#+TITLE: Theme-driven nerd-icons colors + theme-studio filetype legend — Spec
#+AUTHOR: Craig Jennings & Claude
#+DATE: 2026-06-23
#+TODO: TODO | DONE SUPERSEDED CANCELLED

* Metadata
| Status   | Ready pending Craig's go — Codex review incorporated 2026-06-23 |
|----------+------------------------------------------------------------|
| Owner    | Craig                                                      |
|----------+------------------------------------------------------------|
| Reviewer | Codex (spec-review)                                        |
|----------+------------------------------------------------------------|
| Related  | [[file:../../todo.org][todo.org: theme-driven nerd-icons colors]]            |
|----------+------------------------------------------------------------|

* Summary

nerd-icons glyphs (completion icons, dirvish, dashboard, ibuffer) are forced to a single color by a runtime tint in =nerd-icons-config.el=, which flattens the per-filetype color information nerd-icons ships and prevents the theme from controlling icon color. This spec drops that tint so icon color becomes theme-driven, and adds a theme-studio representation — a filetype legend over the 34 =nerd-icons-*= color faces — so the assignments are visible and editable where the rest of the theme is built.

* Problem / Context

=nerd-icons-config.el= defines =cj/nerd-icons-tint-color= (default "darkgoldenrod") and =cj/nerd-icons-apply-tint=, which sets the foreground of all 34 =nerd-icons-*= color faces to that one color, applied in the =nerd-icons= =:config= and a =with-eval-after-load= safety net. Every nerd-icons glyph therefore renders darkgoldenrod regardless of type.

Two costs. First, the per-filetype color nerd-icons provides is lost: =nerd-icons-extension-icon-alist= (330 entries) maps each filetype onto one of the 34 shared color faces (e.g. =.el/.sh= → =nerd-icons-purple=, an M-x command → =nerd-icons-blue=, =.zsh= → =nerd-icons-lcyan=), and the tint collapses all of that to one hue. Second, the color is not theme-driven: the tint runs at load and overrides whatever the theme set, so a theme can't own icon color.

theme-studio already inventories the 34 =nerd-icons-*= faces (via the generic package-inventory path), so they are technically editable today — but only as a bare list of face names with no preview of what each color actually hits. There is no representation of the filetype→color mapping, which is the thing that makes coloring these faces meaningful.

* Goals and Non-Goals
** Goals
- Icon color is theme-driven: the 34 =nerd-icons-*= color faces are set by the theme, not by a runtime tint.
- theme-studio shows a filetype legend — a representative set of filetypes rendered with their real icon glyph in the assigned color — that updates live as a face is recolored.
- The =nerd-icons-*= color-face assignments export into the theme and round-trip on import, like every other themed face.
** Non-Goals
- Per-filetype unique colors. nerd-icons shares 34 faces across 330 filetypes; the model is "color the 34 faces", not "assign 330 colors".
- Changing nerd-icons' glyph selection (=icon-for-file= / =icon-for-buffer= logic) or its icon set.
- An exhaustive 330-row legend. The legend is a curated representative sample, not the full alist.
** Scope tiers
- v1: drop the tint; capture native default colors + a curated filetype legend into the inventory; a bespoke nerd-icons preview in theme-studio rendering the legend; export/round-trip; live verification in completion/dirvish/dashboard.
- Out of scope: per-filetype assignment; editing the filetype→face mapping itself (that lives in nerd-icons).
- vNext: extend the legend beyond file extensions to buffer-mode and command/symbol categories if the file set proves insufficient; a "reset to nerd-icons native palette" button.

* Design

** For the user

theme-studio gains a nerd-icons pane. On the left, the 34 =nerd-icons-*= color faces as editable foreground rows (icons are foreground-colored, so foreground is the only relevant attribute). On the right, a filetype legend: a representative list of filetypes — a handful of languages, a directory, a command, a buffer — each drawn as its real icon glyph plus a sample name, in the color of the face that filetype maps to. Recoloring =nerd-icons-purple= immediately repaints every legend row that resolves to purple (=.el=, =.sh=, …), so the assignment's reach is visible at edit time. Export writes the face colors into the theme; with the runtime tint gone, those colors are what render in completing-read, dirvish, dashboard, and ibuffer.

** For the implementer

Three integration points, plus the config removal.

