dsh-web-search-exa-dynamic
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An Exa-backed WebSearchProvider for the
DeepSeek Harness ctx.web seam, with Exa
Dynamic Highlights on by default and an /exa command that changes highlights, search type and
result count at runtime.
dsh plugin --profile web add dsh-web-search-exa-dynamic
Why this exists
The first-party @deepseek-ai/dsh-web-search-exa cannot reach Exa Dynamic Highlights, for two
independent reasons:
-
Its request body is hardcoded. It sends contents.highlights.highlightsPerUrl, and no config
field it accepts reaches a dynamic field.
-
Dynamic Highlights is a beta API and needs a header. Every request that sets dynamic: true
must also send Exa-Beta: dynamic-highlights-2026-08-28. That provider's headers are
authorization, content-type, accept and user-agent — no Exa-Beta. Without it Exa answers
HTTP 400:
{"error":"'highlights.dynamic' is in beta. Send the 'Exa-Beta: dynamic-highlights-2026-08-28' request header to use it.","tag":"INVALID_REQUEST"}
This provider sends both, and drops highlightsPerUrl entirely — measured against the live API, Exa
ignores that parameter, returning byte-identical payloads for values 1 and 5. It uses
maxCharacters instead, which is the knob that actually works when Dynamic Highlights are off.
Measured
Real /search calls, one query, 8 results:
| Configuration | Highlight characters |
|---|
| First-party provider's default (no working knob) | 51,152 |
This provider, dynamicHighlights: false + highlightsMaxCharacters: 1500 | 10,973 |
This provider, dynamicHighlights: true (default) | 12,716 |
Dynamic Highlights is not a uniform truncation: it concatenates the retrieved documents into one
input, runs a single forward pass, and allocates a shared budget across the result set — so useful
pages keep more context and redundant ones get less.
Install
dsh plugin --profile web add dsh-web-search-exa-dynamic
The package declares a dsh.bundle manifest, so its bundle patch inserts the provider row for you —
no hand-written patch entry is needed.
To select it, override the web row in $DSH_HOME/profiles/web/cordis.patch.yml:
- id: web
name: '@deepseek-ai/dsh-web'
config:
searchProvider: exa
fetchProvider: http
A patch replaces the targeted row's whole config rather than merging into it, so
fetchProvider: http must be restated or the fetch provider is dropped.
Then give it a key, either as plugin config:
- id: web-search-exa-dynamic
name: dsh-web-search-exa-dynamic
config:
apiKey: 'your-exa-api-key'
or through the environment. apiKey is declared role('secret'), so it never appears in a
describe() response — but a plain-text config file is still a plain-text config file; prefer the
environment when you can.
On $DSH_HOME/.env. The plugin reads apiKeyEnv (default EXA_API_KEY) through the harness's
launch-environment snapshot, which is documented to consult the inherited environment, the invoking
directory's .env and the Harness home's .env. That worked in some deployments and not in
others — on one Windows install the snapshot came back without the variable even though the file
was correct, and the config apiKey above was the fix. If your provider reports
registered but unavailable, the key is not reaching it; set apiKey directly.
Restart dsh web after changing the environment. cordis.patch.yml itself is hot-reloaded, so
config edits apply without a restart.
Configuration
Every field has a safe default; you normally only supply a key.
| Field | Default | Meaning |
|---|
providerId | exa | Registry id. Change it only to coexist with another Exa provider. |
apiKey | unset | Literal key; falls back to apiKeyEnv. |
apiKeyEnv | EXA_API_KEY | Environment variable consulted when apiKey is unset. |
baseURL | https://api.exa.ai | Exa endpoint; /search is appended. |
searchType | auto | Retrieval type — see below. Runtime-settable with /exa type. |
numResults | 8 | Source cap. Runtime-settable with /exa results. |
dynamicHighlights | true | On by default; adds the required Exa-Beta header. Runtime-settable with /exa. |
highlightsMaxCharacters | unset | Per-page highlight cap, used only when dynamicHighlights is false. |
dynamicHighlights is never combined with highlightsMaxCharacters: Exa sizes and distributes the
shared budget itself when dynamic is on, and its docs warn against combining the two.
