feat: add create-video.sh and four new AI-generated posts

Adds scripts/create-video.sh, which reads a post's prompt.{scene,
environment,style,video} frontmatter and generates its banner video via
Replicate's black-forest-labs/flux-3, extracting the first frame as the
preview PNG. Adds four new posts (the-clockwork-confessor,
the-last-lighthouse, the-ashen-choir, the-serpents-bargain) generated
through this pipeline.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012E2mmywuZyXmPBgSDtNdTL

scripts/create-video.sh

@@ -0,0 +1,233 @@
+#!/bin/sh
+# Generate a post's banner video (01.mp4) and preview image (01.png) via
+# the Replicate black-forest-labs/flux-3 text-to-video model, using the
+# prompt.{scene,environment,style,video} fields already present in the
+# post's frontmatter.
+#
+# Usage:
+#   sh scripts/create-video.sh <path-to-post-dir-or-index.md> [--force] [--dry-run]
+#
+# Requires: REPLICATE_API_TOKEN exported in the environment.
+#
+# Video settings (matching every existing post's square/silent convention,
+# just at higher resolution): 1:1 aspect ratio, 1080p, 5s, no audio.
+
+set -e
+
+print_usage() {
+  echo "Usage: sh scripts/create-video.sh <post-dir-or-index.md> [options]"
+  echo ""
+  echo "Generates a post's banner video (01.mp4) via the Replicate flux-3"
+  echo "text-to-video model, using that post's prompt.{scene,environment,style,video}"
+  echo "frontmatter fields, then extracts the first frame as 01.png."
+  echo ""
+  echo "Arguments:"
+  echo "  <post-dir-or-index.md>   Path to content/posts/<slug>/ or its index.md"
+  echo ""
+  echo "Options:"
+  echo "  -f, --force     Overwrite existing 01.mp4 / 01.png"
+  echo "  --dry-run       Print the constructed prompt and request JSON, make no API call"
+  echo "  -h, --help      Show this help"
+  echo ""
+  echo "Requires REPLICATE_API_TOKEN to be exported in the environment."
+}
+
+FORCE=0
+DRY_RUN=0
+POST_ARG=""
+
+for arg in "$@"; do
+  case "$arg" in
+    -f|--force) FORCE=1 ;;
+    --dry-run) DRY_RUN=1 ;;
+    -h|--help) print_usage; exit 0 ;;
+    -*)
+      echo "Unknown option: $arg" >&2
+      exit 1
+      ;;
+    *) POST_ARG="$arg" ;;
+  esac
+done
+
+if [ -z "$POST_ARG" ]; then
+  print_usage >&2
+  exit 1
+fi
+
+if [ -d "$POST_ARG" ]; then
+  BUNDLE_DIR="${POST_ARG%/}"
+  INDEX_MD="$BUNDLE_DIR/index.md"
+else
+  INDEX_MD="$POST_ARG"
+  BUNDLE_DIR=$(dirname "$POST_ARG")
+fi
+
+if [ ! -f "$INDEX_MD" ]; then
+  echo "Error: $INDEX_MD not found" >&2
+  exit 1
+fi
+
+if [ -z "$REPLICATE_API_TOKEN" ]; then
+  echo "Error: REPLICATE_API_TOKEN is not set in your environment." >&2
+  echo "Export it before running this script, e.g.:" >&2
+  echo "  export REPLICATE_API_TOKEN=r8_..." >&2
+  exit 1
+fi
+
+DEST_MP4="$BUNDLE_DIR/01.mp4"
+DEST_PNG="$BUNDLE_DIR/01.png"
+
+if [ "$FORCE" -ne 1 ]; then
+  if [ -e "$DEST_MP4" ]; then
+    echo "Error: $DEST_MP4 already exists (use --force to overwrite)" >&2
+    exit 1
+  fi
+  if [ -e "$DEST_PNG" ]; then
+    echo "Error: $DEST_PNG already exists (use --force to overwrite)" >&2
+    exit 1
+  fi
+fi
+
+PROMPT_JSON=$(yq --front-matter=extract -o=json '.prompt' "$INDEX_MD")
+
+if [ "$PROMPT_JSON" = "null" ] || [ -z "$PROMPT_JSON" ]; then
+  echo "Error: $INDEX_MD has no prompt.* fields in its frontmatter" >&2
+  exit 1
+fi
+
+SCENE=$(printf '%s' "$PROMPT_JSON" | jq -r '.scene // empty')
+ENVIRONMENT=$(printf '%s' "$PROMPT_JSON" | jq -r '.environment // empty')
+STYLE=$(printf '%s' "$PROMPT_JSON" | jq -r '.style // empty')
+VIDEO=$(printf '%s' "$PROMPT_JSON" | jq -r '.video // empty')
+
+if [ -z "$SCENE" ]; then
