give the smelter and the plant a recipe of their own

They had no recipe at all: their buffers were unioned over every recipe of
their type, so one smelter accepted all four ores at once, held three kinds of
ingot at once, and ran whichever recipe happened to have its inputs. That is
four recipes coexisting in one building.

New REQ-BLD-AUTO-RECIPE makes them ordinary selectable-recipe buildings that
size their buffers for the one recipe they hold, with a single addition: while
no recipe is set, the first material offered at an input port that any of their
recipes consumes selects it. That covers every intake path, direct coupling
included -- a building that accepts nothing would otherwise leave a coupled
producer stuck at its port forever. Ports in order, config order as tie-break,
so the choice is deterministic.

Once set the recipe never changes on its own, which is what settles the case of
recipes sharing some inputs but not others: there is no second guess to make.
The player changes it through the ordinary selection dialog, which clears the
buffers and so also frees a building holding part of a cycle nothing feeds any
more -- no separate clear action is needed. The dialog's clearing option reads
(Auto) rather than (None) there, since it returns the building to automatic
selection rather than leaving it idle.

Consequently these buildings can now be grey, have a recipe control in the
selection card, and drop the special cases they needed for having no recipe to
name: the buffer-chip union and the recipe summary's "recipe it ran last".

Requirements only; the implementation follows.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Ne3mejABZoLWKLh8fgpM3x