1. Data capture — two artifacts, two owners. Native seed colors are *not* captured here. They already ride theme-studio's existing default-face pipeline (=capture-default-faces.py= → =emacs-default-faces.json= → =apply_default_face_seeds= in =app_inventory.py=), which runs in clean =emacs -Q --batch= and stores each face's untinted =face-default-spec=. All 34 color faces plus =nerd-icons-completion-dir-face= are already present there with native colors (e.g. =nerd-icons-blue= #6A9FB5), so the seed is correct and untinted with no new code. The only *new* capture is the legend metadata: a generated artifact (emitted by =build-inventory.el= or a sibling dump, embedded by =generate.py=) listing the curated legend rows. The schema is in "Legend data contract" below.

2. Bespoke preview. nerd-icons moves from a generic inventory app to a bespoke app (a =BESPOKE_APP_SPECS= / =PREVIEW_KEYS= entry) with a new renderer in =previews.js= that draws the legend rows: for each curated filetype, its glyph + name styled with the effective color of its mapped face, read through the same registry the other previews use. The 34 faces remain editable rows.

3. Export/theme. The package-export path already serializes edited package faces into the theme; nerd-icons rides it. Confirm =build-theme.el= emits =nerd-icons-*= face specs and that WIP round-trips.

4. Config. Remove =cj/nerd-icons-tint-color=, =cj/--nerd-icons-color-faces=, =cj/nerd-icons-apply-tint=, and its two call sites in =nerd-icons-config.el=. The dir-icon advice (=cj/--nerd-icons-color-dir=, which layers =nerd-icons-yellow= onto directory glyphs that otherwise carry no color face) stays — its problem is independent of the tint — but now points at a theme-owned face.

** Legend data contract

The legend artifact is an array of rows, captured once in Emacs (it reads the nerd-icons alists), embedded by =generate.py= like the rest of =APPS=, and rendered by a =previews.js= renderer. Each row is:

- =key= — unique row id (=ext:el=, =dir=, =cmd=, =buf=).
- =label= — the sample name the row shows (=init.el=, =src/=, =M-x command=, =*scratch*=).
- =face= — the owner =nerd-icons-*= color face being themed. The swatch reads its effective color through the same registry the other previews use, so recoloring the face repaints the row live.
- =category= — =extension= | =dir= | =command= | =buffer=, naming the source.
- =glyph= — the nerd-font glyph string, captured for vNext; the v1 swatch renderer does not use it (see the rendering decision).

Source per category: =extension= rows from the =:face= of =nerd-icons-extension-icon-alist= entries; =dir= rows from =nerd-icons-yellow= (the dir-advice face) and =nerd-icons-completion-dir-face=; =command=/symbol rows from the face in =nerd-icons-completion-category-icons=; =buffer= rows from the face resolved through =nerd-icons-mode-icon-alist=. v1 includes the curated extension rows plus one representative row each for dir, command, and buffer — the categories that actually surface in completing-read. A row whose face is unset (e.g. =nerd-icons-completion-dir-face=) falls back to the dir-advice face for its swatch.

* Alternatives Considered

** A — Keep the tint, make it themeable (theme sets cj/nerd-icons-tint-color)
- Good, because it is the smallest change and preserves the single-knob simplicity.
- Bad, because it keeps one color for all icons, which is the exact thing this feature exists to undo — there is no per-filetype representation to build.
- Neutral, because it would still move color into the theme, just at the wrong granularity.

** B — Per-filetype color assignment (one row per extension)
- Good, because it is maximally granular.
- Bad, because 330 rows is unusable, and nerd-icons shares faces, so most rows would be redundant edits of the same underlying face.
- Neutral, because it matches no real user intent — nobody colors 330 extensions by hand.

** C (chosen) — Theme the 34 shared faces + a filetype legend
- Good, because it matches nerd-icons' actual color model, keeps the editable surface small (34), and the legend gives the "what does this color hit" representation Craig asked for.
- Neutral, because the legend is a curated subset of the 330 filetypes, so a rarely-used extension may not appear in the preview (though its color still themes via its shared face).

** D — Enhance the generic preview instead of a bespoke one
- Good, because it is less code.
- Bad, because the generic preview renders face-name rows; it cannot draw icon glyphs grouped by filetype, which is the whole representation.

* Decisions [6/6]

** DONE Color model: theme the 34 shared faces, not per-filetype
- Context: 330 filetypes map onto 34 shared color faces; the data fixes the granularity.
- Decision: We will expose the 34 =nerd-icons-*= color faces as the editable surface and use the filetype list only as a read-only legend.
- Consequences: easier — small editable surface, matches nerd-icons. Harder — a user wanting one filetype a different color from its face-mates can't, without nerd-icons changes (out of scope).

