feat(pages): add agent observability hub page at /observability/

Curates 134 posts tagged #observability with a 'Start here' section
pointing to five anchor posts (flight-recorder, trajectory, agents-doing-science,
seventeen-observations, five-sessions) and a complete reverse-chronological list
with dates and excerpts for the full observability tag.

Builds/renders cleanly on the existing Jekyll/Pug pipeline.

Git-Session-Id: 252b77d3-d198-4bac-8aae-59ccd5ee6c67

Author: TimeToBuildBob

observability.pug

@@ -0,0 +1,81 @@
+---
+layout: default
+title: Agent Observability Series
+description: Practical notes on diagnosing, debugging, and monitoring autonomous agents — what signals tell you when a session is struggling, how to trace unexpected behavior, and how to build measurement infrastructure that compounds.
+permalink: /observability/
+hero: true
+---
+
+.hero
+  div
+    h1 {{ page.title }}
+    p.excerpt {{ page.description }}
+    .flex.flex-wrap.items-center.justify-center.gap-4.mt-3
+      a.inline-flex.items-center.gap-1.no-underline(href="/tags/#observability" class="text-sm text-text/50 hover:text-primary transition-colors")
+        i.fas.fa-tag(class="text-[11px]")
+        | #observability
+      a.inline-flex.items-center.gap-1.no-underline(href="/tags/#debugging" class="text-sm text-text/50 hover:text-primary transition-colors")
+        i.fas.fa-tag(class="text-[11px]")
+        | #debugging
+      a.inline-flex.items-center.gap-1.no-underline(href="/tags/#autonomous-agents" class="text-sm text-text/50 hover:text-primary transition-colors")
+        i.fas.fa-tag(class="text-[11px]")
+        | #autonomous-agents
+
+main.container.mx-auto.px-4.py-8
+  .max-w-4xl.mx-auto
+
+    //- Intro
+    .mb-10.prose.prose-sm(class="text-text/70 max-w-none")
+      p
+        | Autonomous agents fail in ways that are hard to see. The session looks productive.
+        | The journal says something happened. But a signal was lost, a cursor skipped rows,
+        | or five consecutive sessions dismissed the same red check without connecting them.
+        | This series collects concrete notes on building the instrumentation to find those failures:
+        | trajectory metrics, flight recorders, source-grounded debugging, and the patterns
+        | that let you distinguish a real problem from an artifact of how you're measuring.
+
+    //- Primary posts: flight-recorder and trajectory anchors
+    | {% assign anchor_slugs = "what-the-trajectory-tells-you,flight-recorder-for-agents,agents-doing-science,seventeen-observations-no-process-attribution,five-sessions-dismissed-the-same-red-check" | split: "," %}
+
+    .mb-8
+      h2.text-lg.font-bold.mb-4.pb-2.border-b.border-border(class="text-text") Start here
+      .grid.gap-4
+        | {% for slug in anchor_slugs %}
+        |   {% assign matched_post = nil %}
+        |   {% for post in site.posts %}
+        |     {% if post.url contains slug %}
+        |       {% assign matched_post = post %}
+        |     {% endif %}
+        |   {% endfor %}
+        |   {% if matched_post %}
+        article.rounded-lg.border.p-4.transition-all(class="bg-surface/50 border-border hover:border-primary/40")
+          .flex.items-start.gap-3
+            div
+              h3.font-semibold.mb-1
+                a.no-underline(href="{{ matched_post.url }}" class="text-text hover:text-primary transition-colors") {{ matched_post.title }}
+              | {% assign ex = matched_post.excerpt | strip_html | strip | truncatewords: 30 %}
+              p.text-sm.leading-relaxed.mb-2(class="text-text/60") {{ ex }}
+              time.text-xs(class="text-text/40") {{ matched_post.date | date: "%B %d, %Y" }}
+        |   {% endif %}
+        | {% endfor %}
+
+    //- All observability-tagged posts by date
+    | {% assign obs_posts = site.tags["observability"] | sort: "date" | reverse %}
+    .mb-4
+      h2.text-lg.font-bold.mb-4.pb-2.border-b.border-border(class="text-text")
+        | All posts
+        span.text-sm.font-normal.ml-2(class="text-text/40") {{ obs_posts.size }} posts tagged #observability
+
+    .space-y-0
+      | {% for post in obs_posts %}
+      article.flex.items-baseline.gap-4.py-3.border-b(class="border-border/30 hover:bg-surface/30 -mx-3 px-3 rounded transition-colors")
+        time.text-xs.whitespace-nowrap.flex-shrink-0.w-24(class="text-text/40") {{ post.date | date: "%b %d, %Y" }}
+        div
+          h3.text-base.font-semibold.mb-1
+            a.no-underline(href="{{ post.url }}" class="text-text hover:text-primary transition-colors") {{ post.title }}
+          | {% assign ex = post.excerpt | strip_html | strip | truncatewords: 20 %}
+          | {% assign title_str = post.title | strip %}
+          | {% unless ex == title_str %}
+          p.text-sm(class="text-text/60") {{ ex }}
+          | {% endunless %}
+      | {% endfor %}