Surfaces

A surface is the boundary where the corpus meets the outside. Lesson 108 named three: Burn, Inspect, Hatch. The 100 level never opened them. The 200 level organized what lives inside — the bifurcation into main and system corpora, the imprint, the frame, the adaptation of rings across tiers. This lesson opens the surfaces and shows how the outside world reaches what is inside, and how each surface maps to the bifurcation.

Burn

Burn is where frames enter the main corpus.

A source pushes a frame to the Burn surface. Burn reads the frame metadata only — type code, length, entity key. The imprint itself is never touched. Burn does not parse the payload. There can never be a parse failure on the hot path.

If the metadata checks out, the frame is accepted for write. The imprint passes through untouched onto the surface ring.

If the write fails — disk full, ring error, any fault after acceptance — the frame is not lost. It is placed in the tier's remediate folder for later examination and processing. The witness is never discarded because of an infrastructure failure. It is held aside until the problem is resolved.

Burn faces outward. It is the gate through which perception arrives. It validates metadata, never content. It never drops an accepted frame.

Inspect

Inspect is where the main corpus is read.

A consumer queries through Inspect. Give me the last frame. Give me all frames in this time range. Give me all frames for this entity. Give me the frame count. Inspect reads the main corpus — across the surface ring, across the tiers, across the full range that adaptation configured — and returns what was asked for.

Inspect never alters the main corpus. It does not move frames. It does not mark frames as read. It does not consume. It serves. The same frame can be read through Inspect a thousand times and it is unchanged on the ring.

Inspect faces outward. It is the window through which the main corpus serves its truth. One responsibility: read and serve.

Hatch

Hatch serves two roles. It is where the system corpus is read, and it is where commands are received.

System corpus access. The system corpus holds observations of the node's own operation — the passive channel from Lesson 201. Hatch is how you read those observations. Query the system corpus for operational state. What is the current write rate? How full is the surface ring? When did the last cascade happen? How many frames were rejected at Burn? The system corpus holds the answers. Hatch serves them.

Commands. Hatch is also where the node receives management instructions. Reconfigure a tier. Flush to disk. Report diagnostics. Shut down cleanly. These are commands that change the node's behavior without changing its truth — the corpora are not altered by a management command. The node adapts its operation in response.

Hatch faces outward but looks inward. It is the control surface — operational visibility and operational control in one place. Two responsibilities: serve the system corpus, and accept commands.

The bifurcation carried through

Lesson 201 established two corpora — main and system. Lesson 205 shows that the surfaces follow. Each corpus has its own read surface. The main corpus is read through Inspect. The system corpus is read through Hatch. They do not share a read path.

This is not arbitrary. The main corpus and the system corpus hold different things, serve different consumers, and answer different questions. A consumer asking "show me the last temperature reading" queries Inspect. An operator asking "how many frames did Burn reject in the last hour" queries Hatch. Different corpora. Different surfaces. Different audiences.

Burn writes to the main corpus only. The system corpus is written to internally — by the node's own passive channel. No external surface writes to the system corpus. The passive channel is not fed from outside. It observes from inside.

The 200 level complete

Five lessons. One arc.

Bifurcation revealed that the node has two corpora — main and system. Imprint examined what both corpora capture — the shape reality leaves on the sensor. Frame showed how to carry it — packed, canonical, dense. Adaptation configured the rings — range, modalities, tiers. Surfaces exposed the interfaces — Burn writes, Inspect reads the main corpus, Hatch reads the system corpus and accepts commands.

The unit of knowledge from the 100 level is now organized. Its internals are structured. Its interfaces are defined. The 300 level — Orchestration — begins from here: now that the surfaces are understood, coordinate what passes between them.