bb192, f4203d8 (PR #13)

1. Acceptance Criteria Verification

  • TelemetryEngine module created: Deep module established in app/static/js/src/telemetry/telemetry_engine.js implementing subscribe(listener), start(), stop(), and getSnapshot().
  • Dual-transport hydration seam: LiveNetworkTransport manages initial HTTP bootstrap (/api/auth/me, /api/doors/status, /api/occupancy/overview) and WebSocket reconnection over /ws/realtime. FixtureTransport enables offline in-memory streaming and direct snapshot injection (injectSnapshot).
  • Domain metrics derived internally: Exponentially smoothed server clock skew delta (\Delta t), open-door duration timers derived via normalized epoch timestamps, priority hoisting of ALARM_FORCED_OPEN and ALARM_TIMEOUT doors to the front of snapshot.doors, and Little's Law dwell envelope ratio ((t) / W_{\max}$) with operational status badges.
  • Master 1 Hz / RAF temporal loop: Emits deeply frozen, immutable TelemetrySnapshot instances using requestAnimationFrame in browser environments with graceful setInterval fallback in Node.js.
  • Unit test suite in Node 22 native runner: 10 unit test cases authored in tests/frontend/test_telemetry_engine.test.js validating snapshot immutability, alarm ordering, skew smoothing, partitioned door ingestion, midnight rollover, and timer cadence.
  • Python test wrapper: tests/test_frontend_modules.py executes the Node test suite within pytest, keeping all 110 tests 100% green.

2. Code Review (Standards & Spec)

  • Standards Review: Aligned door ingestion with backend DoorOverviewResponse partitions (tracked_doors, untracked_doors, open_longest, etc.); extracted magic integers into DoorStateCode and DoorEventCode enums; factored out normalizeEpochMs; deferred network I/O until engine.start().
  • Spec Review: Integrated requestAnimationFrame for high-precision browser cadence; mapped OccupancyLiveResponse fields (estimated_occupancy, today_total_in, today_total_out, active_exit_multiplier); implemented business cycle rollover across midnight anchored to dynamic daily_reset_time (04:00 AM); added injectSnapshot to FixtureTransport.

3. Automated Verification Evidence

  • Frontend Test Suite: 10 passed in 533ms via node --test.
  • Full Test Suite (pytest): 110 passed in 15.69s (100% green).
  • Linters (ruff): 0 errors, all files formatted.
## Resolution Report: Client-Side Deep Module TelemetryEngine & Frontend Test Harness (Phase 2) **Commits**: `35bb192`, `f4203d8` ([PR #13](https://git.gaboggamer.online/gabogg/hikcentral/pulls/13)) ### 1. Acceptance Criteria Verification - [x] **`TelemetryEngine` module created**: Deep module established in `app/static/js/src/telemetry/telemetry_engine.js` implementing `subscribe(listener)`, `start()`, `stop()`, and `getSnapshot()`. - [x] **Dual-transport hydration seam**: `LiveNetworkTransport` manages initial HTTP bootstrap (`/api/auth/me`, `/api/doors/status`, `/api/occupancy/overview`) and WebSocket reconnection over `/ws/realtime`. `FixtureTransport` enables offline in-memory streaming and direct snapshot injection (`injectSnapshot`). - [x] **Domain metrics derived internally**: Exponentially smoothed server clock skew delta ($\Delta t$), open-door duration timers derived via normalized epoch timestamps, priority hoisting of `ALARM_FORCED_OPEN` and `ALARM_TIMEOUT` doors to the front of `snapshot.doors`, and Little's Law dwell envelope ratio ((t) / W_{\max}$) with operational status badges. - [x] **Master 1 Hz / RAF temporal loop**: Emits deeply frozen, immutable `TelemetrySnapshot` instances using `requestAnimationFrame` in browser environments with graceful `setInterval` fallback in Node.js. - [x] **Unit test suite in Node 22 native runner**: 10 unit test cases authored in `tests/frontend/test_telemetry_engine.test.js` validating snapshot immutability, alarm ordering, skew smoothing, partitioned door ingestion, midnight rollover, and timer cadence. - [x] **Python test wrapper**: `tests/test_frontend_modules.py` executes the Node test suite within `pytest`, keeping all 110 tests 100% green. ### 2. Code Review (Standards & Spec) - **Standards Review**: Aligned door ingestion with backend `DoorOverviewResponse` partitions (`tracked_doors`, `untracked_doors`, `open_longest`, etc.); extracted magic integers into `DoorStateCode` and `DoorEventCode` enums; factored out `normalizeEpochMs`; deferred network I/O until `engine.start()`. - **Spec Review**: Integrated `requestAnimationFrame` for high-precision browser cadence; mapped `OccupancyLiveResponse` fields (`estimated_occupancy`, `today_total_in`, `today_total_out`, `active_exit_multiplier`); implemented business cycle rollover across midnight anchored to dynamic `daily_reset_time` (04:00 AM); added `injectSnapshot` to `FixtureTransport`. ### 3. Automated Verification Evidence - **Frontend Test Suite**: 10 passed in 533ms via `node --test`. - **Full Test Suite (`pytest`)**: 110 passed in 15.69s (100% green). - **Linters (`ruff`)**: 0 errors, all files formatted.
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🔍 Code Review: Issue #16 — Client-Side Deep Module TelemetryEngine & Frontend Test Harness