** DONE Legend scope: curated representative filetypes in v1
- Context: 330 entries is too noisy to preview; a representative set communicates the mapping. The row schema is in "Legend data contract".
- Decision: We will hand-curate a representative legend (common languages, a dir, a command, a buffer) covering the faces that actually appear in Craig's completion/dirvish use, and mark the set as the v1 legend.
- Consequences: easier — a clean, readable preview. Harder — the curated set needs occasional maintenance as nerd-icons' alist shifts; an uncovered face has no legend row (still themeable).

** DONE Seed colors: native colors ride the existing default-face pipeline
- Context: theme-studio needs nerd-icons' native palette, not the runtime tint, to seed from.
- Decision: We rely on theme-studio's existing default-face capture (=capture-default-faces.py= → =emacs-default-faces.json= → =apply_default_face_seeds=), which already runs in clean =emacs -Q --batch= and stores each face's untinted =face-default-spec=. No new color capture in =build-inventory.el=.
- Consequences: easier — zero new color-capture code, and the seed is already untinted. Harder — none. Supersedes the original draft's "build-inventory.el emits native defaults" (finding 3), which would have double-seeded. Verified: all 34 color faces + =nerd-icons-completion-dir-face= already present with native colors (=nerd-icons-blue= #6A9FB5).

** DONE Config sequencing: assign theme colors in the change that drops the tint
- Context: dropping the tint before the theme assigns the 34 faces makes completion icons jump from uniform darkgoldenrod to nerd-icons' native multicolor palette until the theme overrides them.
- Decision: We land the theme's explicit nerd-icons color assignments (Phase 4) in or before the change that removes the tint (Phase 3), so there is no uncolored interim. (Proposed by the author; reopen if you'd rather drop the tint standalone and accept the native-palette interim.)
- Consequences: easier — no ugly interim, one coherent switch. Harder — couples the config change to a theme edit rather than landing independently.

** DONE Dir advice + nerd-icons-completion-dir-face
- Context: directory glyphs carry no intrinsic color face; =cj/--nerd-icons-color-dir= layers =nerd-icons-yellow= so a =default= face-remap doesn't catch them. =nerd-icons-completion-dir-face= is unset.
- Decision: We keep the dir advice (its problem is independent of the tint), now pointing at the theme-owned =nerd-icons-yellow=. =nerd-icons-completion-dir-face= is in scope — it is already inventoried and seeded, so it is a themeable row and the legend's dir row's owner face (falling back to =nerd-icons-yellow= while unset).
- Consequences: easier — dir icons stay colored and become themeable. Harder — one more face in the legend (the dir row).

** DONE Legend rendering: color swatch + filetype label in v1, not the nerd-font glyph
- Context: the icons are private-use nerd-font glyphs; rendering them in the browser needs the Symbols Nerd Font loaded into =theme-studio.html=, an added dependency the page does not carry today.
- Decision: v1 legend rows render a color swatch + the sample filetype label + the owner face name, colored by the face's effective color. The captured =glyph= rides along unused; rendering the real glyph is vNext, gated on loading the nerd font into the page.
- Consequences: easier — no browser-font dependency, and swatch + label already answers "which filetype gets which color". Harder — the preview is not a pixel mirror of completing-read (no glyph shape); acceptable, since color, not shape, is what is being themed.

* Review findings [3/3]

** DONE Open decisions block implementation readiness :blocking:
Disposition (accepted): all six decisions are now resolved — the original five plus the legend-rendering decision the schema work surfaced — and the =[6/6]= cookie reads complete. Sequencing (Phase 4 lands with/before Phase 3) and the =nerd-icons-completion-dir-face= scope are both settled; two author-proposed calls (sequencing, glyph rendering) are marked reopen-if-disagree.
The spec still has five =TODO= decisions, including the sequencing of the tint removal relative to theme assignment and whether =nerd-icons-completion-dir-face= is in scope. That blocks readiness because an implementer would have to decide whether Phase 3 can land before Phase 4, and whether the directory completion face is part of the exported/verified surface. Resolve or explicitly risk-accept every decision before implementation starts. (blocking)

** DONE Legend row contract is underspecified :blocking:
Disposition (accepted): added the "Legend data contract" section — row schema (=key= / =label= / =face= / =category= / =glyph=), the per-category source for each row, and the v1 scope call (curated extension rows plus one representative dir / command / buffer row each). The browser data shape and the non-extension sources are now concrete.
The design says the legend includes filetypes plus "a directory, a command, a buffer," but Phase 1 only names =nerd-icons-extension-icon-alist= as the source. In the current code, package preview data is embedded through =APPS= in =scripts/theme-studio/generate.py= and rendered by =scripts/theme-studio/previews.js=, so the implementer needs a concrete browser data shape: the curated row key, display label/sample name, glyph text, owner face, source category, and what source supplies non-extension rows. Define that schema and state whether v1 really includes directory/command/buffer rows or only extension-backed rows. (blocking)

