fix: strip comments from cached chapter HTML - #3028

Learnt from: Uri-Tauber
Repo: crosspoint-reader/crosspoint-reader PR: 1629
File: src/activities/home/HomeActivity.cpp:119-120
Timestamp: 2026-04-12T12:28:33.205Z
Learning: When reviewing code in this repository (C/C++ sources), set review comment severity according to this policy:
- Use **Major** (🟠) only for defects with realistic risk of crash, out-of-memory (OOM), invalid pointer dereference, data corruption, or other severe issues that are unlikely to be caught in casual/manual device testing.
- Use **Minor** or informational for UX gaps, logic edge-cases, style issues, or missing feature completeness that the author can verify (or has verified) through normal device use.
- Do **not** escalate severity to Major based on behavioral/UX observations alone; assume the author has already tested the feature on their own device and only treat issues as Major if they match the high-risk defect categories above.

Learnt from: jeremydk
Repo: crosspoint-reader/crosspoint-reader PR: 2076
File: src/network/HttpDownloader.cpp:166-171
Timestamp: 2026-05-24T21:10:19.897Z
Learning: Follow the repo’s CLAUDE.md guidance: avoid adding error handling, fallbacks, or extra validation for scenarios that are provably unreachable given existing internal invariants and framework guarantees. Only add validation/guards at true system boundaries (e.g., user input, external APIs/network/IPC). For internal C++ APIs like HttpDownloader, do not add defensive checks against misuse (e.g., an empty std::function callback) when there is no reachable call site that can supply such values—guards in those cases are explicitly discouraged.

Learnt from: Uri-Tauber
Repo: crosspoint-reader/crosspoint-reader PR: 2772
File: lib/Epub/Epub/blocks/TextBlock.cpp:454-458
Timestamp: 2026-07-28T18:42:02.364Z
Learning: When deserializing untrusted data in C++ (e.g., via Serialization.h/serialization::readString), never read an untrusted uint32_t length and pass it directly to std::string::resize. Under -fno-exceptions, allocation failure can abort the process. Implement (and use) a centrally-available fallible, bounded readString API that validates the requested byte length before allocation—preferably by checking it against bytes remaining in the input/file. Migrate all call sites that deserialize strings (e.g., cache readers for metadata such as spine/TOC, image blocks, section anchor maps, and TextBlock ruby <rt> text) to use the new safe API. Do not introduce a fixed maximum “read-only” content cap unless the corresponding writer/parser also enforces the same constraint; otherwise current unbounded ruby <rt> content can cause cache rebuild loops due to mismatch between parse-time and read-time limits.

Learnt from: ngxson
Repo: crosspoint-reader/crosspoint-reader PR: 1218
File: src/activities/ActivityManager.cpp:254-265
Timestamp: 2026-02-27T22:49:59.600Z
Learning: In this codebase, assertions are always enabled (no NDEBUG). Use assert() to crash on programmer errors and surface logic bugs during development and in production builds. Do not rely on asserts for runtime error handling; they should enforce invariants that must always hold. Keep asserts side-effect free and inexpensive, and avoid relying on them for user-visible failures. Include <cassert> where appropriate and document the invariant being tested.

Learnt from: Uri-Tauber
Repo: crosspoint-reader/crosspoint-reader PR: 1245
File: lib/Epub/Epub/Section.cpp:277-308
Timestamp: 2026-03-02T10:14:16.036Z
Learning: Guideline: Strengthen serialization::readString to defend against unbounded growth when reading from disk data. Implement and enforce a maximum allowed length (e.g., a configured or reasonable constant) and validate the incoming length before resizing or allocating. Audit all call sites (e.g., BookMetadataCache, TextBlock, KOReaderCredentialStore, Section cache readers) to ensure they do not rely on unbounded len-based resizing. If the readString API must remain, add internal safeguards (bounds checks, length validation, and error handling) so per-call-site validations are not required. Ensure Section cache files remain versioned (SECTION_FILE_VERSION) and parameter mismatches invalidate caches, but do not rely on unsafe allocations; prefer safe, bounded reads with explicit errors on invalid data.