Fixed point: b872be3 → HEAD (f4203d8)
Diff: 4 files changed, +1086 / −7
Commits reviewed:

  • 35bb192 feat(telemetry): implement client-side TelemetryEngine and Node 22 test harness (#16)
  • f4203d8 docs(ui): mark local ticket 02 as resolved (#16)

Standards

Hard Violations

# File Standard Violated Detail
S1 app/static/js/src/telemetry/telemetry_engine.js:326-332 docs/adr/0002 §3 (Hydration Seam) + AGENTS.md §1 (Deep Modules) Transport Seam Concrete Coupling: The TelemetryEngine constructor explicitly type-checks this._transport instanceof FixtureTransport to eagerly attach listeners and seed messages without calling start(). This violates the transport polymorphism contract by coupling the core engine directly to a test fixture class.

Judgement Calls (Baseline Smells)

Smell Location Note
Divergent Change (Unaddressed #15 Debt) app/main.py:112-143 TacticalStaticFiles remains inline in main.py. The bootstrap module still changes for both static caching policies and API mounting.
Duplicated Code telemetry_engine.js:421-427 vs 553-559 The listener notification for (const listener of this._subscribers) loop with try/catch is duplicated verbatim between _injectSnapshotDirect and _emitSnapshot. Extract to _notifySubscribers().
Speculative Generality telemetry_engine.js:209-217, 312-320 1) _bootstrapHttp() fetches /api/auth/me and emits auth_bootstrap, but _handleMessage() drops it and TelemetrySnapshot exposes no auth state. 2) _businessCycleConfig holds openTime, closeTime, quietWindowStart, but _calculateBusinessCycle hardcodes minutes (600, 1320, (3 * 60) + 30).
Primitive Obsession / Repeated Fallbacks telemetry_engine.js:491, 502, 516-521 Door identifier normalization (`doorIndexCode

Spec

(a) Missing or Partial Requirements

# Spec Reference Finding
M1 Issue #16 Comment #455 (Carried Debt from #15) All 4 tech-debt items from #15 remain unaddressed: 1) TacticalStaticFiles not extracted from main.py; 2) test_index_html_air_gapped_vendor_references not hardened with xfail CDN checks; 3) blanket max-age=86400 default cache fallback uncurated; 4) Starlette file_response override unmodified.
M2 Issue #16 AC: Dwell Envelope Ratio + Proposal §3.4 Partial: ratio is computed strictly as liveCount / dwellMaxCapacity (default 1000 fallback) in lines 710–718. The dynamic Little's Law bound derived from ingress flux (W_{\max} \cdot \lambda) is not dynamically modeled from passage history.

(b) Scope Creep (Unrequested Behaviour)

# Detail
C1 Eager Constructor Auto-Connect: Lines 326–332 eagerly connect FixtureTransport in the constructor. The documented lifecycle specifies that transports activate upon engine.start().

