fix: empty-content guard + finish_reason=length handling + reasoning budget (v0.18.1)

Reasoning models at high effort could spend the entire max_tokens budget
on thinking and return zero visible content with finish_reason=length;
the empty article flowed writer -> editor (reject) -> empty draft post,
with the cost booked as success (2026-06-11 incident: prod run acf24029,
draft post 921; diagnosis: convo pipeline-v2-phase1 seq 12).

- Empty-completion guard at the provider seam (new
  OpenRouter_Completion_Guard): empty/whitespace content is a failure;
  one retry with reasoning disabled (per-call override) when
  finish_reason=length or reasoning was active, then the stage fails.
- finish_reason=length always warning-logged (model, stage, tokens).
- Failed/retried attempts booked to generation_log with
  response_status=error + real token burn; run_decisions verdict rows
  (retry_reasoning_disabled / failed_empty_completion) for v0.18.0 runs.
- Writer-path guard in Content_Generator::execute_stage and
  belt-and-braces empty check in Publisher::create_post.
- Reasoning budget sanity: reasoning.max_tokens cap + completion
  headroom via new prautoblogger_reasoning_max_tokens setting (default
  constant 2048, 0 = legacy uncapped effort mode); cap replaces effort
  when active; governor reservations use the effective ceiling.
- Body assembly moved to Request_Builder::build_body (300-line cap).
- Tests: guard verdict matrix, builder budget shaping, writer/publisher
  guards, full provider retry path.

Agent-Session: prab-empty-draft-guard-20260611

prautoblogger.php

@@ -9,7 +9,7 @@
  * Plugin Name:       PRAutoBlogger
  * Plugin URI:        https://peptiderepo.com/prautoblogger
  * Description:       Monitors social media for trending topics, generates SEO-friendly blog posts using AI, and publishes them on a daily schedule with full cost tracking and self-improvement metrics.
- * Version:           0.18.0
+ * Version:           0.18.1
  * Requires at least: 6.0
  * Requires PHP:      7.4
  * Author:            PeptideRepo
@@ -35,7 +35,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 | Defined here so every file in the plugin can reference paths, versions,
 | and limits without magic strings.
 */
-define( 'PRAUTOBLOGGER_VERSION', '0.18.0' );
+define( 'PRAUTOBLOGGER_VERSION', '0.18.1' );
 define( 'PRAUTOBLOGGER_DB_VERSION', '1.2.0' );
 define( 'PRAUTOBLOGGER_PLUGIN_FILE', __FILE__ );
 define( 'PRAUTOBLOGGER_PLUGIN_DIR', plugin_dir_path( __FILE__ ) );
@@ -49,6 +49,12 @@ define( 'PRAUTOBLOGGER_MAX_RETRIES', 3 );
 // the named get_option() fallbacks — never inline the literals.
 define( 'PRAUTOBLOGGER_DEFAULT_RUN_CEILING_USD', 0.50 );
 define( 'PRAUTOBLOGGER_DEFAULT_REQUEST_JSON_RETENTION_DAYS', 14 );
+// v0.18.1: ceiling on "thinking" tokens per reasoning-enabled LLM call. The
+// request's completion budget (max_tokens) is RAISED by this amount so
+// reasoning can never consume the visible-content budget and return an empty
+// message (the 2026-06-11 empty-draft incident). SETTINGS-backed
+// (prautoblogger_reasoning_max_tokens); 0 disables the cap (pure effort mode).
+define( 'PRAUTOBLOGGER_DEFAULT_REASONING_MAX_TOKENS', 2048 );
 define( 'PRAUTOBLOGGER_RETRY_BASE_DELAY_SECONDS', 2 );
 define( 'PRAUTOBLOGGER_API_TIMEOUT_SECONDS', 180 );
 define( 'PRAUTOBLOGGER_CACHE_TTL_SECONDS', 3600 );