hybrid-image-search-demo Dev Log #14 — Clock Skew, S3-First Ref Cache, Attribute-Aware Injection

Wed, 15 Apr 2026 00:00:00 +0900

Overview

Short but sharp week. Five commits, all production-hardening: a Google OAuth clock-skew fix blocking logins, ecosystem.config.js made host-portable for PM2 across dev/prod, the reference-image key cache moved off local filesystem onto S3 (so dev and prod see the same state), attribute-aware model auto-injection wired up, and personas relabeled with a 3-shot prompt that adds age estimates.

Previous: hybrid-image-search-demo Dev Log #13

graph TD
 A["Login: Invalid token 'used too early'"] --> B["clock_skew_in_seconds=10"]
 C["ref cache from local fs"] --> D[ref cache from S3]
 E[model auto-injection: any image] --> F[attribute-aware injection by tag]
 G[personas: old labels] --> H[3-shot relabel + age estimates]

Google OAuth clock skew

Context

Login blocked with Invalid Google token: Token used too early, 1776217862 < 1776217863. Check that your computer's clock is set correctly. The server’s clock was ~1 second ahead of Google’s — the JWT iat was in the future from the server’s perspective.

Fix

Added clock_skew_in_seconds=10 to id_token.verify_oauth2_token(...) in backend/src/auth.py:

id_token.verify_oauth2_token(
 token, google_requests.Request(), GOOGLE_CLIENT_ID,
 clock_skew_in_seconds=10,
)

Resolved immediately. A server should never trust its own clock to the second against a third party’s iat — 10 seconds of tolerance is standard practice for JWT validation and doesn’t open any meaningful attack surface.

S3-first reference key cache

Context

The model/reference-image cache was built from the local filesystem. This broke in production because prod’s S3-mounted paths didn’t always reflect the latest uploads, and because dev and prod had divergent local filesystem state. When a user regenerated in “tone only” mode, the UI showed the wrong reference image because the path resolved against local state, not S3 reality.

Fix

ce33906 fix(storage): build ref key cache from S3, not local filesystem — cache construction now enumerates S3 objects directly. All image retrieval paths resolved against S3 keys. Also backfilled existing generation history so old records point to the correct S3 URL.

Attribute-aware model auto-injection

Context

Previous injection logic would pull any image matching a loose condition, so the comparison mode (“tone + angle” vs “tone only”) sometimes injected a model image that didn’t match the tagged attribute. Users saw the wrong reference in the output grid.

Fix

d492ee1 feat(gen): attribute-aware model auto-injection — injection now keys on the tagged attributes (angle, tone) of the requested model folder. Subfolders under s3://diffs-studio-hybrid-search/.../01. Model are treated as attribute groups, one reference per group.

Pre-requisite: each model reference was relabeled so attributes are trustworthy. Grouping by folder means labels are a filesystem-visible schema, not a DB column, which matters because the ops team can audit and edit labels with just S3 browsing.

Persona relabeling with 3-shot prompt + age

Context

Persona labels were set earlier with a zero-shot prompt and did not include age estimates. User-facing filters needed age granularity.

Fix

2743eaf chore(labels): re-label personas with 3-shot prompt and age estimates — re-ran the labeler with three in-context examples per request and an age-range field. Labels pushed to the repo so every server picks them up, avoiding per-instance label drift.

PM2 / TSC fixes

95f8bbc fix(deploy): make ecosystem.config.js host-portable — removed hardcoded absolute paths so the same config works on dev and prod. PM2 now boots the same from any $HOME.
6ebab0d fix(ui): drop unused generatingCount state to unblock tsc build — dead state variable tripped the TypeScript build after a recent cleanup. Deleted and the build passed.

Commit log

Message	Area
fix(deploy): make ecosystem.config.js host-portable	PM2
fix(storage): build ref key cache from S3, not local filesystem	Storage
feat(gen): attribute-aware model auto-injection	Generation logic
fix(ui): drop unused generatingCount state to unblock tsc build	Frontend
chore(labels): re-label personas with 3-shot prompt and age estimates	Labeling

Insights

Two patterns worth locking in. First, “build cache from the source of truth” beats “sync cache with source of truth” every time. The ref-key cache was fragile as long as it started from local state and hoped to reconcile with S3 later; building directly from S3 removes a whole category of drift bugs. Second, the clock-skew fix is a reminder that production OAuth failures are almost always distributed-systems issues (clock sync, DNS propagation, key rotation) rather than crypto issues — a 1-line fix after 10 minutes of log reading, which is exactly how it should feel in a mature stack.

Tsc on ICE-ICE-BEAR-BLOG

hybrid-image-search-demo Dev Log #14 — Clock Skew, S3-First Ref Cache, Attribute-Aware Injection

Overview

Google OAuth clock skew

Context

Fix

S3-first reference key cache

Context

Fix

Attribute-aware model auto-injection

Context

Fix

Persona relabeling with 3-shot prompt + age

Context

Fix

PM2 / TSC fixes

Commit log

Insights