docs/requirements.md

@@ -145,14 +145,18 @@ Any ship, module, building, or assembler recipe id that appears in no unlock gro
 - REQ-BLD-DECON-QUEUE: Fully-built factory buildings marked for demolition (REQ-BLD-DECONSTRUCT) enter a **deconstruction queue** that is processed one building at a time and runs in parallel with the construction queue (REQ-BLD-QUEUE) — the two queues advance independently and simultaneously. Each building takes `world.toml [world].deconstruction_time_seconds` (default 0.1) to deconstruct, the same duration for every building type. When a building's deconstruction completes it is removed from the world and its refund is credited (REQ-BLD-DECONSTRUCT). A building **stops operating the moment it enters the queue**: it runs no production and transports no items, and no longer participates as a live building (its tunnel pairing is re-evaluated as if it were gone, REQ-BLD-TUNNEL-PAIR), but it still physically occupies its tiles until removed, so those tiles stay blocked for placement. A queued building can be taken back out of the deconstruction queue before it is removed (REQ-BLD-DECONSTRUCT-CLICK, REQ-BLD-DECONSTRUCT-BOX) — including the one currently being deconstructed; doing so discards any deconstruction progress, credits no refund, and the building resumes operating (and re-pairs, REQ-BLD-TUNNEL-PAIR). Construction sites never enter the deconstruction queue (REQ-BLD-DECONSTRUCT). Every building in the deconstruction queue is rendered with the deconstruct tint — the `visuals.toml [overlays].deconstruct_tint` color, the same tint applied to a building hovered in deconstruct mode (REQ-UI-DECONSTRUCT-BORDER) — so queued buildings are visually distinct.
 - REQ-BLD-DECONSTRUCT-CLICK: While in deconstruct mode (REQ-UI-HOTKEYS, REQ-UI-DECONSTRUCT-BUTTON), left-clicking a placed factory building or construction site in the game world marks it for demolition, following the rules of REQ-BLD-DECONSTRUCT: a fully-built building is added to the deconstruction queue (REQ-BLD-DECON-QUEUE), and a construction site is removed instantly with the full refund. Left-clicking a fully-built building that is **already in the deconstruction queue** instead removes it from the queue (un-queues it, REQ-BLD-DECON-QUEUE), with no refund; repeated clicks on the same building therefore alternate between queueing and un-queueing it. Clicking a building that cannot be deconstructed (the HQ or a player defence station, per REQ-BLD-DECONSTRUCT), or clicking empty world space, has no effect. Deconstruct mode stays active after each action so the player can continue without re-entering the mode; it is exited via the Q toggle (REQ-UI-HOTKEYS) or the Deconstruct button (REQ-UI-DECONSTRUCT-BUTTON).
 - REQ-BLD-DECONSTRUCT-BOX: While in deconstruct mode (REQ-UI-HOTKEYS, REQ-UI-DECONSTRUCT-BUTTON), the player can click and drag a selection box in the game world. A selection rectangle is drawn while dragging, using the same box-drag gesture and coverage semantics as the multi-select box (REQ-UI-MULTI-SELECT). On mouse up, following the rules of REQ-BLD-DECONSTRUCT: every construction site covered by the box is removed instantly with the full refund; and among the fully-built deconstructible buildings covered by the box, if **all** of them are already in the deconstruction queue they are all removed from it (un-queued, REQ-BLD-DECON-QUEUE), otherwise every covered building not yet in the queue is added to the deconstruction queue (already-queued ones stay). Buildings that cannot be deconstructed (the HQ and player defence stations, per REQ-BLD-DECONSTRUCT) are excluded from the box demolition; ships and defence stations are never affected.
-- REQ-BLD-SITE-CONFIG: A construction site — a building that has been placed but is still queued or under construction (REQ-BLD-QUEUE) — can be selected and configured exactly like the equivalent operational building, before it finishes building. Whatever configuration the building type supports is available on the site: the recipe for a Miner or Assembler (REQ-UI-SELECT-BUTTON), the produced-ship schematic and its module layout for a Shipyard (REQ-UI-SELECT-BUTTON, REQ-MOD-UI-PREVIEW, REQ-MOD-UI-DIALOG), and the output filters for a Splitter (REQ-BLD-SPLITTER) — all set through the same selection panel controls (REQ-UI-CONFIG-INLINE). Only currently unlocked recipes and schematics are offered, exactly as for operational buildings (REQ-LOCK-UI-RECIPE, REQ-LOCK-UI-SCHEMATIC, REQ-LOCK-UI-SPLITTER). The configuration is stored on the construction site and carries over unchanged when construction completes, so the building becomes operational already configured. A construction site has no input/output buffers and runs no production cycle, so the buffer and production-progress portions of the panel (REQ-UI-SINGLE-SELECTION, REQ-UI-PRODUCTION-PROGRESS) are not shown for it; only its construction progress (REQ-UI-CONSTRUCTION-PROGRESS) and its configuration controls appear. (Blueprint placement already applies a stored recipe or schematic to a construction site on placement per REQ-UI-BLUEPRINT-PLACE; this requirement additionally lets the player set or change that configuration directly on an existing site.)
+- REQ-BLD-SITE-CONFIG: A construction site — a building that has been placed but is still queued or under construction (REQ-BLD-QUEUE) — can be selected and configured exactly like the equivalent operational building, before it finishes building. Whatever configuration the building type supports is available on the site: the recipe for a Miner, Assembler, Smelter or Reprocessing Plant (REQ-UI-SELECT-BUTTON, REQ-BLD-AUTO-RECIPE), the produced-ship schematic and its module layout for a Shipyard (REQ-UI-SELECT-BUTTON, REQ-MOD-UI-PREVIEW, REQ-MOD-UI-DIALOG), and the output filters for a Splitter (REQ-BLD-SPLITTER) — all set through the same selection panel controls (REQ-UI-CONFIG-INLINE). Only currently unlocked recipes and schematics are offered, exactly as for operational buildings (REQ-LOCK-UI-RECIPE, REQ-LOCK-UI-SCHEMATIC, REQ-LOCK-UI-SPLITTER). The configuration is stored on the construction site and carries over unchanged when construction completes, so the building becomes operational already configured. A construction site has no input/output buffers and runs no production cycle, so the buffer and production-progress portions of the panel (REQ-UI-SINGLE-SELECTION, REQ-UI-PRODUCTION-PROGRESS) are not shown for it; only its construction progress (REQ-UI-CONSTRUCTION-PROGRESS) and its configuration controls appear. (Blueprint placement already applies a stored recipe or schematic to a construction site on placement per REQ-UI-BLUEPRINT-PLACE; this requirement additionally lets the player set or change that configuration directly on an existing site.)
 