+  echo "Error: prompt.scene is missing/empty in $INDEX_MD" >&2
+  exit 1
+fi
+if [ -z "$ENVIRONMENT" ]; then
+  echo "Error: prompt.environment is missing/empty in $INDEX_MD" >&2
+  exit 1
+fi
+if [ -z "$STYLE" ]; then
+  echo "Error: prompt.style is missing/empty in $INDEX_MD" >&2
+  exit 1
+fi
+if [ -z "$VIDEO" ]; then
+  echo "Error: prompt.video is missing/empty in $INDEX_MD" >&2
+  exit 1
+fi
+
+SLUG=$(yq --front-matter=extract '.slug' "$INDEX_MD")
+echo "▶ ${SLUG:-$(basename "$BUNDLE_DIR")}: building prompt from frontmatter"
+
+PROMPT="${SCENE} ${ENVIRONMENT} ${STYLE} ${VIDEO}"
+
+INPUT_JSON=$(jq -n \
+  --arg prompt "$PROMPT" \
+  --arg duration "5" \
+  --arg resolution "1080p" \
+  --arg aspect_ratio "1:1" \
+  '{
+    input: {
+      prompt: $prompt,
+      images: [],
+      duration: $duration,
+      resolution: $resolution,
+      aspect_ratio: $aspect_ratio,
+      generate_audio: false
+    }
+  }')
+
+if [ "$DRY_RUN" -eq 1 ]; then
+  echo "--- Constructed prompt ---"
+  echo "$PROMPT"
+  echo "--- Request body ---"
+  echo "$INPUT_JSON" | jq .
+  echo "(dry run — no API call made)"
+  exit 0
+fi
+
+echo "▶ Submitting generation request to Replicate (flux-3)..."
+CREATE_RESPONSE=$(curl -sS \
+  -X POST \
+  -H "Authorization: Bearer $REPLICATE_API_TOKEN" \
+  -H "Content-Type: application/json" \
+  -H "Prefer: wait=60" \
+  -d "$INPUT_JSON" \
+  https://api.replicate.com/v1/models/black-forest-labs/flux-3/predictions \
+  -w '\n%{http_code}')
+
+HTTP_CODE=$(printf '%s' "$CREATE_RESPONSE" | tail -n1)
+BODY=$(printf '%s' "$CREATE_RESPONSE" | sed '$d')
+
+case "$HTTP_CODE" in
+  2??) : ;;
+  *)
+    echo "Error: Replicate API returned HTTP $HTTP_CODE" >&2
+    echo "$BODY" | jq -r '.detail // .error // .' >&2
+    exit 1
+    ;;
+esac
+
+STATUS=$(printf '%s' "$BODY" | jq -r '.status')
+GET_URL=$(printf '%s' "$BODY" | jq -r '.urls.get')
+PREDICTION_ID=$(printf '%s' "$BODY" | jq -r '.id')
+POLL_BODY="$BODY"
+
+if [ -z "$GET_URL" ] || [ "$GET_URL" = "null" ]; then
+  echo "Error: unexpected response from Replicate (no urls.get):" >&2
+  echo "$BODY" >&2
+  exit 1
+fi
+
+POLL_INTERVAL=5
+MAX_WAIT=600
+ELAPSED=0
+
+while :; do
+  case "$STATUS" in
+    succeeded) break ;;
+    failed|canceled)
+      ERR=$(printf '%s' "$POLL_BODY" | jq -r '.error // "unknown error"')
+      echo "Error: prediction $STATUS: $ERR" >&2
+      exit 1
+      ;;
+  esac
+
+  if [ "$ELAPSED" -ge "$MAX_WAIT" ]; then
+    echo "Error: timed out after ${MAX_WAIT}s waiting on prediction $PREDICTION_ID" >&2
+    echo "Check status manually: curl -H \"Authorization: Bearer \$REPLICATE_API_TOKEN\" $GET_URL" >&2
+    exit 1
+  fi
+
+  sleep "$POLL_INTERVAL"
+  ELAPSED=$((ELAPSED + POLL_INTERVAL))
+
+  POLL_BODY=$(curl -sS -H "Authorization: Bearer $REPLICATE_API_TOKEN" "$GET_URL")
+  STATUS=$(printf '%s' "$POLL_BODY" | jq -r '.status')
+  echo "  … ${ELAPSED}s elapsed, status: $STATUS"
+done
+
+OUTPUT_URL=$(printf '%s' "$POLL_BODY" | jq -r '.output')
+if [ -z "$OUTPUT_URL" ] || [ "$OUTPUT_URL" = "null" ]; then
+  echo "Error: prediction succeeded but no output URL was returned" >&2
+  echo "$POLL_BODY" >&2
+  exit 1
+fi
+
+TMP_DIR=$(mktemp -d "${TMPDIR:-/tmp}/create-video.XXXXXX")
+trap 'rm -rf "$TMP_DIR"' EXIT
+
+TMP_MP4="$TMP_DIR/01.mp4"
+TMP_PNG="$TMP_DIR/01.png"
+
+echo "▶ Downloading generated video..."
+curl -fSL -o "$TMP_MP4" "$OUTPUT_URL"
+
+echo "▶ Extracting first frame as preview PNG..."
+ffmpeg -y -loglevel error -i "$TMP_MP4" -vframes 1 "$TMP_PNG" < /dev/null
+
+mv "$TMP_MP4" "$DEST_MP4"
+mv "$TMP_PNG" "$DEST_PNG"
+
+echo "✓ Wrote $DEST_MP4 and $DEST_PNG"