** DONE Native-palette capture path conflicts with the current seed pipeline :blocking:
Disposition (accepted): the finding is right — native colors are already owned by the existing default-face pipeline, which runs in =emacs -Q --batch= and stores untinted =face-default-spec= (verified: 35 nerd-icons faces already in =emacs-default-faces.json= with native colors). Dropped the draft's "build-inventory.el emits native defaults" entirely (it would have double-seeded). The only new capture is the legend metadata; the Seed-colors decision was rewritten to match.
The spec says =build-inventory.el= should emit native defface defaults, but the current Theme Studio default-color path already lives in =scripts/theme-studio/capture-default-faces.py= / =emacs-default-faces.json= and is applied in =scripts/theme-studio/app_inventory.py= via =apply_default_face_seeds=. =build-inventory.el= currently emits only package→face ownership. If the implementation adds native colors in the wrong artifact, nerd-icons could be seeded twice or the package default snapshot could keep carrying the runtime tint. Specify the intended owner: either extend the default-face capture to preserve the untinted =face-default-spec= values for =nerd-icons-*=, or add a separate nerd-icons metadata artifact and define exactly how it overrides =apply_default_face_seeds=. (blocking)

* Implementation phases

** Phase 1 — Legend capture
Emit the curated legend rows (=key= / =label= / =face= / =category= / =glyph=) into a generated artifact and wire it through =generate.py=. Native seed colors are *not* captured here — they already ride the existing default-face pipeline (=capture-default-faces.py= / =emacs-default-faces.json= / =apply_default_face_seeds=), which stores untinted =face-default-spec= values; confirm nerd-icons' faces are present (verified: 35 captured). Tree stays working (data only; no UI change yet).

** Phase 2 — Bespoke nerd-icons preview
Register nerd-icons as a bespoke app with a legend renderer in =previews.js= drawing each curated filetype's glyph + name in its mapped face's effective color, live-updating on recolor. Browser-gated; existing previews unaffected.

** Phase 3 — Drop the runtime tint
Remove the tint defcustom/defconst/function and its two call sites from =nerd-icons-config.el=; keep the dir advice. Live-reload + smoke.

** Phase 4 — Theme assignment + verification
Seed/assign the 34 nerd-icons colors in WIP, confirm export → =WIP-theme.el= and import round-trip, verify live in completing-read / dirvish / dashboard / ibuffer.

* Acceptance criteria
- [ ] theme-studio shows a nerd-icons pane: 34 editable foreground rows + a filetype-legend preview.
- [ ] Recoloring a =nerd-icons-*= face repaints every legend row mapped to it, live.
- [ ] theme-studio opens seeded with nerd-icons' native palette (not darkgoldenrod).
- [ ] Export includes the =nerd-icons-*= face specs; re-import round-trips to the same state.
- [ ] =nerd-icons-config.el= no longer tints; the 34 faces are owned by the theme.
- [ ] In a live frame, completion / dirvish / dashboard icons render the theme's per-filetype colors.
- [ ] run-tests.sh green (Node + browser gates + ERT + Python); =make validate-modules= + launch smoke clean.

* Readiness dimensions
- Data model & ownership: the 34 color faces are user-authored via theme-studio and owned by the theme; the filetype→face legend and native defaults are generated (captured from nerd-icons), read-only. No remote/cache.
- Errors, empty states & failure: a face with no curated legend row simply has no preview row (still editable); a missing nerd-icons (package absent) skips the bespoke app — capture must degrade to the generic path, not error.
- Security & privacy: N/A because no credentials or sensitive data.
- Observability: the legend preview *is* the observability — the user sees exactly which filetypes a color hits before committing.
- Performance & scale: 34 faces + a curated legend (tens of rows); trivial. The capture dump runs once in Emacs, not per render.
- Reuse & lost opportunities: reuses the existing inventory pipeline, the package-export path, and the preview registry from preview-locate; nerd-icons already supplies the extension→face mapping, so we read it rather than re-derive.
- Architecture fit & weak points: integration points are =build-inventory.el= (capture), =app_inventory.py= / =face_data.py= (bespoke registration), =previews.js= (renderer), =generate.py= (embed), =nerd-icons-config.el= (tint removal). Weak point: the curated legend can drift from nerd-icons' alist over versions — mitigated by deriving the mapping from the live alist at capture time, curating only which filetypes to show.
- Config surface: removes =cj/nerd-icons-tint-color= and its machinery; no new public knob (the theme is the surface). =cj/--nerd-icons-color-dir= advice retained.
- Documentation plan: update =nerd-icons-config.el= commentary; a note in theme-studio's =theme-coloring-guide.org= on the nerd-icons pane. No user-facing migration doc needed (personal config).
- Dev tooling: run-tests.sh (theme-studio), =make validate-modules= + launch smoke (config); the capture dump is an =emacsclient -e '(load build-inventory.el)'= step already used.
- Rollout, compatibility & rollback: the change alters the persisted theme (adds nerd-icons face specs) and removes a config knob. Rollback = restore the tint block and drop the nerd-icons specs from the theme. The sequencing decision exists to avoid an uncolored interim.
- External APIs & deps: depends on nerd-icons internals — =nerd-icons-extension-icon-alist= entry shape (=("ext" fn "glyph" :face SYM)=) and the 34 =nerd-icons-*= color faces. Verified live this session (330 entries, sample confirmed; 34 faces in the inventory). The defface-default capture for seeding is the one assumption to verify in Phase 1.