 ## Building Types
 
 - REQ-BLD-MINER: **Miner** (2×2): The player selects which ore type it extracts. Each ore type corresponds to a `recipes.toml [[recipe]]` entry with `building = "miner"`, defining the output item and `duration_seconds`. Every asteroid tile is equivalent for mining — any miner can produce any ore type based solely on its selected recipe. Ore never depletes. Only implicitly unlocked ore-type recipes are available for selection (REQ-LOCK-UI-RECIPE).
-- REQ-BLD-SMELTER: **Smelter** (2×2): Converts ore or scrap into basic materials. No recipe selection required. Inputs, outputs, and rates are defined in `recipes.toml [[recipe]]` entries with `building = "smelter"`.
+- REQ-BLD-SMELTER: **Smelter** (2×2): Converts ore or scrap into basic materials. Its recipe is selected as any other building's is, except that it also picks one for itself from the first material it is offered (REQ-BLD-AUTO-RECIPE). Inputs, outputs, and rates are defined in `recipes.toml [[recipe]]` entries with `building = "smelter"`.
 - REQ-BLD-ASSEMBLER: **Assembler** (3×3): The player selects a recipe from the config-defined crafting tree. Produces the selected output item at the rate defined in the corresponding `recipes.toml [[recipe]]` entry with `building = "assembler"`. Only implicitly unlocked recipes are available for selection (REQ-LOCK-UI-RECIPE).
-- REQ-BLD-REPROCESSING: **Reprocessing Plant** (3×3): Consumes scrap per cycle and produces exactly one **kind** of higher-level intermediate product per cycle via weighted random pick, in that output's configured amount (which may be more than one item). The input quantity, possible output items, per-output weights, and amounts are defined in `recipes.toml [[recipe]]` entries with `building = "reprocessing_plant"` (`inputs`, `outputs[].item`, `outputs[].amount`, `outputs[].weight`). Weights are normalized at load time; their sum does not need to equal 1. The output is rolled at cycle start (see REQ-MAT-CYCLE); the pool of eligible outputs is restricted to implicitly unlocked item types (REQ-LOCK-REPROCESSING-POOL). Its output side follows the general rules with no exception: one buffer per possible output item (REQ-MAT-OUTPUT-BUFFER), and a cycle starts only when every possible roll would fit (REQ-MAT-CYCLE) — which is also what denies the player a reroll by stalling the output belt.
+- REQ-BLD-REPROCESSING: **Reprocessing Plant** (3×3): Consumes scrap per cycle and produces exactly one **kind** of higher-level intermediate product per cycle via weighted random pick, in that output's configured amount (which may be more than one item). The input quantity, possible output items, per-output weights, and amounts are defined in `recipes.toml [[recipe]]` entries with `building = "reprocessing_plant"` (`inputs`, `outputs[].item`, `outputs[].amount`, `outputs[].weight`). Weights are normalized at load time; their sum does not need to equal 1. The output is rolled at cycle start (see REQ-MAT-CYCLE); the pool of eligible outputs is restricted to implicitly unlocked item types (REQ-LOCK-REPROCESSING-POOL). Its output side follows the general rules with no exception: one buffer per possible output item (REQ-MAT-OUTPUT-BUFFER), and a cycle starts only when every possible roll would fit (REQ-MAT-CYCLE) — which is also what denies the player a reroll by stalling the output belt. Like the Smelter it picks its recipe from the first material it is offered while none is set (REQ-BLD-AUTO-RECIPE).
+- REQ-BLD-AUTO-RECIPE: **Automatic recipe selection.** The Smelter and the Reprocessing Plant (REQ-BLD-SMELTER, REQ-BLD-REPROCESSING) are *auto-recipe buildings*. They carry a selected recipe and are configured exactly as a Miner or Assembler is — the same selection button and dialog (REQ-UI-SELECT-BUTTON), buffers sized for that one recipe alone (REQ-MAT-INPUT-BUFFER, REQ-MAT-OUTPUT-BUFFER), and the same pre-configuration on a construction site (REQ-BLD-SITE-CONFIG). They differ in one respect only:
+  - **Selection while none is set.** When such a building has no recipe, the first material offered at any of its input ports that some recipe of its type consumes selects that recipe; the material is then accepted as normal. This holds for every intake path — a belt, splitter or tunnel exit at an input port, and a directly coupled producer (REQ-MAT-DIRECT-COUPLE) — because a building that accepts nothing would otherwise leave a coupled producer stuck at its port forever. The choice is deterministic: input ports are examined in order, and where several recipes of the type consume the offered material the first in config order wins.
+  - **No further switching.** Once a recipe is set the building keeps it. It does not switch when its buffers run empty, nor when a material belonging to another of its recipes arrives — that material is simply not an accepted input, exactly as for any other building.
+  - **The player is always in control.** Selecting a different recipe clears the buffers (REQ-MAT-INPUT-BUFFER, REQ-MAT-OUTPUT-BUFFER); that is how a building left holding part of a cycle nothing feeds any more is freed, and how a selection the player did not want is corrected. For these buildings the dialog's clearing option is captioned `(Auto)` rather than `(None)` (REQ-UI-SELECT-OPTIONS): it unsets the recipe and hands the building back to automatic selection.
 - REQ-BLD-SHIPYARD: **Shipyard** (4×2): The player selects a schematic. When all required materials — the ship's base materials (`[ship.schematic].materials`) plus the materials of all modules in the configured layout (REQ-MOD-MATERIALS) — are present in its input buffer, the shipyard consumes them and begins a production cycle lasting the ship's base `[ship.schematic].production_time_seconds` plus the sum of production times contributed by all module instances in the configured layout (REQ-MOD-PRODUCTION-TIME). One ship of that type is spawned with the configured modules when the cycle completes. The shipyard cannot start a new cycle while one is in progress. If the player confirms a layout change (REQ-MOD-UI-DIALOG) while a production cycle is in progress, the current cycle is cancelled and all consumed materials are discarded; the shipyard returns to idle with the new layout configuration. Confirming a layout identical to the one already configured is not a change and cancels nothing (REQ-MAT-INPUT-BUFFER).
 - REQ-BLD-SALVAGE-BAY: **Salvage Bay** (3×2): A dedicated drop-off point for salvage ships. It has a single output buffer — scrap is the only thing it ever holds — whose holding capacity is defined by the `output_buffer_capacity` field of the `salvage_bay` entry in `buildings.toml` (rather than by a production cycle, since the Salvage Bay has no recipe). A ship at the bay hands over one unit of scrap per tick while the buffer has free space; a full buffer blocks further drop-off until space frees up (consistent with the buffer-full semantics of REQ-MAT-OUTPUT-BUFFER). Held scrap is pushed onto connected output belts.
 - REQ-BLD-BELT: **Belt** (1×1): Transports items. A belt tile has one direction (N, S, E, W) set at placement (modified by rotation). Curved belts are auto-derived: when a belt tile's outgoing direction leads into another belt whose direction is orthogonal, the downstream belt is rendered and behaves as a curve. Belt speed is defined in `world.toml [world].belt_speed_tiles_per_second` (REQ-GW-BELT-SPEED). A belt accepts items only through a non-output edge (REQ-MAT-ACCEPT-DIR).
@@ -390,7 +394,7 @@ Any ship, module, building, or assembler recipe id that appears in no unlock gro
 
