feat: startup snapshot writing card and progress bars

[asuzuki-jumptrading]

• and snapshot writing card on startup snapshot page
• add progress bar for startup snapshot cards
• fix sparkline shifting bug after completing

[greptile-jt]

Prompt To Fix All With AI

This is a comment left during a code review.
Path: src/features/StartupProgress/Firedancer/Snapshot/SnapshotReadingCard.tsx
Line: 37

Comment:
**Missing division-by-zero guard**

If `total` is `0` (e.g., before the backend reports the actual snapshot size), this computes `0 / 0 = NaN` or `n / 0 = Infinity`. That value propagates to the `ProgressBar` where `pct.toFixed(0)` renders `"NaN%"` or `"Infinity%"`, and the Radix `<Progress>` component receives a non-finite value.

This same pattern appears in all four card files:
- `SnapshotDecompressingCard.tsx:48`
- `SnapshotInsertingCard.tsx:30`
- `SnapshotWritingCard.tsx:34`

Consider guarding against a zero denominator:

```suggestion
    completed == null || total == null || total === 0 ? undefined : (completed / total) * 100;
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (1): Last reviewed commit: "feat: startup snapshot progress bars" | Re-trigger Greptile}

[greptile-jt]

_{Reviews (2): Last reviewed commit: "feat: startup snapshot progress bars" | Re-trigger Greptile}

[greptile-jt]

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[greptile-jt]

Prompt To Fix All With AI

This is a comment left during a code review.
Path: src/features/StartupProgress/Firedancer/Snapshot/SnapshotWritingCard.tsx
Line: 43

Comment:
**Redundant "Writing" throughput prefix**

The `prefix="Writing"` renders as "Writing X MB/sec" inside a card already titled "Writing". The other cards either omit the prefix (Reading, Inserting) or use a contextually different label like `"Output"` (Decompressing). Consider removing the prefix or changing it to something more descriptive.

```suggestion
          <SnapshotThroughput throughput={throughputObj} />
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (5): Last reviewed commit: "feat: startup snapshot writing card" | Re-trigger Greptile}

[greptile-jt]

Prompt To Fix All With AI

This is a comment left during a code review.
Path: src/features/StartupProgress/Firedancer/Snapshot/utils.ts
Line: 8

Comment:
**Duplicate null check — `total` is never validated**

`completed != null` is checked twice instead of also checking `total != null`. The second condition should be `total != null`. In practice this doesn't cause a wrong result today because the final `total === completed` implicitly fails when `total` is `null`/`undefined` and `completed` is a number, but the intent is clearly to guard both parameters.

```suggestion
    completed != null && total != null && total === completed;
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (6): Last reviewed commit: "feat: startup snapshot writing card" | Re-trigger Greptile}

[greptile-jt]

Prompt To Fix All With AI

This is a comment left during a code review.
Path: src/features/StartupProgress/Firedancer/Snapshot/index.tsx
Line: 185-188

Comment:
**Progress fraction stuck at 0 when writing data is unavailable**

`phaseCompleteFraction2` evaluates to `0` whenever `writeOutDecompressedBytes` is `null`/`undefined` (e.g., the backend hasn't started reporting writing progress yet, or an older backend version doesn't include the `snapwr` fields). Since the overall fraction is `Math.min(phaseCompleteFraction1, phaseCompleteFraction2)`, this pins the entire `phaseCompleteFraction` to `0` even while inserting is actively progressing.

Concretely, once `totalDecompressedBytes > 0` (decompression has started) but `writeOutDecompressedBytes` is still null/undefined, `phaseCompleteFraction2 = 0`, making the PhaseHeader show 0% regardless of `phaseCompleteFraction1`.

Consider falling back to `phaseCompleteFraction1` when writing data is not yet available:

```suggestion
  const phaseCompleteFraction =
    writeOutDecompressedBytes == null
      ? phaseCompleteFraction1
      : Math.min(phaseCompleteFraction1, phaseCompleteFraction2);
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (7): Last reviewed commit: "feat: startup snapshot writing card" | Re-trigger Greptile}

[greptile-jt]

_{Reviews (8): Last reviewed commit: "feat: startup snapshot writing card" | Re-trigger Greptile}

[greptile-jt]

Prompt To Fix All With AI

This is a comment left during a code review.
Path: src/features/StartupProgress/Firedancer/Snapshot/utils.ts
Line: 12

Comment:
**`progressPct` can exceed 100%**

For the Inserting and Writing cards, `total` is `totalDecompressedBytes` — an estimate derived from the current compression ratio (`totalCompressedBytes * decompressDecompressedBytes / decompressCompressedBytes`). While decompression is still in progress, this estimate can temporarily be lower than the actual total. If `completed` (a real backend value) exceeds the estimate, `progressPct` can go above 100, causing the text to render e.g. "105%".

Consider clamping to 100:

```suggestion
      completed == null || !total ? undefined : Math.min((completed / total) * 100, 100),
```

How can I resolve this? If you propose a fix, please make it concise.

_{Reviews (9): Last reviewed commit: "feat: startup snapshot writing card" | Re-trigger Greptile}

[greptile-jt]

progressPct can exceed 100%

For the Inserting and Writing cards, total is totalDecompressedBytes — an estimate derived from the current compression ratio (totalCompressedBytes * decompressDecompressedBytes / decompressCompressedBytes). While decompression is still in progress, this estimate can temporarily be lower than the actual total. If completed (a real backend value) exceeds the estimate, progressPct can go above 100, causing the text to render e.g. "105%".

Consider clamping to 100:

Suggested change

	completed == null || !total ? undefined : (completed / total) * 100,
	completed == null || !total ? undefined : Math.min((completed / total) * 100, 100),

Prompt To Fix With AI

This is a comment left during a code review.
Path: src/features/StartupProgress/Firedancer/Snapshot/utils.ts
Line: 12

Comment:
**`progressPct` can exceed 100%**

For the Inserting and Writing cards, `total` is `totalDecompressedBytes` — an estimate derived from the current compression ratio (`totalCompressedBytes * decompressDecompressedBytes / decompressCompressedBytes`). While decompression is still in progress, this estimate can temporarily be lower than the actual total. If `completed` (a real backend value) exceeds the estimate, `progressPct` can go above 100, causing the text to render e.g. "105%".

Consider clamping to 100:

```suggestion
      completed == null || !total ? undefined : Math.min((completed / total) * 100, 100),
```

How can I resolve this? If you propose a fix, please make it concise.