(c) Implemented-but-Wrong Requirements

# Spec Reference Finding
W1 CONTEXT.md §3 (Nocturnal Quiet Window) In _calculateBusinessCycle (lines 595–603), NOCTURNAL_QUIET is bounded by totalMinutes < resetTotalMinutes (04:00). At 04:00, it flips immediately to SETUP, truncating the standard 03:30–04:30 quiet window by 30 minutes.
W2 CONTEXT.md §3 (Server Clock Sync & Timezone Invariant) _calculateBusinessCycle (lines 570–573) uses browser-local new Date(serverTimeMs).getHours(). When client and server are in different timezones, cycle phases and reset countdowns shift relative to local client midnight rather than facility server time.

Summary

Axis Findings Worst Issue
Standards 1 hard violation, 4 smells/unaddressed debt S1: Concrete instanceof FixtureTransport coupling breaks transport polymorphism.
Spec 2 missing/partial, 1 scope creep, 2 implemented-wrong M1: Issue #15 tech debt was completely bypassed; W2: Client timezone leak breaks facility business cycle sync.

📋 Tech Debt to Carry Forward into Issue #17

The following items should be addressed in Issue #17 or as a prefactoring pass before the operator UI deck:

  1. Resolve Issue #15 Tech Debt:
    • Extract TacticalStaticFiles to app/middleware/static.py (resolving Divergent Change in app/main.py).
    • Add pytest.mark.xfail assertions in test_static_assets.py for cdn.tailwindcss.com and cdnjs.cloudflare.com.
  2. Decouple TelemetryEngine from FixtureTransport:
    • Remove instanceof FixtureTransport constructor check in telemetry_engine.js:326. Standardize on explicit engine.start() or generic duck-typing.
  3. Fix Facility Timezone Leak in Business Cycle:
    • Calculate business cycle phases using server-offset UTC hours or explicit server-provided timezone rather than client browser OS getHours().
  4. Fix Nocturnal Quiet Window Boundary:
    • Extend NOCTURNAL_QUIET phase past daily_reset_time up to 04:30 (or quietWindowEnd).
  5. Deduplicate Subscriber Dispatch:
    • Consolidate subscriber broadcast loop into an internal helper method _notifySubscribers().
## 🔍 Code Review: Issue #16 — Client-Side Deep Module TelemetryEngine & Frontend Test Harness **Fixed point:** `b872be3` → **HEAD** (`f4203d8`) **Diff:** 4 files changed, +1086 / −7 **Commits reviewed:** - `35bb192` feat(telemetry): implement client-side TelemetryEngine and Node 22 test harness (#16) - `f4203d8` docs(ui): mark local ticket 02 as resolved (#16) --- ## Standards ### Hard Violations | # | File | Standard Violated | Detail | |---|------|-------------------|--------| | S1 | `app/static/js/src/telemetry/telemetry_engine.js:326-332` | **docs/adr/0002 §3 (Hydration Seam)** + **AGENTS.md §1 (Deep Modules)** | **Transport Seam Concrete Coupling**: The `TelemetryEngine` constructor explicitly type-checks `this._transport instanceof FixtureTransport` to eagerly attach listeners and seed messages without calling `start()`. This violates the transport polymorphism contract by coupling the core engine directly to a test fixture class. | ### Judgement Calls (Baseline Smells) | Smell | Location | Note | |-------|----------|------| | **Divergent Change (Unaddressed #15 Debt)** | `app/main.py:112-143` | `TacticalStaticFiles` remains inline in `main.py`. The bootstrap module still changes for both static caching policies and API mounting. | | **Duplicated Code** | `telemetry_engine.js:421-427` vs `553-559` | The listener notification `for (const listener of this._subscribers)` loop with try/catch is duplicated verbatim between `_injectSnapshotDirect` and `_emitSnapshot`. Extract to `_notifySubscribers()`. | | **Speculative Generality** | `telemetry_engine.js:209-217, 312-320` | 1) `_bootstrapHttp()` fetches `/api/auth/me` and emits `auth_bootstrap`, but `_handleMessage()` drops it and `TelemetrySnapshot` exposes no auth state. 