 - REQ-LOCK-REPROCESSING-POOL: The pool of possible outputs for a Reprocessing Plant cycle (REQ-BLD-REPROCESSING) is restricted to item types that are currently implicitly unlocked (REQ-LOCK-IMPLICIT). Weights are renormalized over the eligible outputs. If no eligible outputs remain, the Reprocessing Plant cannot start a production cycle.
 
-- REQ-LOCK-UI-RECIPE: Locked miner ore-type recipes and assembler recipes are not shown in their respective recipe-selection dialogs (REQ-UI-SELECT-BUTTON).
+- REQ-LOCK-UI-RECIPE: Locked miner ore-type recipes and assembler recipes are not shown in their respective recipe-selection dialogs (REQ-UI-SELECT-BUTTON). Smelter and Reprocessing Plant recipes are never granted by an unlock group (REQ-LOCK-EXPLICIT restricts `recipes` grants to assembler recipes), so they are available from the start and their dialogs list them all; what gates them in practice is whether the building itself is unlocked (REQ-LOCK-BUILDING).
 
 - REQ-LOCK-UI-SCHEMATIC: Locked ship schematics are not shown in the shipyard's schematic-selection dialog (REQ-UI-SELECT-BUTTON).
 
@@ -494,7 +498,7 @@ The screen is a single column: a header bar across the top and the game world vi
 - REQ-UI-PORT-TARGET-GLYPH: While in builder mode (REQ-BLD-BUILDER-MODE), the builder-mode ghost additionally shows, for each of the building's output ports, a directional glyph drawn centered in the port's **target cell** — the cell immediately outside the footprint that the port pushes into, i.e. the cell the surface-mask output-port indicator occupies (see Surface Mask Format). As in REQ-UI-PORT-GLYPH the glyph is a `>` rotated to face the port's exit direction (`>` East, `^` North, `<` West, `v` South), previewing where the port's output will go before placement. This is in addition to the on-tile port glyph of REQ-UI-PORT-GLYPH, and — unlike that indicator — is shown only for the builder-mode ghost, not for operational buildings, construction sites, or the blueprint-placement ghost (REQ-UI-BLUEPRINT-PLACE). A building with multiple output ports (e.g. a splitter) shows one target-cell glyph per port. The target-cell glyph is drawn larger than the on-tile port glyph so it stands out as the flow-direction preview. Exceptions: the Tunnel Entry shows no target-cell glyph, because it receives items (which may arrive from any of its non-mouth edges, REQ-BLD-TUNNEL-ENTRY) rather than emitting into a single adjacent cell; the Shipyard shows none either, because its output port is a ship-spawn point (REQ-SHP-SPAWN-PLAYER) rather than a belt-item output (REQ-MAT-OUTPUT-EMERGE).
 - REQ-UI-STATUS-LIGHT: Every operational production building — Miner, Smelter, Assembler, Reprocessing Plant, Shipyard, and Salvage Bay — renders a small **status light**: a filled circle with a black outline drawn in the building's upper-right corner, letting the player read a building's production state without selecting it. The light is anchored to the footprint corner that is the upper-right corner in the building's default orientation and rotates with the building — like the output-port glyph (REQ-UI-PORT-GLYPH) — so it stays on the same physical corner of the building as it is rotated. The status light is rendered only for operational buildings; construction sites (which instead show construction progress, REQ-UI-CONSTRUCTION-PROGRESS) and the builder-mode ghost do not render it. Buildings that are not production buildings — belts, splitters, tunnel entries/exits, and the HQ — have no status light. The black outline is constant; the fill color reflects the building's current production state.
   - For the five production buildings (Miner, Smelter, Assembler, Reprocessing Plant, Shipyard), the fill color is determined by evaluating, in order:
-    - **Grey** — no recipe or schematic is selected. This applies only to buildings with a player-facing selection (Miner, Assembler, Shipyard); the Smelter and Reprocessing Plant always run an implicit recipe (REQ-BLD-SMELTER, REQ-BLD-REPROCESSING) and are never grey.
+    - **Grey** — no recipe or schematic is selected. Every production building can show it, an auto-recipe building included: it is grey until something is offered at an input port for it to select a recipe from, and again whenever the player hands it back to automatic selection (REQ-BLD-AUTO-RECIPE).
     - **Green** — the building is currently producing: a production cycle is active (REQ-MAT-CYCLE; for the Shipyard, an in-progress production cycle per REQ-BLD-SHIPYARD).
     - **Red** — the building is idle because a required input is missing from its input buffers, so it cannot start a cycle. Missing input takes precedence over a blocked output side: if any required input is missing the light is red even when an output buffer is also out of room.
     - **Yellow** — the building is idle with all required inputs present but the output side cannot take the cycle: at least one item the cycle could produce has no room in its own buffer, so no new cycle can start (REQ-MAT-OUTPUT-BUFFER, REQ-MAT-CYCLE). A buffer short of a full cycle's worth of free space blocks just as a completely full one does.
@@ -558,8 +562,7 @@ The panel shows exactly one **content** at a time, picked from the catalog in RE
 
