Tweaking of README, intro, and tests.

doc/intro.md

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+# Introduction
+
+## Disclaimer
+
+This library is supplied in the hope that it may be useful, but results computed with it should not be taken as authoritative but should be checked against other sources. I do not have enough expertise to guarantee its results are correct.
+
+## General architecture
+
+### The packet
+
+The 'packet', in the terminology of this library, is a map which has bindings
+for some of the following keywords:
+
+1. `:absolute-humidity` *grammes per metre<sup>3</sup>.*
+2. `:actual-vapour-pressure` *Pascals*
+1. `:dew-point-celsius` 
+2. `:pressure-pascals` 
+3. `:pressure-millibars` 
+4. `:relative-humidity` *percentage, 0...100.*
+5. `:saturation-vapour-pressure` *Pascals*
+6. `:temperature` *assumed to be &deg; Celsius*
+7. `:temperature-celsius` 
+8. `:temperature-kelvin` 
+9. `:volume` *in metres<sup>3</sup>, relative to 1 at standard temperature and pressure.*
+10. `:wet-bulb-temperature-celsius` *in &deg; Celsius.*
+
+These keywords represent variables in the pressure equations, and they are all
+to a degree inter-related; so if you have (or can assume) some of them, you can
+compute others.
+
+Rather than having a tangle of functions all of which call one another, which seemed likely to result in horrible messes and potential infinite recursion, there is one central function, `humidity.core/resolution`, which takes a partial packet and repeatedly tries to compute the values for more variables until it can compute no more, and then returns the enhanced packet.
+
+Thus:
+
+```clojure
+humidity.core=> (use 'humidity.core :reload)
+nil
+humidity.core=> (resolution :relative-humidity 100 :temperature-celsius 35)
+{:relative-humidity 100, :temperature-celsius 35, :pressure-pascals 101325, :pressure-millibars 4053/4, :saturation-vapour-pressure 5622.488734516426, :temperature-kelvin 308.15, :absolute-humidity 3953.618101887827}
+```
+
+### Naming
+
+Associated with each variable there is a namespace of the same name which contains a function, whose name is the name of the variable with `-fn` appended, that takes a packet, and, provided that packet contains enough information to compute that variable, returns a numeric value, else `nil`.
+
+### Validation
+
+A packet may be validated by calling the function `validate`. This recalculates all values in the packet, and, by default, tolerates discrepancies of up to 1%. This tolerance can be varied by binding the dynamic variable `*validation-limit*`. Validation merely checks that the values within the packet are consistent with one another, and does not properly account for pressure, so will not be valid at altitude.
+
+```clojure
+humidity.core=> (validate {:absolute-humidity 3953.618101887827,
+           #_=>  :actual-vapour-pressure 4765.10094206357,
+           #_=>  :dew-point-celsius 35.00000000000001,
+           #_=>  :pressure-millibars 1013.25,
+           #_=>  :pressure-pascals 101325,
+           #_=>  :relative-humidity 100,
+           #_=>  :saturation-vapour-pressure 5622.488734516426,
+           #_=>  :temperature-celsius 35,
+           #_=>  :temperature-kelvin 308.15,
+           #_=>  :volume 1.1281347245103424,
+           #_=>  :wet-bulb-temperature-celsius 35.11625928298915}
+           #_=> )
+true
+
+humidity.core=> (validate {:absolute-humidity 3953.618101887827,
+           #_=>  :actual-vapour-pressure 4765.10094206357,
+           #_=>  :dew-point-celsius 35.00000000000001,
+           #_=>  :pressure-millibars 1013.25,
+           #_=>  :pressure-pascals 101325,
+           #_=>  :relative-humidity 95, ;; <-- intentionally wrong
+           #_=>  :saturation-vapour-pressure 5622.488734516426,
+           #_=>  :temperature-celsius 35,
+           #_=>  :temperature-kelvin 308.15,
+           #_=>  :volume 1.1281347245103424,
+           #_=>  :wet-bulb-temperature-celsius 35.11625928298915}
+           #_=> )
+ERROR: key: :dew-point-celsius; a: 35.00000000000001; b 34.07737599732603; errror: 2.857142925262451%.
+false
+
+humidity.core=> (binding [*validation-limit* 5]
+           #_=> (validate {:absolute-humidity 3953.618101887827,
+           #_=>  :actual-vapour-pressure 4765.10094206357,
+           #_=>  :dew-point-celsius 35.00000000000001,
+           #_=>  :pressure-millibars 1013.25,
+           #_=>  :pressure-pascals 101325,
+           #_=>  :relative-humidity 95, ;; <-- intentionally wrong
+           #_=>  :saturation-vapour-pressure 5622.488734516426,
+           #_=>  :temperature-celsius 35,
+           #_=>  :temperature-kelvin 308.15,
+           #_=>  :volume 1.1281347245103424,
+           #_=>  :wet-bulb-temperature-celsius 35.11625928298915}))
+true
+```
+
+## Developing
+
+This is a fairly standard [leiningen](https://leiningen.org/) project. I  anticipate that most Clojure developers will have leininen installed, even if they no longer use it much. Start a repl with
+
+```
+lein repl
+```
+
+and hook in your preferred editor as appropriate for that editor.
+
+Full documentation is available [here](https://www.journeyman.cc/humidity).
+
+## Testing
+
+Tests are reasonably complets but all could do with more examples, especially around the crucial 35&deg; C wet bulb area and towards the extremities of  normal weather range. If you are contributing additional code, I would appreciate it being accompanied by tests.
+
+I suggest running tests using
+
+```
+lein cloverage
+```
+
+As this gives not only pass/fail output, but also test coverage output.
+
+Current test results are [here](cloverage/index.html), for comparison.
+
+## Contributing
+
+Pull requests are welcomed, provided they do not contain AI generated code. I'm not going to waste time debugging Claude's mess, my own is bad enough.
+
+## License
+
+Copyright © 2026 Simon Brooke. Licensed under the GNU General Public License,
+version 2.0 or (at your option) any later version.