Removed dead code and consolidated duplicated logic across the project

[CodyCBakerPhD]

Behaviour-preserving cleanups from the code review, one commit per approved group so each reads on its own:

1. Un-exported symbols only used inside their own file
2. Deleted dead code, stylesheet rules and stray comments
3. Removed state and interface fields nothing reads
4. Simplified unreachable branches and redundant expressions
5. Extracted shared helpers for expressions repeated across src/lib and src/ui
6. Consolidated repeated UI construction and split up the longest renderers
7. Merged duplicate stylesheet rules
8. Shared the fixtures the unit tests were each redeclaring
9. Tidied the demo generator's repeated fragments

No observable behaviour, public API or configuration changes; tests, lint, types and pre-commit pass after every commit. The demo generator was run before and after with stubbed ffmpeg/ffprobe and writes an identical dataset with identical ffmpeg argv. Groups 10 and 11 of the review and its "needs verification" items are left for later, as asked.

Prompts

Original request:

Role: You are a senior software engineer performing a rigorous, functionality-preserving code review of this entire project. Your goal is to identify concrete opportunities to improve code quality, maintainability, and clarity without changing any observable behavior or public API.

Hard Constraints (do not violate)
Do NOT alter functionality. No behavior changes, no bug "fixes" that change outputs, no feature additions.
Do NOT change public/exported APIs, signatures, or contracts that external callers or other modules rely on.
Do NOT modify configuration, environment behavior, or runtime side effects.
Every proposed change must be behavior-neutral and independently verifiable.
If you're uncertain whether something is truly dead or safe to change, flag it as "needs verification" rather than assuming.
Scope of Analysis
Systematically review the whole project for:

Dead / unreachable code
Unused functions, methods, classes, variables, constants, imports, and files
Unreachable branches, redundant conditionals, code after early returns
Commented-out code blocks that should be removed
Feature-flagged or legacy paths that are provably never executed
Duplication & consolidation
Repeated logic that can be extracted into a shared internal helper
Near-identical functions that can be merged or parameterized
Copy-pasted blocks, redundant utility implementations
Internal function/structure cleanup
Overly long functions that can be decomposed (internally, without changing behavior)
Poor naming that reduces readability
Unnecessary indirection or wrapper functions that add no value
Inconsistent patterns for the same operation across the codebase
Minor safe improvements
Redundant type conversions, unnecessary allocations, obvious no-ops
Simplifiable boolean/conditional expressions
Unused dependencies in the manifest/package files
Method (think step by step)
First, map the project structure and identify entry points, public surface, and module boundaries so you can reason about what is reachable and what is internal.
For each candidate issue, trace usages across the whole codebase to confirm it is genuinely dead / duplicated / internal before proposing a change.
Rank findings by confidence (High/Medium/Low that the change is safe) and impact.
Output Format
Produce a structured report:

Summary: high-level overview of code health and top themes.
Findings table/list, each with:
ID & category (dead code / duplication / consolidation / cleanup)
Location (file + line/function)
Description of the issue
Proposed change (concrete, minimal, behavior-neutral)
Confidence it's safe (High/Medium/Low) + reasoning
Verification step (e.g., which tests cover it, or how to confirm no callers)
"Needs Verification" section: items you suspect but cannot prove safe alone.
Recommended order of changes, grouped so each group can be applied and tested independently.
Do not apply any changes yet — deliver the review first for approval. When changes are approved, apply them in small, independently reviewable, behavior-preserving commits.

Follow-ups, in order (the session was also resumed several times with "Continue from where you left off."):

Try again

I hit my usage limit while you were working, but it has reset now. Please continue from where you left off.

Apply groups 1 through 9, skip 10 and 11 for now

🤖 Generated with Claude Code

https://claude.ai/code/session_01EG5Tqc6NC6f9PCzXm7qS6t

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Generated by Claude Code

[github-actions]

PR Preview Action v1.8.1
🚀 View preview at https://brain-bbqs.github.io/encoding-helper/pr-preview/pr-39/
Built to branch gh-pages at 2026-09-03 05:24 UTC. Preview will be ready when the GitHub Pages deployment is complete.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 59.54357% with 195 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/ui/abPanel.ts	37.50%	22 Missing and 3 partials ⚠️
src/ui/compareTab.ts	60.00%	21 Missing and 3 partials ⚠️
src/ui/analysisTab.ts	0.00%	19 Missing ⚠️
src/ui/fileLoading.ts	0.00%	17 Missing ⚠️
src/ui/encodeTab.ts	72.54%	14 Missing ⚠️
src/ui/seekTab.ts	25.00%	12 Missing ⚠️
src/ui/formControls.ts	50.00%	9 Missing and 1 partial ⚠️
src/ui/zoomPan.ts	25.00%	9 Missing ⚠️
src/lib/seekReport.ts	38.46%	8 Missing ⚠️
src/ui/demosPage.ts	45.45%	6 Missing ⚠️
... and 18 more

Files with missing lines	Coverage Δ
src/lib/analysisDoc.ts	96.36% <100.00%> (-0.78%)	⬇️
src/lib/appUrl.ts	90.24% <100.00%> (ø)
src/lib/atomLayout.ts	96.29% <100.00%> (+1.05%)	⬆️
src/lib/bitrateTimeline.ts	96.29% <100.00%> (ø)
src/lib/chunkedSource.ts	61.53% <ø> (ø)
src/lib/cliCommand.ts	96.00% <100.00%> (+2.12%)	⬆️
src/lib/containerKb.ts	100.00% <ø> (ø)
src/lib/demoArchive.ts	92.30% <100.00%> (+1.68%)	⬆️
src/lib/dom.ts	80.15% <100.00%> (+5.37%)	⬆️
src/lib/mediabunny.ts	33.33% <ø> (ø)
... and 33 more

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