   | Selection | Header right slot | Configuration group | Runtime group |
   |---|---|---|---|
-  | Miner, Assembler | status | recipe control + recipe summary | buffers + production |
+  | Miner, Assembler, Smelter, Reprocessing Plant | status | recipe control + recipe summary | buffers + production |
-  | Smelter, Reprocessing Plant | status | recipe summary | buffers + production |
   | Shipyard | status | schematic control + layout preview + Configure | buffers + production |
   | Salvage Bay | status | — | buffers |
   | HQ | — | — | block stock + HP |
@@ -582,26 +585,24 @@ The panel shows exactly one **content** at a time, picked from the catalog in RE
   - an **input** chip shows the per-cycle amount below the count (the items consumed per run, e.g. `/ 2 per cycle`), or the count alone when the building has no selected recipe or schematic to give one;
   - an **output** chip shows the count against **that item's own** output buffer capacity as `a / b` (REQ-MAT-OUTPUT-BUFFER), with the item's name below. Each output chip therefore stands for one buffer, and a Reprocessing Plant shows one per possible roll.
 
-  Input and output chips form separately captioned sections (REQ-UI-SELECTION-CARD). A section lists a chip for **every item the building's cycle involves**, and for an auto-recipe building every item it handles at all, whether or not the buffer currently holds any: an empty buffer reads `0` rather than its chip disappearing, so the card keeps one shape while the building runs. A section left with no chips at all is not shown. The production section (REQ-UI-PRODUCTION-PROGRESS) sits **between them**, so the card reads in the direction the materials flow: what goes in, what is being made of it, what has come out. For a selected construction site the buffer sections are omitted (REQ-BLD-SITE-CONFIG).
+  Input and output chips form separately captioned sections (REQ-UI-SELECTION-CARD). A section lists a chip for **every item the building's cycle involves**, whether or not the buffer currently holds any: an empty buffer reads `0` rather than its chip disappearing, so the card keeps one shape while the building runs. A section left with no chips at all is not shown. The production section (REQ-UI-PRODUCTION-PROGRESS) sits **between them**, so the card reads in the direction the materials flow: what goes in, what is being made of it, what has come out. For a selected construction site the buffer sections are omitted (REQ-BLD-SITE-CONFIG).
 