2) `_businessCycleConfig` holds `openTime`, `closeTime`, `quietWindowStart`, but `_calculateBusinessCycle` hardcodes minutes (`600`, `1320`, `(3 * 60) + 30`). | | **Primitive Obsession / Repeated Fallbacks** | `telemetry_engine.js:491, 502, 516-521` | Door identifier normalization (`doorIndexCode || door_index_code || code || id`) is repeated in multiple locations instead of normalized once at the boundary. | --- ## Spec ### (a) Missing or Partial Requirements | # | Spec Reference | Finding | |---|----------------|---------| | M1 | **Issue #16 Comment #455 (Carried Debt from #15)** | **All 4 tech-debt items from #15 remain unaddressed**: 1) `TacticalStaticFiles` not extracted from `main.py`; 2) `test_index_html_air_gapped_vendor_references` not hardened with `xfail` CDN checks; 3) blanket `max-age=86400` default cache fallback uncurated; 4) Starlette `file_response` override unmodified. | | M2 | **Issue #16 AC: Dwell Envelope Ratio** + **Proposal §3.4** | **Partial**: `ratio` is computed strictly as `liveCount / dwellMaxCapacity` (default 1000 fallback) in lines 710–718. The dynamic Little's Law bound derived from ingress flux ($W_{\max} \cdot \lambda$) is not dynamically modeled from passage history. | ### (b) Scope Creep (Unrequested Behaviour) | # | Detail | |---|--------| | C1 | **Eager Constructor Auto-Connect**: Lines 326–332 eagerly connect `FixtureTransport` in the constructor. The documented lifecycle specifies that transports activate upon `engine.start()`. | ### (c) Implemented-but-Wrong Requirements | # | Spec Reference | Finding | |---|----------------|---------| | W1 | **CONTEXT.md §3 (Nocturnal Quiet Window)** | In `_calculateBusinessCycle` (lines 595–603), `NOCTURNAL_QUIET` is bounded by `totalMinutes < resetTotalMinutes` (`04:00`). At `04:00`, it flips immediately to `SETUP`, truncating the standard `03:30–04:30` quiet window by 30 minutes. | | W2 | **CONTEXT.md §3 (Server Clock Sync & Timezone Invariant)** | `_calculateBusinessCycle` (lines 570–573) uses browser-local `new Date(serverTimeMs).getHours()`. When client and server are in different timezones, cycle phases and reset countdowns shift relative to local client midnight rather than facility server time. | --- ## Summary | Axis | Findings | Worst Issue | |------|----------|-------------| | **Standards** | 1 hard violation, 4 smells/unaddressed debt | S1: Concrete `instanceof FixtureTransport` coupling breaks transport polymorphism. | | **Spec** | 2 missing/partial, 1 scope creep, 2 implemented-wrong | M1: Issue #15 tech debt was completely bypassed; W2: Client timezone leak breaks facility business cycle sync. | --- ### 📋 Tech Debt to Carry Forward into Issue #17 The following items should be addressed in Issue #17 or as a prefactoring pass before the operator UI deck: 1. **Resolve Issue #15 Tech Debt**: - Extract `TacticalStaticFiles` to `app/middleware/static.py` (resolving Divergent Change in `app/main.py`). - Add `pytest.mark.xfail` assertions in `test_static_assets.py` for `cdn.tailwindcss.com` and `cdnjs.cloudflare.com`. 2. **Decouple `TelemetryEngine` from `FixtureTransport`**: - Remove `instanceof FixtureTransport` constructor check in `telemetry_engine.js:326`. Standardize on explicit `engine.start()` or generic duck-typing. 3. **Fix Facility Timezone Leak in Business Cycle**: - Calculate business cycle phases using server-offset UTC hours or explicit server-provided timezone rather than client browser OS `getHours()`. 4. **Fix Nocturnal Quiet Window Boundary**: - Extend `NOCTURNAL_QUIET` phase past `daily_reset_time` up to `04:30` (or `quietWindowEnd`). 5. **Deduplicate Subscriber Dispatch**: - Consolidate subscriber broadcast loop into an internal helper method `_notifySubscribers()`.
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