The /exa command
Typed in the composer. It runs directly against the interface and creates no model message.
| Command | Effect |
|---|
/exa | Toggle Dynamic Highlights |
/exa on / /exa off | Set them explicitly |
/exa type | List the retrieval types |
/exa type deep | Set the retrieval type |
/exa results | Report the source cap |
/exa results 3 | Set the source cap |
/exa status | Report every knob, the available types, and the real ceiling |
Plain words, no punctuation: the command declares no argument hint, so the composer inserts no
template to edit around. /exa status lists the retrieval types too, so "which types were there
again" never costs a second command, and a mistyped argument replies with copy-pasteable examples.
Writes land in the web-search-exa-dynamic settings namespace's user layer, so they survive a
restart. Clearing that section returns the plugin to its configured defaults.
Measured on one provider instance, one query: switching Dynamic Highlights off took the same search
from 12,716 to 57,958 highlight characters — a 4.6x difference, applied on the next search.
Retrieval types
Exa's type is the latency/quality dial. All eight were verified against the live API; measured
latency for one query, 8 results:
| Type | Measured | Use |
|---|
keyword | 464 ms | Keyword only, fastest |
neural | 737 ms | Semantic retrieval |
fast | 798 ms | Speed with minimal quality loss |
instant | 856 ms | Real-time (chat, voice) |
auto | 1,914 ms | Default |
deep-lite | 3,116 ms | Lightweight synthesized output |
deep | 5,282 ms | Multi-step reasoning |
deep-reasoning | 18,278 ms | Hardest research tasks |
The first-party provider's schema lists only auto, keyword and neural — that set is stale.
This provider exposes all eight.
The deep* types are discounted by this seam
Measured through this provider's own class, same query, dynamic highlights on:
| Type | Time | Sources returned |
|---|
fast | 718 ms | 8 |
auto | 215 ms | 8 |
deep | 6,891 ms | 3 |
deep-reasoning | 14,776 ms | 4 |
The raw API returns 8 results for deep; the rest carry no non-blank highlight and are dropped,
because the seam has no other field to derive a snippet from and inventing one would make the seam
lie. The deep* family's real product is the synthesized output, which WebSearchSource has no
field for. In practice the useful range here is keyword, neural, fast, instant and auto.
Result count belongs to dsh-tool-web
Worth stating plainly, because it is easy to misread:
- The model-facing
web_search tool takes only queries — the model cannot ask for a count.
- The ceiling belongs to
dsh-tool-web: searchMaxResults, default 8. Its own comment:
"The consumer owns the returned-context limit; providers and models do not."
- The tool sends
maxResults on every call, and the seam truncates the returned sources to it —
so no provider can exceed that ceiling.
That makes this plugin's numResults one-directional: it can pull the count down, never up.
| Configured | Tool ceiling | Sent to Exa |
|---|
| 3 | 8 | 3 |
| 12 | 8 | 8 (clamped) |
| 20 | 8 | 8 (clamped) |
/exa status and /exa results report the ceiling the provider actually observed, so a clamped
value is explained rather than silently applied. To raise the ceiling itself, set searchMaxResults
on the tool-web row once:
- id: tool-web
name: '@deepseek-ai/dsh-tool-web'
config:
searchMaxResults: 20
Raise it once and everything above stays a runtime /exa results decision. Note this raises the cap
for whichever provider is active, so it also affects the DeepSeek provider if you switch back.
Known limitations
- Exa's beta surface can move.
dynamic-highlights-2026-08-28 is a research preview; a change on
Exa's side means updating DYNAMIC_BETA_VALUE.
- Results without highlights are dropped, matching the seam's rule. With dynamic highlights on,
8 of 8 results carried a highlight in testing, so it rarely fires.
- No
category, domain or date filters, and no full text. Those are Exa features this provider
does not expose yet.
- One of this and the first-party Exa provider per profile. Both register the provider id
exa
by default; running both needs a distinct providerId on one of them.
- Tested against dsh
0.1.5-rc.1 only, which is what the peer ranges pin.
- Without a settings service the
/exa writes are in-memory only. The provider itself works
either way; without a command registry there is simply no /exa.
Development
node test/index.test.js # 34 unit tests, no API key needed
EXA_API_KEY=... node test/live.mjs # hits the real API, spends credit
Run the test file directly rather than through node --test: the test runner spawns a child process
per file with piped stdio, which fails with spawn EPERM in a restricted sandbox.
Uninstall
dsh plugin --profile web remove dsh-web-search-exa-dynamic
Remove the web override from cordis.patch.yml to return to the built-in DeepSeek search. That
edit is hot-reloaded, so it takes effect immediately.
License
MIT