-  **Only unlocked items are listed.** A building's buffers may carry entries for items the player cannot make yet — an auto-recipe building's buffers are sized over *every* recipe of its type (REQ-BLD-SMELTER, REQ-BLD-REPROCESSING), including recipes that are still locked. Those entries are left out of both sections, consistent with the rest of the UI hiding what is not unlocked yet (REQ-LOCK-UI-RECIPE, REQ-LOCK-UI-SPLITTER), so a Smelter shows the ores it can actually smelt rather than every ore in the game.
+  **Only unlocked items are listed.** Should a building's buffers carry an entry for an item the player cannot make yet, it is left out of both sections, consistent with the rest of the UI hiding what is not unlocked yet (REQ-LOCK-UI-RECIPE, REQ-LOCK-UI-SPLITTER).
-
+- REQ-UI-RECIPE-SUMMARY: Below the recipe/schematic selection control, a building running a recipe or schematic shows a one-line **recipe summary**: each input item's icon on its colored square (REQ-UI-ITEM-ICON) with its per-cycle amount and the inputs separated by `+`, an arrow, each output item's icon on its colored square with its per-cycle amount, and the cycle time in seconds. It restates what the building will do without opening the selection dialog, and it is the panel's only display of the cycle time. For a Shipyard the summary is built from the schematic's materials and production time including the placed modules' contributions (REQ-BLD-SHIPYARD, REQ-MOD-STAT-CALC), matching the buffers beneath it. A building with no recipe or schematic selected shows no summary — including an auto-recipe building that has yet to select one (REQ-BLD-AUTO-RECIPE), which shows none until it does and keeps it from then on, so the card does not resize in step with the building's status (REQ-UI-SELECTION-STATUS, REQ-UI-SELECTION-PANEL).
-  **An idle auto-recipe building still shows what it handles.** Having no selected recipe (REQ-BLD-SMELTER, REQ-BLD-REPROCESSING), it would otherwise show empty sections whenever it happens to be between cycles. Its input and output sections instead list the unlocked items of every recipe of its type — the same union its buffers were sized over — with a count and no per-cycle denominator, since no one recipe is in force. While a cycle is running, that cycle's recipe supplies the denominators as for any other building.
-- REQ-UI-RECIPE-SUMMARY: Below the recipe/schematic selection control, a building running a recipe or schematic shows a one-line **recipe summary**: each input item's icon on its colored square (REQ-UI-ITEM-ICON) with its per-cycle amount and the inputs separated by `+`, an arrow, each output item's icon on its colored square with its per-cycle amount, and the cycle time in seconds. It restates what the building will do without opening the selection dialog, and it is the panel's only display of the cycle time. For a Shipyard the summary is built from the schematic's materials and production time including the placed modules' contributions (REQ-BLD-SHIPYARD, REQ-MOD-STAT-CALC), matching the buffers beneath it. Auto-recipe buildings (Smelter, Reprocessing Plant — REQ-BLD-SMELTER, REQ-BLD-REPROCESSING) have no player-selected recipe and so show no selection control; they show the summary of the recipe currently in production and, while between cycles, of the one they ran last. They keep it rather than dropping it, because a summary that came and went with each cycle would resize the card in step with the building's status (REQ-UI-SELECTION-STATUS), which is the one thing the panel must not do while the player is reading it (REQ-UI-SELECTION-PANEL). Such a building shows no summary only until it has run its first cycle. A building with no recipe or schematic selected shows no summary.
 - REQ-UI-PRODUCTION-PROGRESS: For buildings that produce items or ships (miner, smelter, assembler, reprocessing plant, shipyard), the panel's runtime group shows a captioned **production section** between the input and output buffer sections (REQ-UI-SINGLE-SELECTION): a horizontal progress bar filled to the completion of the active production cycle, with that completion beside the caption as an integer percentage (e.g. `72%`), or the text `idle` in place of the percentage and an empty bar when no production cycle is active. The cycle time is shown in the recipe summary (REQ-UI-RECIPE-SUMMARY) rather than repeated here. When no recipe or schematic is selected, the production section is not shown at all.
 - REQ-UI-MULTI-SELECT: The player selects multiple objects by box-drag or by Ctrl+clicking individual objects to add or remove them from the selection. Multi-select operates within a single category (REQ-UI-SELECTION-CATEGORIES). A box-drag that covers at least one building selects buildings (any field objects within the box are ignored — buildings win); a box-drag that covers no building but does cover ships, defence stations, or debris selects all of those field objects together (REQ-UI-ENTITY-CLICK-SELECT, REQ-UI-DEBRIS-MULTI-SELECT).
 - REQ-UI-MULTI-SELECTION: When multiple buildings are selected and the selection does not aggregate (REQ-UI-SELECTION-AGGREGATE), the panel shows a count summary. Its header names the size of the selection as `<n> buildings` in place of an object name, and carries no symbol and nothing in its right slot. Below it is one row per selected building type — the type's symbol, its name, and the number selected as `x<count>` — one type per row, and no per-building detail. A final row shows the **total building block cost** of the selection, captioned `Total cost` with the value followed by the `building_block` item icon (REQ-UI-BLOCKS-ICON, REQ-UI-ITEM-ICON): the sum of each selected building's placement cost (`buildings.toml [[building]].cost`, per REQ-BLD-COST), counting only player-placeable buildings (buildings with a button in the build button bar); non-player-placeable buildings (the HQ and defence stations) are excluded from the total, consistent with the blueprint total (REQ-UI-BLUEPRINT-CARD). Construction sites count at their building type's full placement cost regardless of construction progress.
-- REQ-UI-CONFIG-INLINE: Recipe and schematic configuration for a selected building is shown within this panel, in its configuration group (REQ-UI-SELECTION-CARD). Recipe selection (miner, assembler) and schematic selection (shipyard) use the selection button and dialog (REQ-UI-SELECT-BUTTON) rather than an inline control. For shipyards, the panel additionally shows the ship layout preview and "Configure" button below the schematic selection button (REQ-MOD-UI-PREVIEW).
+- REQ-UI-CONFIG-INLINE: Recipe and schematic configuration for a selected building is shown within this panel, in its configuration group (REQ-UI-SELECTION-CARD). Recipe selection (miner, assembler, smelter, reprocessing plant) and schematic selection (shipyard) use the selection button and dialog (REQ-UI-SELECT-BUTTON) rather than an inline control. For shipyards, the panel additionally shows the ship layout preview and "Configure" button below the schematic selection button (REQ-MOD-UI-PREVIEW).
