Learnt from: imnotjames
Repo: grimmory-tools/grimmory PR: 195
File: booklore-api/src/main/java/org/booklore/config/logging/RequestLoggingFilterConfig.java:15-19
Timestamp: 2026-03-25T21:02:57.527Z
Learning: In `booklore-api/src/main/java/org/booklore/config/logging/RequestLoggingFilterConfig.java` and `booklore-api/src/main/java/org/booklore/config/logging/filter/RequestLoggingFilter.java`, logging all request headers and payloads at DEBUG level is intentional and accepted behavior in this project. The previous `LoggingFilter` also logged all headers. No header redaction or payload scrubbing is required — the DEBUG log level is considered sufficient access control. The new filter is not profile-gated (unlike the old `Profile("dev")` filter) but relies on `logger.isDebugEnabled()` for gating.

Learnt from: imnotjames
Repo: grimmory-tools/grimmory PR: 449
File: booklore-api/src/main/java/org/booklore/service/book/BookDownloadService.java:139-145
Timestamp: 2026-04-10T08:15:37.436Z
Learning: When using Spring `ContentDisposition.builder(...).filename(name, StandardCharsets.UTF_8).build()` (i.e., explicitly providing UTF-8), the resulting header value should include both the quoted `filename="=?UTF-8?..."` and the RFC 5987 `filename*=` parameters. In this case, any extra ASCII fallback computation (e.g., deriving an ASCII `fallbackFilename` via `NON_ASCII_PATTERN` and calling `.filename(fallbackFilename)`) is likely redundant—prefer calling only `.filename(fallbackName?, StandardCharsets.UTF_8)` as appropriate and let Spring handle the UTF-8 header parameters. Verify by comparing the emitted header for `filename` and `filename*` before deciding to keep an ASCII fallback.

Learnt from: balazs-szucs
Repo: grimmory-tools/grimmory PR: 502
File: booklore-api/src/main/java/org/booklore/service/reader/ChapterCacheService.java:0-0
Timestamp: 2026-04-14T12:43:08.698Z
Learning: For this codebase (booklore-api), target Java 25 with `--enable-preview`, so `_` is intentionally used as an unnamed/ignored variable (e.g., lambda parameter or pattern variable) per Java’s preview feature JEP 456. Do not flag `_` in those contexts as an invalid/reserved identifier; only flag it if it’s used in a non-supported position (e.g., where an unnamed variable is not applicable for the Java preview rules).

Learnt from: imnotjames
Repo: grimmory-tools/grimmory PR: 486
File: booklore-api/src/main/java/org/booklore/service/oidc/OidcGroupMappingService.java:130-159
Timestamp: 2026-04-13T05:02:01.463Z
Learning: In grimmory-tools/grimmory, treat `permissionDemoUser`/`permission_demo_user` as a restricting “limited demo mode” flag: it must never be set to `true` as part of any “grant all permissions” or admin-grant flow. Specifically, in code paths that grant admin permissions (for example the OIDC `isAdmin` branch in `OidcGroupMappingService.applyPermissions`), ensure `permissionDemoUser` is intentionally excluded from the admin-permission block and cannot be turned on; enabling it for admin users is counterproductive.

Learnt from: balazs-szucs
Repo: grimmory-tools/grimmory PR: 502
File: booklore-api/src/main/java/org/booklore/service/reader/ChapterCacheService.java:0-0
Timestamp: 2026-04-14T12:46:56.673Z
Learning: For this project (grimmory-tools/grimmory / booklore-api), prefer modern Java 25 idioms and language/library features when reviewing or suggesting changes. Favor current constructs such as unnamed variables (e.g., `_`) where applicable, records, pattern matching for `switch`/`instanceof`, sealed classes, sequenced collections, `Stream.toList()`, and text blocks. Avoid proposing regressions to older/legacy equivalents unless there’s a concrete compatibility constraint (e.g., a required older runtime/library behavior).