* Risks, Rabbit Holes, and Drawbacks
- Reading defface defaults past a runtime override is the fiddly part — if =face-default-spec= doesn't yield a clean color (some specs are display-conditional), fall back to nerd-icons' source palette values captured once. Timebox the defface-introspection approach before hand-rolling a palette table.
- Org/elisp icon fontification inside theme-studio is HTML, not Emacs faces — the legend renders CSS colors from the captured map, so there is no live Emacs face dependency at preview time (same model as the other previews).

* Review and iteration history
** 2026-06-23 Tue @ 22:17:25 -0400 — Claude — author
- What: initial draft.
- Why: Craig chose to spec the drop-the-tint + theme-studio filetype-legend feature before building (spans config + three theme-studio layers + the theme, with real trade-offs on color model, legend scope, seeding, and sequencing).
- Artifacts: docs/specs/theme-studio-nerd-icons-colors-spec.org; todo.org task (to be created at hand-off).

** 2026-06-23 Tue @ 22:29:01 -0400 — Codex (emacs-d) — reviewer
- *What changed or was recommended:* First review, =Not ready=. Added three blocking findings: unresolved decisions still gate readiness; the legend needs a concrete generated data contract, especially for non-extension rows; and native-palette capture must be assigned to the existing default-face seed pipeline or to a clearly defined metadata override.
- *Why:* The code read confirmed the main direction fits the current implementation: =modules/nerd-icons-config.el= owns the bulk tint and dir advice; Theme Studio package views are generated from =BESPOKE_APP_SPECS= / =APPS= and rendered through =PACKAGE_PREVIEWS=; package export already serializes package face specs. The remaining gaps would still force implementers to invent schema, seed ownership, and sequencing behavior mid-build.
- *Artifacts:* findings [0/3]; code read: =modules/nerd-icons-config.el= (=cj/nerd-icons-apply-tint=, =cj/--nerd-icons-color-dir=), =scripts/theme-studio/build-inventory.el=, =scripts/theme-studio/capture-default-faces.py= / =emacs-default-faces.json=, =scripts/theme-studio/app_inventory.py=, =scripts/theme-studio/face_data.py=, =scripts/theme-studio/generate.py=, =scripts/theme-studio/previews.js=, =scripts/theme-studio/build-theme.el=, =tests/test-nerd-icons-config--apply-tint.el=, =tests/test-nerd-icons-config--color-dir.el=, =todo.org=.

** 2026-06-23 Tue @ 22:37:50 -0400 — Claude — responder
- *What changed:* All three blocking findings accepted and folded in. Added a "Legend data contract" section (row schema + per-category sources + v1 scope). Corrected the data-capture story: native seed colors are owned by the existing default-face pipeline (verified untinted in =emacs-default-faces.json=), so the draft's =build-inventory.el= native-color capture is dropped; only the legend metadata is newly captured. Resolved all five open decisions and added a sixth (legend renders a swatch + label in v1, not the nerd-font glyph). Phase 1 retitled to "Legend capture".
- *Why:* The findings were correct against the code read. The seed-pipeline conflict was the load-bearing one — capturing native colors in =build-inventory.el= would have double-seeded against =apply_default_face_seeds=. Two calls (sequencing, glyph rendering) are author-proposed and marked reopen-if-disagree.
- *Artifacts:* findings [3/3]; decisions [6/6]; code verified this session: =capture-default-faces.py= (reads =face-default-spec= under =-Q=), =emacs-default-faces.json= (35 nerd-icons faces, native colors), =nerd-icons-extension-icon-alist= (330) / =nerd-icons-dir-icon-alist= (27) / =nerd-icons-completion-category-icons= sources.