-- REQ-UI-SELECT-BUTTON: **Recipe and schematic selection control.** Recipe selection (Miner ore type, Assembler recipe) and schematic selection (Shipyard) are each presented in the selection panel as a single **selection button** whose caption is the name of the currently selected recipe or schematic, or a placeholder ("Select recipe" / "Select schematic") when none is selected. Clicking the button opens a modal **selection dialog** that pauses the game (speed set to 0×; on close, the speed is restored to what it was before the dialog was opened) and that opens centered on the selection panel, as every modal opened from the panel does (REQ-UI-PANEL-MODAL). The dialog contains a vertical list of option buttons, one per selectable option, each describing itself (REQ-UI-SELECT-OPTIONS) — only options that are currently unlocked are shown (REQ-LOCK-UI-RECIPE for recipes, REQ-LOCK-UI-SCHEMATIC for schematics). Neither the option buttons nor the selection button carries a tooltip: an option button states what it makes on its own face, and what the building has selected is drawn beneath the selection button as the recipe summary (REQ-UI-RECIPE-SUMMARY), with the production paths of the items involved reachable by hovering the card's item chips (REQ-UI-ITEM-TOOLTIP). Clicking an option button selects that recipe/schematic, closes the dialog, and updates the selection button's caption in the selection panel. The dialog can be dismissed without changing the current selection (e.g. closing it without clicking an option). Selecting a new recipe or schematic has the same effects as before (REQ-MAT-INPUT-BUFFER, REQ-MAT-OUTPUT-BUFFER, REQ-BLD-SHIPYARD).
+- REQ-UI-SELECT-BUTTON: **Recipe and schematic selection control.** Recipe selection (Miner ore type, Assembler recipe, and the Smelter's and Reprocessing Plant's recipe per REQ-BLD-AUTO-RECIPE) and schematic selection (Shipyard) are each presented in the selection panel as a single **selection button** whose caption is the name of the currently selected recipe or schematic, or a placeholder ("Select recipe" / "Select schematic") when none is selected. Clicking the button opens a modal **selection dialog** that pauses the game (speed set to 0×; on close, the speed is restored to what it was before the dialog was opened) and that opens centered on the selection panel, as every modal opened from the panel does (REQ-UI-PANEL-MODAL). The dialog contains a vertical list of option buttons, one per selectable option, each describing itself (REQ-UI-SELECT-OPTIONS) — only options that are currently unlocked are shown (REQ-LOCK-UI-RECIPE for recipes, REQ-LOCK-UI-SCHEMATIC for schematics). Neither the option buttons nor the selection button carries a tooltip: an option button states what it makes on its own face, and what the building has selected is drawn beneath the selection button as the recipe summary (REQ-UI-RECIPE-SUMMARY), with the production paths of the items involved reachable by hovering the card's item chips (REQ-UI-ITEM-TOOLTIP). Clicking an option button selects that recipe/schematic, closes the dialog, and updates the selection button's caption in the selection panel. The dialog can be dismissed without changing the current selection (e.g. closing it without clicking an option). Selecting a new recipe or schematic has the same effects as before (REQ-MAT-INPUT-BUFFER, REQ-MAT-OUTPUT-BUFFER, REQ-BLD-SHIPYARD).
 - REQ-UI-SELECT-OPTIONS: **Option list of the selection dialog.** The selection dialog (REQ-UI-SELECT-BUTTON) lists its options as a **single vertical column** of buttons, one per option, rather than a grid: each button is as wide as the dialog and states what the option does, which needs a line of its own. No option button carries a tooltip — the button face is the whole description, so the player reads every option's inputs, product, and time from the list itself without hovering anything. Should the column be taller than the space the window leaves the dialog — a fully unlocked Assembler offers more options than any window can hold, and a modal is never resized to fit (REQ-UI-PANEL-MODAL) — the list **scrolls** within the dialog rather than the dialog growing past the window.
   - A **recipe** option (Miner, Assembler) shows the **recipe name** on its first line and, beneath it, that recipe drawn as the recipe summary line draws it (REQ-UI-RECIPE-SUMMARY): each input item's icon on its colored square with its per-cycle amount, an arrow, each output item's icon with its amount, and the cycle time. A miner recipe consumes nothing, so its line begins at the arrow.
   - A **ship schematic** option (Shipyard) shows the ship's `display_name` on its first line and, beneath it, the icons and quantities of its base required materials (`[ship.schematic].materials`, excluding any module contributions) with the base production time (`[ship.schematic].production_time_seconds`). A ship is not an item and has no icon of its own, so this line names no output: the button's caption is what it produces.
-  - The `(None)` option shows its text caption alone.
+  - The `(None)` option shows its text caption alone. On an auto-recipe building it is captioned `(Auto)` instead, because there it does not leave the building idle but returns it to automatic selection (REQ-BLD-AUTO-RECIPE).
 - REQ-UI-ITEM-TOOLTIP: **Item production tooltip.** Hovering an item chip in the selection panel — an input or output buffer chip (REQ-UI-SINGLE-SELECTION) or the HQ's block stock chip (REQ-UI-HQ-PANEL) — shows a tooltip telling the player where that item comes from. It has a heading and a body:
   - the heading is the **hovered item's name**. For an input chip this is the only place the item is named at all, since such a chip carries a count and no name (REQ-UI-SINGLE-SELECTION).
   - the body is the caption `Produced by` followed by one **recipe line** per unlocked recipe that produces the item. A recipe line is a small **card** of two rows: the icon of the building that runs the recipe (REQ-UI-BUILD-ICON) and the recipe's name on the first, and the recipe itself on the second, drawn as the recipe summary draws it (REQ-UI-RECIPE-SUMMARY) — each input item's icon on its colored square with its per-cycle amount, the inputs separated by `+`, an arrow, each output item's icon with its amount, and the cycle time. Two rows rather than one because an identity and a cycle read as different things, and a single row of icons, names and numbers runs too long to scan; a card around each because several producers stacked as bare lines read as one field of icons and numbers rather than as separate recipes. A line drawn where its surroundings already frame it — on an option button (REQ-UI-SELECT-OPTIONS), or as the panel's recipe summary — takes no card of its own. An item may have several producers — an iron ingot is smelted from ore, smelted from scrap, and recovered by reprocessing — and the building icon and recipe name are what tell those lines apart and tell the player which building to place for which path.
 
-  **Only recipes the player can run are listed**, consistent with the rest of the UI hiding what the player cannot make yet. What that means differs by building, because only Miner and Assembler recipes are unlocked individually (REQ-LOCK-UI-RECIPE): those are listed once unlocked, while a Smelter's or Reprocessing Plant's implicit recipes (REQ-BLD-SMELTER, REQ-BLD-REPROCESSING) are listed once **their building** is unlocked (REQ-LOCK-BUILDING) — there is no sense in naming a path through a plant the player cannot place. Two cases have no recipe line to show, and each says so in place of the list rather than leaving the tooltip bare:
+  **Only recipes the player can run are listed**, consistent with the rest of the UI hiding what the player cannot make yet. What that means differs by building, because only Miner and Assembler recipes are unlocked individually (REQ-LOCK-UI-RECIPE): those are listed once unlocked, while a Smelter's or Reprocessing Plant's recipes (REQ-BLD-SMELTER, REQ-BLD-REPROCESSING) are listed once **their building** is unlocked (REQ-LOCK-BUILDING) — there is no sense in naming a path through a plant the player cannot place. Two cases have no recipe line to show, and each says so in place of the list rather than leaving the tooltip bare:
   - **An item no recipe produces at all.** Scrap is salvaged from debris (REQ-RES-DEBRIS-DROP) rather than crafted, so its tooltip reads `Salvaged from debris` in place of the `Produced by` caption and lists nothing beneath it.
   - **An item whose every producing recipe is still locked.** The caption stays `Produced by`, and the single line beneath it reads `Undiscovered`: the player is told the item is made somehow, without being shown a path they have not unlocked yet.